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3 Terminal Perovskite/Silicon Tandem Solar Cells

Infrastructure: EPFL CSEM_Evatec Clusterline

Status: Finished

Our research focuses on the integration of silicon bottom solar cells featuring interdigitated back contacts (Si IBC) and perovskite top cells into highly efficient 3-terminal tandem devices. This tandem device approach is very tolerant towards spectral variations, mitigates the impact of different degradation behaviors of the two sub-cells. Therefore, at ipv, we have fabricated and characterized first Si IBC bottom cells with different front and rear side morphology and have compared their performance. Then, we deposited wide band gap (~1.7 eV) perovskite top cells wet-chemically directly onto the front surface of the Si IBC bottom cells. Conformal wet-chemical deposition of the perovskite top cell on Si bottom cells with ~5micrometre wide-sized pyramids is challenging and displays the main bottleneck for our 3T perovskite/silicon tandem cell development. The uniform intermediate layers will allow fabrication of shunt-free tandem solar cells, thus help us to further optimize the 3T device.


High-purity nanoparticles for Perovskite Solar Cells Performance enhancement

Infrastructure: UNITOV_CHOSE-S2S

Status: Planning

Various nano-particle have been shown to potentially improve the performance of Perovskite solar cells. The Nanoparticles are generally produced trough wet-chemistry process, which inevitably comes with impurities such as surfactants, emulsifiers, catalysts, etc. and besides is generally complex to interface with microfabrication production equipment. In this project, the Gas aggregation process will allow the generation of high-purity NPs by a purely physical synthesis: In this process, a metallic vapor is generated by sputtering in a large aggregation volume at moderate vacuum. Fraunhofer FEP pioneered the use of Gas-Flow-Sputtering (GFS) source for this process, enabling the production of NPs from virtually any metal, including ferromagnetic metals in relatively large quantity and over large area. This process is readily applicable industrially (TRL-4).


With the great efforts of the photovoltaic community, hybrid organic-inorganic perovskite solar cells have reached unprecedented power conversion efficiencies (PCEs) as high as 25.7%. However, the biggest shortcoming is the instability of the devices. As a result, this study focuses on optimizing atomic layer deposition of SnOx/Al: ZnO and ZnO on top of PCBM in an inverted perovskite solar cell architecture. The p-i-n device design will be used, with a stack of Glass/ITO/PTAA/PFN-Br/Cs0.05FA0.81MA0.14PbI2.7Br0.3/PCBM/Buffer layer/ITO/Cu. We believe a comparison study of the buffer layers deemed necessary in identifying the ideal buffer layer for highly efficient and stable device. As a result of this optimization, the devices will function with improved stability. Furthermore, manufacturing on large modules demonstrates the feasibility of industrialization.


Numerical simulations via Silvaco TCAD simulator provides in-depth physics insights along with realistic observations of the design parameters that influence the PV performance of the solar cell. In this collaborative project, perovskite solar cell (PSC) will be simulated in tandem with Silicon for enhancing the PV performance. A comparative investigation for couple of electron transport layers (ETL) and hole transport layers (HTL) will be undertaken to analyze the band offsets at various interfaces as well as examine their electrical and optical properties. Various design parameters such as doping concentration, thickness of layers, defects states, and temperature variation analyses will be executed to optimize the device. For veracity of simulation studies, the PV data for a stable PSC (over one year with minimum degradation in power conversion efficiency) will be incorporated at AM 1.5 sunlight. Articles from the project will be published in reputed journals for widespread reach.


There is a huge gap between making small cells and modules. Conveniently, multiple stand alone perovskite cells (~0.1 cm square) can be made by spin coating techniques. Meanwhile, the policy makers and community at large want to see data obtained from modules at real outdoor conditions, leaving small cells tested under simulated and controlled ambient less relevant to paving way for perovskite PV to enter market. Our project aims to provide evidence of outdoor testing of solution-processed emerging PV suitable and potential for cloudy climate such as that of the UK. We clearly see VIPERLAB as an accelerator for us to establish the know-how and minimize resource waste in shifting from small cell to a minimodule 10 cm x 10 cm. By the end of our project (2024), we will also develop larger 30 cm x 30 cm modules. Instead of conducting a specific experiment, it would be a great gain for us to learn know-how and establish our baseline alike to other more experienced research groups.


Comparing ageing dynamics of n-i--p and p-i-n perovskite solar cells

Infrastructure: HZB_MPP-Ageing

Status: Ongoing

Operational conditions of perovskite solar cells include diurnal light/ dark cycling, which were shown to induce reversible changes in cell performance. We are currently investigating these reversible changes to elucidate the mechanistic origin of these reversible variations, their impact on the daily power output of the cells, and methods to affect/ reduce these performance variations. Towards that end, in this proposal we plan to compare the ageing dynamics of n-i-p and p-i-n cell architectures based on mixed cation halide perovskites.


HAXPES studies of functional perovskite interfaces

Infrastructure: HZB_XPS/HAXPES

Status: Finished

Understanding the energetics, structure and chemistry of HaP interfaces is key for developing HaP as a functional material for solar cell and light emitting diode applications. We have developed a methodology to carry out operando HAXPES measurements on working lead halide perovskite solar cells interfaces through a design of thin interface and contact layers. This would allow us to elucidate the band alignment, interface reactions and voltage losses/gains across the interfaces of perovskite solar cells with different selective contacts comparing dark and illuminated samples.


Temperature coefficients for maximum power, open-circuit voltage and short-circuit current are essential parameters for any commercially available PV module. Since the perovskite and perovskite tandem devices are used more and more outdoors, the knowledge of their temperature coefficients is deemed necessary. The main target of this proposal is to measure the temperature coefficients of several perovskite single and perovskite/Si tandem at different degradation stages. In order to achieve this, several perovskite mini-modules at different degradation stages will be tested at different temperature conditions.


Influence of the HTL in FASn-PSCs

Infrastructure: CENER_MODELAB

Status: Ongoing

'Perovskite solar cells (PSCs) have revolutionized the field of thin-film solar cells and have gained the interest of the scientific community due to their remarkable optoelectronic characteristics complemented by their structure-property tunability and facile deposition techniques. A critical issue that PSCs encounter is the presence of lead in the photoactive semiconductor a cumulative toxicant that affects multiple body systems. Sn-based perovskite benefit from high carrier mobility and lower optical bandgap, which is more suitable for photovoltaic applications. Currently the performance of Sn-based PSCs is 14.8% PCE. Here, through numerical simulation of different materials, prior to device fabrication, we want to (1) optimize the thickness of the materials (transport layers and perovskite) and (ii) determine the effect of carrier mobility and band offset of different hole transport layer (HTL) materials in the performance of FASnI3 PSC. The use of Silvaco TCAD simulation at VIPERLAB CENER-MODELAB will give us the possibility to explore different materials and understand how their optoelectromic characteristics affect the performance of the photovoltaic devices.'


Sample Processing and Characterisation

Infrastructure: IMEC_ThinFilm PV Lab

Status: Ongoing

Inverted perovskite solar cell mini modules are to be fabricated at IMEC which are to be partially characterized there, as well as using the outdoor and indoor testing facilities at the University of Cyprus (UCY). This will allow to test degradation pathways according to preliminary measurements which have been conducted as a joint effort between the two institutions within the past. It is theorised that the mechanisms depend on ion migration and the evolution of defects. This will need to be further tested by reproducing devices of the same architecture at IMEC, which will then be used for further measurements at the UCY.


CsPbI3-xBrx perovskite nanocrystals (NCs) are ideal emissive materials that can be tuned to emit pure-red colour (620-650 nm) used as the standard for ultrahigh definition displays. While these mixed-halide NCs can exhibit high photoluminescence quantum efficiency (approaching 90%), their photostability under ambient and elevated temperatures is inferior. In this study, we have demonstrated the beneficial impact of dimethylammonium (DMA) in extending the stability of these nanocrystals synthesized using the ligand-assisted re-precipitation (LARP) method in air. By conducting XPS measurements, we aim to obtain a chemical signature of possible DMA incorporation in the lattice of mixed-halide perovskite NCs, which will advance our understanding on the mechanism of improved stability in these systems. For eventual application in LEDs, we will also use UPS measurements for determining their work function and band edge energies for ensuring appropriate band alignment in the final device.


Perovskite solar cells are a new class of solar devices that have the potential to revolutionize the solar industry in the near future. However, one of the most limiting obstacles of this emerging technology is related to their stability: perovskites are prone to degradation under environmental conditions, i.e., oxygen and humidity, and operational conditions, i.e., light and bias. Each of these stimuli can lead to the loss of performance and the long-term stability of the device. Light may be able to introduce ionic defects, which are prone to migrate in the perovskite devices. On the other hand, photo-induced performance-loss can be entirely or partly recovered in the dark. In this proposal, we will aim to investigate changes in the dynamic response of devices due to light-induced defect formation as well as the impact of dark recovery cycles on the operational stability of solar cell devices.


CsPbIxBr3-x nanocrystals show ideal bandgaps for application in light emitting diodes and displays with emission wavelengths lying within the Rec 2020 colour gamut. Furthermore, in contrast to the pure-iodide compositions that require high temperatures to form the perovskite phase, mixed-halides afford facile synthesis through ligand assisted reprecipitation (LARP) in ambient conditions. However, these materials are still plagued by phase separation under optical/electrical excitations of intensities typical in a working device. Here, we try to alloy the A-site with dimethylammonium (DMA) to improve the phase stability while retaining high photoluminescence quantum yields. Our preliminary work indicates definite enhancement in stability and by using HR-TEM, (S)TEM-EDX and SAED facilities at VIPERLAB, we aim to further image the resultant nanocrystals, understand their size and shape dependence as well as probe their crystal structures as a function of the extent of A-site alloying.


Despite rapid progress in green and red perovskite light emitting diodes (LEDs), corresponding advancements in blue perovskite LEDs have been challenging. In this study, we have explored different compositional and ligand-capping approaches for demonstrating high photoluminescence quantum efficiency (PLQE) and improved charge transport in allinorganic blue emitting perovskite nanocrystals (NCs) synthesized by an ultrasonication process. Using (S)TEM imaging and EDX analysis, we aim to gather information about the size distribution and elemental composition of our NCs. Furthermore, HR(S)TEM imaging and SAED measurements will be essential to obtain the interplanar distances and structural information of our synthesized perovskite compositions. Results obtained from such investigations will help to substantially advance our understanding of blue emitting perovskite NCs, with exciting implications for electroluminescent LEDs.


Large area device fabrication and quantification of degradation mechanisms

Infrastructure: UNITOV_CHOSE-S2S

Status: Finished

The increasing energy demand in the last decades pushed the research community to find alternatives to conventional energy sources, and perovskite solar cells (PSC) have emerged as a potential choice of materials owing to their high power conversion efficiency (PCE). The device performance is now at par with mature technology at the lab scale, however, it lacks long-term stability, reproducibility, and scalability for mini-modules and modules. In the quest for stable and efficient halide perovskite, current efforts have been widely attracted by the use of formamidinium lead triiodide due to its lower optical band gap (1.47 eV) and through additivization stability, issues can be overcome. We aim to fabricate mini-modules (15x15cm2), with our developed materials and study their failure and degradation mechanisms


The interfaces of a perovskite solar cell (PSC) are crucial not only for the performance but also the stability of the device. It has been found that halo-functional hole transport materials (HTMs) can anchor to the perovskite surface creating an ordered and uniform layer, improving their resilience to degradation, as well as suppressing ion migration and recombination. This study aims to combine halogen bonding with substituents specifically designed to interact with the device electrodes, in order to further promote device stability and to extend the benefits to both conventional and inverted device structures. To this end, the two HTM variants will be synthesized with thiol and carboxylic acid groups, respectively. The fabricated PSCs are expected to become another step towards very stable and cost-effective perovskite solar cells.


Stability testing of perovskite mini-modules

Infrastructure: HZB_MPP-Ageing

Status: Ongoing

Stability testing of several perovskite mini-modules is expected to be implemented under the high-throughput aging system located at Helmholtz-Zentrum Berlin. The modules will be exposed under different irradiance and temperature levels in a cycled light-dark analysis. This procedure will mimic the outdoor testing and will demonstrate the performance trends at the different conditions. The measurements will extract also the diurnal efficiency degradation and performance recovery values. All the aging results will be compared to those collected outdoors at University of Cyprus (UCY).


Perovskite solar cells can be easily integrated into a multi-junction (tandem) architecture, thus can easily overcome the limitations of their single-junction counterparts. For this, they can be combined with silicon, CIGS or organic solar cells or with different perovskites. In all perovskite tandem solar cells (TSCs), top (narrow bandgap, NBG) and bottom (wide bandgap, WBG) subcells must be separately optimized to enhance open circuit voltage and fill factor. In this project, we use a comprehensive defect passivation approach to reduce recombination in both subcells and at their interconnection. Due to the limitations in measuring electro-optical properties of our NBG cells at our group, we seek a collaboration with another group which has capabilities to measure quantum efficiency and photoluminescence beyond 950 nm.


Flexible Perovskite solar cells (PSCs) have emerged as a promising technology for solar energy conversion due to their high efficiency, low-cost, lightweight, and thin characteristics. However, their scalability is a major challenge that needs to be addressed for commercialization. As the preliminary work, using of a non-toxic solvent system and low deposition temperature for the flexible all-blade coated PSCs with 14%. PCE was done. Additionally, flexible semitransparent devices using FAPbBr3 perovskite as part of the European Project CitySolar were manufactured that showed up to 60% average visible transparency and delivered 5% PCE. We propose the development of roll-to-roll (R2R) deposited perovskite solar modules using a cost-effective and robust scalable slot-die coating technique. This work can produce a highly efficient and stable semitransparent solar modules suitable for BIPV applications, opening new opportunities in the PV market.



Infrastructure: HZB_MPP-Ageing

Status: Ongoing

Processing high-quality, flexible perovskite hybrid films require obtaining defect-free, well-coupled electrical interfaces with adjacent and equally selective contact layers. This work aims to demonstrate that flexible devices fabricated by the Slot-die Coating method in different architectures can eliminate different microscopic defects that could improve photovoltaic parameters and stability in flexible devices.


We will use hard X-ray photoelectron spectroscopy (HAXPES) measurements to investigate the chemistry and defect formation at the interface between metal halide perovskite thin films and oxide layers grown by atomic layer deposition. We will track reactions at the buried interface and introduce interlayers that protect against the impact of the deposition process.


Improving the longevity of perovskite solar cells

Infrastructure: IMEC_TFPV lab

Status: Ongoing

By this proposal, I am asking for access to the Maximum power point tracking (MPPT) machine and laminators available in imec institution. I would need to laminate my devices and then age them under MPPT condition.


Our project aims at performing characterization experiments that would allow for a better understanding of the degradation pathways of perovskite solar cells and modules. The intention is to prepare samples of inverted perovskite solar cell with the ITO/NiO/perovskite/C60/BCP/Cu architecture, and minimodules following the same layer stack. These devices will be prepared at the TFPV infrastructure at imec. The final devices will be characterized by means of impedance spectroscopy measurements and outdoor degradation protocols.


Flexible biosusbtrates for perovskite solar cells

Infrastructure: CEA_WV P

Status: Planning

Bio-substrates have been getting attention in the recent years, due to their attractive optical and gas barrier properties. Nanocellulose has the interesting of light scattering. This would elongate the pathlengths of incoming light in solar cells, giving the light a bigger opportunity to hit the active area. Also due to their flexibility they could be used in high production techniques such as roll-to-roll manufacturing. Moreover, they are easy to dispose at the end of the device lifetime making recyclability more attractive to venture capital. We would like to use our bio-substrates to fabricate flexible perovskite solar cells using the VIPERLAB facilities and characterize their electrical and gas barrier properties. NOTE: The system does not let me add more than one instrument in technical requirements, but we need CEA_WV_P, CEA_He_P and CEA_El_Ch


Recent promising results and the prospect for obtaining temperature-stable devices by removing organic cations are generating high expectations in CsPbI3-based perovskite solar cells (PSCs). However, the JV hysteresis is large and the power conversion efficiencies (PCEs) are still lower compared to devices based on hybrid organic-inorganic perovskites. Various improvements have been achieved in PSCs by incorporating interlayers between the perovskite and the ETL. Herein, we propose a new approach consisting of the introduction of a thin (1-2 nm) 0.5% Nb:TiO2 film between the CsPbI3 perovskite and the pristine TiO2 (hetero-ETM). This approach integrates both the passivation effect observed in our previous study and an interfacial dipole between ETL/perovskite, increasing the driving force for the extraction of electrons. The aim of this study is to compare the device stability of hetero-ETM based all inorganic PSCs respect to bulk 0.5%Nb doped TiO2 based PSCs.


Encapsulation of Perovskite Solar Cells and Stability Testing

Infrastructure: HZB_MPP-Ageing

Status: Finished

Despite the high power conversion efficiencies above 25% achieved with lead-halide perovskites, significant commercial success is yet to be witnessed with perovskite solar cells (PSCs) due to insufficient stability of these devices. Device encapsulation, essential for commercialization, is still a challenge and the range of possible techniques is limited by several factors including high chemical sensitivity of PSC materials and low tolerance to elevated temperatures during the encapsulation. This research stay at HZB will focus on encapsulation with n-i-p structure. During this visit, PSCs fabricated at ICN2 will be encapsulated using 3 encapsulation strategies both at home and host laboratories. These experiments will be important to validate previous results obtained at ICN2 regarding the performance of different methods of encapsulation. Once the quality of encapsulation is confirmed in climate chambers, the devices will be used for outdoor experiments in Berlin and Barcelona.


Numerical simulation of a free-HTL perovskite FASnI3-based solar devices

Infrastructure: CENER_MODELAB

Status: Finished

In the work, novel free-HTLs will be designed using the simulator to explore their potential and performance for HTL-free PSCs. In order to obtain optimal device performance, several device parameters, including the thickness, doping concentration, and defect density for the absorber and also other layers will be investigated.


Potential-induced degradation (PID) can severely limit the lifetime of solar cells. In the case of silicon cells, it was possible to understand the causes of PID and to avoid it by technological changes. However, it is very likely that perovskite solar cells (PSCs) will also be affected by the phenomenon. Even though the stability of PSCs under elevated temperature and irradiation has been investigated by several studies, there is only limited data on PID. To the author's best knowledge, only three papers have been published, and they all indicated the degradation of PSCs under high voltage stress [1]- [3]. With the limited knowledge and the lack of PID test standardization, efficient measures against PID in PSCs remain unknown. In this study, the possibilities of accelerated PID tests of PSCs and the PID sensitivity of different PSCs with varying encapsulants will be investigated through a postmortem root cause analysis.


Here, i propose to study the Hybrid-organic-inorganic Zn doped FASnI3 and FAGeI3 perovskite for photovoltaic application. In fact, I will investigate and discuss the structural, electronic (band structure, band gap energy value), and optical properties of this solar perovskites photovoltaic material using the DFT method implemented in the Quantum Espresso package.


Perovskite solar cells are one of the most promising photovoltaic technologies, with an astonishing development within a very short time. The next step towards commercialization is to make this technology compatible with largescale production. One attractive method is the roll-to-roll (R2R) slot-die coating process, in which the active layers are continuously deposited on a large area flexible substrate, ideally under ambient atmosphere. However, the typical solvents used for the perovskite solution are toxic (e.g. DMF, NMP), which raises serious environmental and health concerns. At SAULE we are currently testing greener alternatives and our current best recipe for blade-coating deposition under ambient atmosphere is based on ACN, 2-ME and DMSO with ionic liquid additive, but ultimately it is intended to use only green solvents. The aim of this study is to transfer the already optimized perovskite blade-coating process to a R2R slot-die process, without losing perovskite quality.


We prepare sequentially evaporated (Cs,FA)Pb(I,Br)3 perovskite layers on an ITO/PTAA substrate. These samples are post-annealed at 100C to complete the interdiffusion and layer reaction. We aim to investigate the effect of different sequencing of the components FAI, CsI, PbI2 and PbBr2 on the interface reactions during processing and find advantageous interface species for cell preparation. These effects are scarcely studied. Our sequentially deposited perovskite layers will be processed to complete solar cells in a p-i-n structure in a VIPERLAB facility, where standard cell characterization will also be performed. The transport from our lab to the VIPERLAB facilities will be ensured in a nitrogen atmosphere. Wet-chemical reference cells will also be prepared.


Solar energy is one of the promising technologies for clean energy production. In the last decade, the photovoltaic industry has witnessed a skyrocketing growth in the power conversion efficiency of organic-inorganic perovskite solar cells (PSCs) from primal 3.8% to a confirmed 25.7%. Spiro-OMeTAD is the most commonly developed Hole-transporting material (HTM) with an expensive complicate synthesis. Besides, it needs hygroscopic doping that reduces the stability of device. To meet the necessities for future commercialization, eco-friendly low-cost HTMs have been widely investigated and studied. P-type Cu-based chalcogenide semiconductors are promising substitute because of high mobility and low cost synthesis processes. However, their efficiency is lower than the value obtained from the expensive competitor, Spiro-OMeTAD. It has been well evidenced that apart from the importance of composition and microstructure of heart of device, perovskite active layer, interfacial optimization of c


Sunplugged develops flexible CIGS-PV modules for integrated photovoltaics. Sunpluggeds made-to-measure photovoltaic foil is based on three proprietary technologies combined in one unique approach: (1) a band-gap tunable solar cell process, (2) a digitally controllable serial interconnection that allows customer oriented production 'on-the-fly' and (3) a flexible substrate that facilitates ultra-thin, lightweight and stable packaging. In order to achieve significantly higher efficiencies tandem devices are a very promising concept. The main objective of the project is to investigate the feasibility and viability of a high efficient, 2-terminal (2T) thin-film multi-junction perovskite/CIGS solar cell which builds upon the established technologies. The flexible thin-film perovskite/CIGS tandem devices will bring a substantial performance boost to Sunpluggeds offerings whilst the unique features like made-to-measure production and lightness can be maintained.


The maximum conversion efficiency a single junction solar cell can achieve is determined by its band gap, and is hence inherently limited by photon thermalization and transmission. Multiple-junction solar cells provide an opportunity to surpass the efficiency given by the Shockley-Queisser limit via a more optimized usage of the solar spectrum. A tandem structure consisting of the perovskite/CIGS combination is very promising for several reasons: i) both materials have high absorption coefficients and long diffusion lengths, ii) both absorbers have tunable band gaps which cover the ideal values of 1.7-1.9 eV for the top cell and 0.9-1.2eV for the bottom one iii) both devices have separately achieved high conversion efficiencies, and iv) both solar cells are thin-film structures allowing a possibility for flexible applications. An optimization of the tandem structure requires detailed measurements and an accurate interpretation of the data.


Solution-processed perovskites enabled high efficiency photovoltaic cells. In these devices, organic semiconductors (OSCs, e.g., spiroOMeTAD, PTAA) are used as charge transport layers. To this end, stable and efficient molecular dopants have been developed to improve the efficiency as well the environmental stability of perovskites solar cells. In this project, we seek to develop Lewis acid doped hole transporting layers by using a suite of wet-lab facilities and characterization techniques at IMEC(Belgium) to gain insights into the morphology-stability-property relationships. In addition, we will correlate these findings with the structural analysis obtained from solid-state NMR and EPR spectroscopy (experiments will be carried out at Lille University, France), and hence provide insights into doping mechanisms and efficiencies of contact layers in perovskites solar cells.


The objective of our research is to develop a novel perovskite solar cell, composed of a low-dimensional lead-free perovskite material with a superlattice of two organic-inorganic crystal structures. For this, we will study profoundly their electronic, optical and quantum transport properties2. DFT calculations via the wien2k package and Quantum Espresso - will be used to evaluate the properties of the 2D, and 3D perovskite structures and subsequently the superlattices composed of inorganic and organic perovskites in this study. The band gap of the superlattice is refined by increasing the thickness of the perovskite layer. As an expected result, the valence band maximum and conduction band minimum states of the superlattice are separated on different atomic levels, minimizing electron and hole recombination, which is advantageous for carrier separation and charge collection.


Optoelectronic characterization of perovskite mini-modules

Infrastructure: AIT_Testing

Status: Finished

The proposed work aims to explore a novel approach for the measurements of the spectral response of mini-modules. The novel approach will utilize strip illumination so as to avoid the necessity of illuminating the whole device. In addition to this, measurement of the performance of several perovskite mini-modules will be conducted as part of an inter-comparison campaign between the host organization (AIT) and the University of Cyprus (UCY). Spatially-resolved techniques (Electroluminescence, Photoluminescence and Lock-In Thermography will be utilized for the characterization of the modules as well.


Perovskite nanocrystals have shown great promise as light harvesting material for solar cells. Preliminary studies show that charge transfer occurs in at different time scales in CsPbBr3, from nanoseconds to a few femtoseconds. The charge transfer is also different between nanocrystals and bulk material and is shortened when in contact with a transition metal dichalcogenide. We propose to use core-hole clock spectroscopy to study the ultra-fast charge in bulk and nanocrystals of CsPbBr3 and try to quicken the charge transfer in the nanocrystals by introducing a transition metal dichalcogenide.


The most important R&D challenge of photovoltaic domain is today the elaboration of the next generation of highly efficient solar cells based on perovskite/silicon tandem architecture. In the literature, most of these perovskite/silicon tandem solar cells are elaborated on CMP (chemically and mechanically polished surface) silicon wafers. This configuration is actually not compatible with an industrial development. Very recently CSEM/EPFL demonstrate the elaboration of perovskite/silicon tandem solar cells on standard texturized surface reaching high efficiency up to 31.25 % in combinaison with the use of a specific conformal process for the deposition of the perovskite layer. The goal of the scientific case proposed here is the elaboration of perovskite/silicon heterojunction tandem solar cells with an optimised and industrially compatible surface texturation.


Advanced imaging for perovskite solar cells

Infrastructure: Fraunhofer_charPSC

Status: Finished

Combining the expertise between two photovoltaic characterisation teams at the Australian National University (ANU) and Fraunhofer-ISE, we aim to develop a series of imaging methods to spatially resolve critical optical and electrical parameters of perovskite solar cells and materials. Particularly, the project will focus on light-based imaging techniques for implied open circuit voltage iVoc and its temperature coefficient, ideality factor nid, activation energy Ea of recombination, sub-bandgap absorptivity, minority carrier lifetimes, and posiibly series and shunt resistances for various perovskite structures. It may also adopt some of these mentioned techniques to characterise subcells in silicon-perovskite tandem solar cells.


Recent experimental results demonstrates the potential of thin film chalcogenides as selective contacts for high efficiency solar cells. One of the main advantages of this family of materials is the ability to easily tune the bandgap as well as the bands position, to be a highly selective contact for holes or electrons. In this work we propose to investigate a new clase of low-dimensional chalcogenides (Sb2(S,Se)(3) and chalcohalides (SbSe(Br,I)) deposited by co-evaporation techniques as selective contacts in perovskite technologies. These materials have shown a high flexibility in terms of bands design, as well as control of the conductivity from n to p-type. These selectives contacts will be prepared by co-evaporation at UPC, and then tested at UNITOV partner of VIPERLAB innitiative, to demonstrate the first selective contacts based on low dimensional chalcogenide and chalco-halide compounds for perovskite. Solar cell devices will be fabricated and fully characterized.


Slot-die coating of PTAA and Perovskite film on plastic foils

Infrastructure: UNITOV_CHOSE-S2S

Status: Finished

Perovskite solar cells (PSCs) have already shown their potential to commercialize in the near future. However, more research focus on scalability and stability is required to accelerate a faster entry. Recently, the blade coating technique shows promising results in small area module fabrication in the laboratory. However, one main disadvantage is its incompatibility to scale with high throughput and yield. Therefore, this research focuses on optimizing PTAA (hole transport layer) and perovskite film by slot-die coating technique. We will utilize the p-i-n device configuration with a stack consisting PET/ITO/PTAA/Cs0.17FA0.83Pb(I0.9Br0.1)3/C60/BCP/Cu. Thereby the devices will perform with better stability and negligible hysteresis without using dopants for transport layers. Furthermore, fabricating on a flexible substrate provides an advantage in utilizing the roll-to-roll industry scale technique.


Synthesis of a Hole Transporting Material for perovskite solar cells


Status: Finished

Impressive improvements were done on Perovskite Solar Cells (PSCs) the last few years, achieving 25.7%, making them very competitive compared to other inorganic technologies. However, the stability of PSCs still needs to be addressed for industrial production Development of interfacial layers (for Electron Transport and Hole Transport) is a key parameter. Salts used as dopants for Hole Transporting Materials (HTMs) are highly hygroscopic, favouring the degradation of the Perovskite layer. To overcome this issue new 'low dopant' or 'dopant-free' conductive HTMs, with passivation properties towards the active layer to reduce the degradation induced by light and extrinsic factors can be proposed. Carbazole/phenothiazine based small molecules demonstrated favourable structural and energetical features for application in PSCs. Access the VIPERLAB infrastructure will be an opportunity to take benefit of synthetic skills on these scaffolds to prepare and characterize a new molecule HTM.


Investigation of Hysteresis in all-inorganic perovskite solar cell

Infrastructure: CENER_MODELAB

Status: Finished

The efficiency of perovskite based solar cells have increased exponentially till 25.8% over a span of 12 years, which is the highest recorded efficiency evolution for any group of materials. Despite the stellar optoelectronic properties of the group of materials, there are stability issues that hampers the realisation of perovskite solar cells for long-term usage. Though lead-based perovskites have been proven to withstand ambient situations compared to other perovskites, the lead part gives rise to toxicity problem. In order to combat these problems, cesium based lead-free inorganic perovskites have been explored as solutions. The current proposal is intended to simulate lead-free CsGeI3 based all inorganic perovskite solar cells. Further, the work also intends to identify inorganic ETLs and HTLs so as to alleviate all elements inducing stability problems in the device configurations for ambient functioning.


Perovskite solar cells (PSCs) have the potential to become key players in the solar energy market, due to their high efficiencies, short energy payback time and versatility of applications. Highly efficient opaque PSCs employ metals as top electrodes, which increase the overall cost of the device, are not suitable for large scale manufacturing and have a detrimental effect on the cell stability. Developing low cost, metal-free, stable electrodes is therefore crucial to enable the commercialization of PSCs. In this proposal, Dyenamo will provide a commercially available low temperature printable carbon-based paste. This material will be tested at TNO as electrode for perovskite solar cells fabricated by large area compatible methods, such as slot die coating. Deposition of the electrode will be carried out by screen printing on 6 inch samples. Uniformity of the layer will be assessed and the performance of the cells evaluated under standard testing conditions.


Photostability of laser annealed MAPbI3 under different spectral regions.

Infrastructure: CENER_SOLPVLAB

Status: Finished

Organic Inorganic Halide Perovskites (OIHPs) solar cells have shown power conversion efficiencies (PCE) up to 25.6% on a lab scale. However, one of the challenges in large-scale manufacturing of solution-based perovskite solar cells (PSCs) is to prolong uniform heat treatment of the wet perovskite film over a large surface. One possibility is laser annealing as an alternative to conventional thermal treatment. Along with upscaling, Light Induced Degradation (LID) of PSCs under the operating conditions is one of the major bottlenecks towards commercialization. However, a detailed overview is lacking on the effect of various spectral regions of sunlight on PSCs fabricated outside the N2 filled glove boxes. In this work, we would study the stability of our laser annealed PSCs as compared to thermally annealed PSCs.


Here,i propose to study the Hybrid-organic-inorganic new silicon-based perovskite for photovoltaic application. In fact, i will investigate and discuss the structural,electronic (band structure,band gap energy value) and optical properties of the solar perovskites photovoltaic material FASiX3 (X=I or Br ) using the DFT method implemented in the Quantum Espresso package.


Fullerenes have sparked a lot of attention in recent years as a way to improve the existing high-performing p-i-n perovskite solar cells. Most the pristine fullerenes, display issues with layer morphology, device stability, and performance. Therefore, the introduction of dopants in fullerenes has been demonstrated multiple times to be beneficial by reduced transport losses, and decrease the charge-injection barrier at electrodes, resulting from the position shift of Fermi level relative to the carrier level. In this work, new cross-linkable silanes based on halide alkylammonium salts (HAS) are investigated in terms of the chemical structures by various spectroscopy techniques and via computational simulations. Furthermore, flexible perovskite solar cells were fabricated by incorporating three different silanes into the fullerene derivative, with efficiencies surpassing 19% on 1cm2 active area.


Goal of the proposed experimental work is the verification and calibration of a selfmade (UNISA) setup, developed for the measurement of the point-wise quantum yield spectrum in-situ during the exposure of Perovskite based Tandem solar cells to energetic particles and radiation. Some Perovskite based TANDEM solar cells, have been shown to be extremely stable under Proton irradiation and are hence good candidates for future thin-film space photovoltaics. The setup, based on LED excitation at different wavelengths and conversion of the generated photocurrent in a proportional frequency has been already successfully tested for the in-situ degradation monitoring of crystalline silicon solar cells under high energy proton irradiation under vacuum. In the moment we work on the modification of the setup for the characterization of TANDEM solar cells. It would be necessary however to calibrate the system and the FHI-ISE solar cell characterization facilities would be the ideal place for this.


Manipulation of the defective grain boundaries and pinholes in perovskite films is crucial to maximizing optoelectronic properties and stability of the perovskite solar cells (PSCs). It has been found that by introducing polymers to perovskite films, one may improve the crystallinity and morphology of the films. The various functional groups make it possible for the polymers to control over the morphology, passivate the trap states at grain boundaries, and improve carrier mobility. The aim of the study is to design such polymers in order to favour crystallization and reduce the trap states. By using controlled radical polymerization, copolymers will be synthesized which are capable of building hydrogen bonds with perovskite. The resulted PSCs are expected to be a part of the solution for obtaining highly stable and efficient solar cells.


Wide band gap perovskite solar cell

Infrastructure: IMEC_TFPV lab

Status: Finished

The aim of this proposal is to develop wide band gap perovskite solar cell, to be integrated later in the top of silicon heterojunction solar cell. First, we will focus on reproducing good quality FAPb(Ix,Br 1-x)3 perovskite absorber in the IMEC process. Then, the best wide band gap FAPb(Ix,Br 1-x)3 perovskite absorber will be incorporated in the IMEC stack as a reference p-i-n perovskite solar cell with Cu electrode. The resulted perovskite solar cells will be characterized by IV-measurements and MPP tracking. Based on the previous result we can optimize further the efficiency of the perovskite solar cell by adapting the p and n interfaces to have better energy level alignment, by adding other thin films. Afterwards, the best resulted solar cell with the best p- and -n-side interface materials will be used in the same stack with ITO top-electrode done by soft sputtering. Finally, we will perform IV-measurements with Si-bottom cell to determine how such tandem stack performs.


Perovskite solar cells (PSCs) have recently exceeded 25% conversion efficiencies approaching the single-cell efficiency limit. However, there is still room for improvements. Specifically, the stability and performance of perovskite solar cells can be related to the chemistry of the interfaces between the perovskite absorber and the charge transport layers (CTLs). In this view, replacing the currently used organic CTLs, which introduce optical parasitic absorption, shunting pathways and have poor mechanical properties, for inorganic based CTL could further improve the performance of PSCs. However, when a thin film deposition technique such as atomic layer deposition (ALD) is used to grow the electron transport layer directly on the absorber, it induces chemical modifications which lead to poor performing devices. In this study, we are going to evaluate the electronic and chemical profile of the interface between the ALD-grown SnO2 and a Cs0.15FA0.85Pb(I0.92Br0.08)3 perovskite absorber.


In this proposal I would use the VIPERLAB infrastructure CHOSE-S2S for study the stabilization effect of two-dimensional MXenes based on Ti, V, Nb and Mo for large area perovskite solar cells and modules. I propose to consider the impact of MXenes as dopant for the perovskite absorber as well as interlayer. Stabilization will be assessed by using light soaking.


Perovskite semiconductors have been reported to demonstrate high resilience to high energy radiation which has lead to a studies on their suitability in multijunction solar cells for space applications. This is in particular motivated by additional benefits such as a potentially lower cost for deposition of the perovskites and higher specific power. However, photovoltaics in space also undergoes thermal cycling where the temperatures vary between 373 K and 173 K. Therefore, any significant mismatch in thermal expansion in the layers within the device can result in catastrophic mechanical failure of the photovoltaic modules. Through this application, access to the EPFL/CSEM - PV LAB/PV CENTER (LARGE AREA) PSK/SI TANDEM PROCESSING infrastructure is requested for fabrication of perovskite/silicon tandem cells and reference single junction perovskite solar cells. These will be evaluated for their optoelectronic and mechanical characteristics under thermal cycling at Surrey.


Since CHOSE@UNITO ('UNITOV, CHOSE-MATERIALS') is experienced with reactions on the phenothiazine scaffold, 3,3'-(9-hexyl-9H-carbazole-3,6-diyl)bis(10-hexyl-10H-phenothiazine) will be synthesized starting from the already prepared 3,6-dibromo-9-hexyl-9H-carbazole. The molecule will be structurally characterized (NMR, GC, MS analyses) and its optoelectronic properties will be investigated (UV, fluorescence analysis) as well as its electrochemical properties (CV). Moreover, the resistance to moisture is going to be probed by contact angle measurements. These analyses will enable to understand if the synthesized small molecule can be used as dopant-free Hole Transporting Material in Perovskite Solar Cells.


Automated formulation and analysis of perovskite composition

Infrastructure: Juelich_AMANDA

Status: Finished

Atinary Technologies aims to deploy its Self-driving Lab platform -SDLabs- to accelerate the formulation, analysis and stability testing of perovskite composition. Atinary will provide the software backbone to integrate various robotics, database, data analytics and proprietary ML algorithms into a closed-loop experimentation system. The overall experiment follows a three-step process -Design, Make and Test- orchestrated and driven by Atinarys SDLabs in the cloud. This allows remote control of the experiments, from anywhere on any devices.


We have developed a fabrication route for perovskite films that allow substantial changes in the band gap of the semiconductor, by simply changing the iodide/bromide ratio in the precursor solution. A detailed analysis of various compositions of the photo absorber can provide further insights of efficiency limiting phenomena. Additionally, investigation of alternative hole transporting layers can reveal information about perovskite crystal growth and trap state formation. An automated process reduces the fabrication time for a large number of samples, which are essential for detailed analysis of phenomena like mentioned before.


To tackle extrinsic instability issues of Perovskite solar cells (PSCs), teams in HZB and CEA both developed a glass-glass encapsulation based on a butyl edge sealant and a polymer encapsulant. Both encapsulation strategies processed by vacuum lamination enable their PSCs to pass the IEC 61215 damp heat test. The aim of this collaboration between CEA and HZB is to evaluate the encapsulation materials used in both institutes through specific methods developed at CEA and characterization tools available there. Additionally, the effect of the process temperature on the barrier properties of the polymer encapsulants would be studied. The results of the experiments would enable us to optimize our encapsulation strategy and potentially lower the process temperature, thus widening the range of devices that can be laminated. Finally, this project would allow both teams in HZB and CEA to exchange knowledge and experience on the topic of encapsulation and stability of perovskite solar cells.


We are developing and studying the effect of spectral converting materials in perovskite solar cells to expand the utilization of solar spectrum. This will be conducted by Down conversion (DC) of UV-blue energy to the sub-bandgap energy of perovskite. The incorporation of these materials also affects device stability and therefore the critical lifetime assessment under defined protocol, i.e. applied stress tests of 1000 hours continuous illumination at one sun (light soak test) and 1000 hours exposure to a high humidity (relative humidity of 85 %) combined with exposure to a temperature of 85 oC (damp-heat test) is necessary to understand their role in improving lifetime of the modified devices. These stability tests in corroboration with other optoelectronic studies will help to understand and improve the efficacy of the DC materials.


Assessment of polyolefin based encapsulants for perovskite PV

Infrastructure: TNO_S2S P2L

Status: Finished

It is well known that external factors like oxygen and moisture can significantly reduce the stability of perovskite solar cells and modules. Moreover, the additives used in the encapsulant might lead to perovskite degradation. For this reason, it is critical to provide a proper encapsulation that will protect the cells from the environment and do not compromise their performance and stability. The results of the experiment will answer questions if the specific thermoplastic polyolefin encapsulants used for c-Si modules are also suitable for encapsulation of perovskite-based modules. If not, the experiment may provide first indications of what needs to be modified. The obtained knowledge will help in the development of stable perovskite modules for research purposes and towards the commercialization of perovskite-based PV products.


The commercialization of perovskite solar cells (PSCs) faces challenges in maintaining performance and reproducibility while upscaling. Meniscus coating is a high-throughput manufacturing process used in various industries, including solar cell production. However, achieving reproducible results for SnO2 deposition through blade coating is a significant challenge. The objective of this project is to fabricate a solar cell utilizing the ALD technique for the SnO2 layer and comparing its performance and reproducibility with the blade coating method. ALD is a highly scalable technique that can be easily integrated into existing production processes, making it a cost-effective candidate for large-scale manufacturing of PSCs. Its successful implementation could lead to commercially available PSCs in the future.


CsFA is an attractive PSK for high performance and stability PSK builds, as this PSK is bandgap-tunable and stable under environmental stresses. To reduce the fabricating cost for commercializing perovskite solar cells (PSCs), ambient fabrication process needs to be developed to induce formation of high-quality PSK films under exposure of moisture. However, CsFA is still not popular to be fabricated in ambient-atmosphere. Enabling formation of the CsFA-PSKs in ambient, the composition needs to be carefully selected, which is suitable for fabrication environment and deposition process. Nevertheless, the effect of CsFA composition on PSK formation in ambient-air has not been systematically studied to determine proper CsFA composition for further fabricating high performance and stable PSC in ambient-air.


Perovskite solar cell is a new emerging technology deeply studied in last decade. The interest in such technology is represented by the rapid growth in its efficiency. However, several open issues are still open such the degradation and the hysteresis behavior. In order to study and fully understand the physic behind such solar cells, the experimental characterization is not enough. An accurate numerical analysis should be performed. Describing a proper TCAD model is not straightforward and may require strong effort. The aim of this proposal is to describe a PSC in two different TCAD environments (Sentaurus and Silvaco) and compare the numerical results acquired from both TCADs in order to evaluate some possible differences.


Cu2ZnSnS4 nanoparticles as HTM for Perovskite Solar Cells

Infrastructure: SU_PV Manu & Test

Status: Ongoing

To increase the performance stability of perovskite solar cells (PSCs) the commonly used organic hole transporting materials (HTMs) can be substituted by inorganic ones. For this purpose, we employ Cu2ZnSnS4 nanoparticles (CZTS NPs) as HTM. The nanoparticle structure allows easy ink-based solution deposition methods. In preliminary work, we have obtained a PSC with CZTS as HTM more stable than the reference PSC with the organic HTM. In addition, after 50 days the efficiency of the device with the inorganic HTM is even increased by 80%, while the efficiency of that with organic HTM decreased by 22%. Thus, the purpose of this proposal is to deepen the study of the CZTS NPs layer, by itself and in a device, to understand the causes of this unusual efficiency enhancement, which could be related to the improved perovskite chemical stability.


The enhancement of efficiency in perovskite solar cells is achieved through the careful alignment of energy bands and the suppression of surface recombination processes. Our research delves into the impact of a tetra phenylethane derivative in addressing these concerns, resulting in an advancement of the device's fundamental properties. A comprehensive analysis of both electrical and optical characteristics of the resultant devices was conducted. This analysis revealed a noteworthy enhancement in multiple device parameters, emphasizing the positive effects of integrating the tetra phenylethane derivative into the perovskite (PSK) structure with a nip architecture. This integration led to an average efficiency surpassing 17% and 20% in single and triple cation-based systems, respectively, considering a 4 mm2 surface area. These promising findings establish a basis for subsequent investigations and optimizations of systems reliant on the tetra phenylethane derivative within perovskite solar cells. Nonetheless, the enduring challenges of ensuring the stability and scalability of perovskite solar cells remain significant hurdles that require effective resolutions for widespread commercial deployment and long-term viability. Consequently, this proposed research aims to systematically examine the elements influencing the stability and scalability of perovskite solar cells and to device strategies that elevate their performance and dependability.


Halide perovskites are versatile semiconductors that can be used in a variety of optoelectronic devices, including tandem solar cells in combination with silicon. Since the bandgap can be tuned through partial replacement of the constituents in the generic ABX3 structure, they are interesting for tandem devices, but they suffer from instability, e.g., through phase segregation. Interestingly, there appear to be compositions with higher stability, through an addition of Cl. In this project, the aim is to identify such combinations by creating combinatorial libraries with different Cl-sources and measuring them in an automated setup upon aging. As a result, the most stable compositions under accelerated aging will be identified.