Established sequential deposition of multilayer two-terminal (2T) all-perovskite tandem solar cells possesses challenges for fabrication and limits the choice of materials and device architecture. In response, this work represents a lamination process based on a transparent and conductive adhesive that interconnects the wide-bandgap (WBG) perovskite top solar cell and the narrow-bandgap (NBG) perovskite bottom solar cell in a monolithic 2T all-perovskite tandem solar cell. The transparent conductive adhesive (TCA) layer combines Ag-coated poly(methyl methacrylate) microspheres with an optical adhesive. The TCA is employed as a recombination junction, achieving self-encapsulation with high transparency and good conductivity. A high vertical electrical conductivity is realized by optimizing the distribution of microspheres using a novel solidification strategy that employs UV curing and drying at 85 degrees C at low pressure. In addition, uniform and dense bilayer hole transport layers are realized by vapor-phase evaporation, which facilitates the application of the TCA and achieves pinhole-free buried interfaces in both the WBG perovskite top solar cell and the NBG perovskite bottom solar cell. Using these two strategies, losses in fill factor (FF) and open-circuit voltage (V OC) of the 2T all-perovskite tandem solar cell are reduced, achieving a respectable power conversion efficiency up to 18.2% for the lamination of the all-perovskite tandem solar cell. The laminated tandem solar cell retains similar to 93% of initial efficiency after exposure in ambient air (30-70 RH% and 20-35 degrees C) for similar to 30 days.

Vapor phase deposition methods are readily able to achieve uniform coverage of large-area substrates and are widely considered promising for industrial-scale perovskite solar cell fabrication. However, as perovskite-silicon tandem solar cells approach commercialization, practical considerations of manufacturing throughput come into play. Here, it is shown that the inherent sublimation characteristics of the organic precursor formamidinium iodide (FAI) make increasing the deposition rate of FA-based co-evaporated perovskites negatively impact replicability and lead to a substantial decrease in power conversion efficiency (PCE). These losses are linked to reduced film homogeneity and the emergence of carbon-rich regions within the perovskite layer. To mitigate these rate-induced effects, two approaches are explored: source layout optimization and material preconditioning. Utilizing dual FAI sources rather than a single FAI source reduces the relative PCE drop from approximate to 23%rel to approximate to 9%rel at a deposition rate of approximate to 18 nm min-1 (14.8% PCE @ maximum power point (MPP)) compared to the baseline rate of 5 nm min-1 (16.2% PCE @MPP). Alternatively, preconditioning a single FAI source reduces the performance losses from approximate to 31%rel to approximate to 26%rel at a deposition rate of approximate to 21 nm min-1. These findings underscore the importance of tailored source strategies to enable high-rate FA-based co-evaporated perovskites without compromising device performance.

Perovskite photovoltaics promise high power conversion efficiencies (PCEs) and cost‐effective fabrication, making them a transformative solar technology. Among deposition methods, the solution‐based two‐step process has emerged as a promising approach for integrating high‐quality perovskite layers onto silicon (Si) bottom cells, enabling dense and pinhole‐free films. However, achieving both high efficiency and long‐term stability remains underexplored for solution‐based two‐step‐processed perovskite solar cells (PSCs). This study introduces a versatile solution‐based two‐step method, demonstrating a seamless transition from a triple‐cation (CsMAFA) to a more stable double‐cation (CsFA) perovskite composition. Implementing a novel dual bimolecular passivation strategy with propane‐1,3‐diammonium iodide (PDAI 2 ) and n‐butylammonium iodide (BAI) for both bulk and surface passivation effectively addresses defects at grain boundaries and interfaces. This approach minimizes nonradiative recombination, enhances film crystallization, and promotes efficient charge extraction. The resulting PSCs demonstrate a stable power output of 20.9%, representing the highest reported efficiency for a solution‐based two‐step processed PSC with a bandgap of 1.67 eV. Laboratory‐scale monolithic perovskite/Si tandem solar cells (1 cm 2 active area) achieve PCEs exceeding 26% on small‐textured Si bottom cells (<2 μm). This emphasizes the potential of the solution‐based two‐step process for practical implementation in high‐performance photovoltaic systems.

Perovskite photovoltaics offer high power conversion efficiencies (PCEs) and low-cost manufacturing, making them a transformative solar technology. The solution-based two-step process has emerged as a promising method to deposit dense and pinhole-free perovskite top cells on silicon (Si) bottom cells. Commercial Si solar cells with microscale textures exhibit better light harvesting, paving the way for high-efficiency 2T perovskite/Si tandem solar cells (TSCs). However, long-term stability remains a major challenge for perovskite solar cells (PSCs). This study transitions from a triple cation (CsMAFA) to a double cation (CsFA) perovskite composition, achieving highly efficient PSCs with improved stability. Implementing a novel dual bimolecular passivation strategy for both bulk and surface passivation effectively addresses defects at grain boundaries and interfaces, resulting in a stable power output exceeding 20.9%. This represents the most efficient p-i-n type perovskite solar cell with a bandgap of 1.67 eV, processed by a two-step spin-coating method. Applied on textured Si bottom cells, this process achieves PCEs exceeding 24% for laboratory scale monolithic perovskite/Si TSCs.

Recent advances in sequential evaporation of perovskite solar cells (PSCs) have culminated in a rapid increase in reported power conversion efficiencies (PCEs), now on par with those of the best solution-processed counterparts. This development triggered vast interest from industry and academics. To date, however, very few studies addressed sequentially evaporated PSCs in the p-i-n architecture, and an in-depth process understanding is lacking. Here, we investigate the impact of the hole transport layer (HTL) on the formation of formamidinium lead triiodide (FAPI) perovskite thin films fabricated via an evaporated two-step process. We find that the crystal orientation of lead iodide (PbI2) changes significantly for different HTLs, thereby affecting the subsequent conversion and crystallization process. Adjusting the amount of deposited FAI reveals an unexpected correlation of the PbI2-to-perovskite X-ray diffraction peak intensity ratio to final PSC performance that depends on the employed HTL. Our approach enables PCEs of more than 17%, the highest reported for fully vacuum-processed pure FAPI PSCs in the p-i-n architecture.

Efficient p-i-n-based FAPbI3 perovskite solar cells for scalable solar modules and triple-junction photovoltaicsHang Hu a, b, David B. Ritzer a, b, Sophie X. An b, Yang Li a, b, Alexander Diercks b, Roja Singh a, b, Seyedamir Orooji a, b, Qihao Jin b, Paul Fassl a, b, Felix Laufer a, b, Thomas Feeney a, b, Ting Pan a, b, Bahram Abdollahi Nejand a, b, Ulrich W. Paetzold a, ba Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.b Light Technology Institute (LTI), Karlsruhe Institute of Technology (KIT), Engesserstrasse 13, 76131 Karlsruhe, Germany.International Conference on Hybrid and Organic PhotovoltaicsProceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV24)València, Spain, 2024 May 12th - 15thOrganizer: Bruno EhrlerOral, Hang Hu, presentation 033DOI: https://doi.org/10.29363/nanoge.hopv.2024.033Publication date: 6th February 2024Formamidinium lead iodide (FAPbI3) emerges as one of the most promising materials for perovskite solar cells (PSCs) with high power conversion efficiency (PCE) and good stability. However, (i) the scalability lags behind and only a few reports have been dedicated so far towards the scalable processing of FAPbI3 perovskite solar modules; (ii) FAPbI3 has not been applied in multi-junction solar cells and the performance of perovskite–perovskite–silicon triple-junction solar cells lag considerably behind with only a limited number of reports on prototypes. First, this study reports void-free, α-phase, and high-quality FAPbI3 thin films processed via vacuum-assisted growth (VAG) method in p-i-n-based PSCs. VAG eliminates interfacial voids at the buried interface of hole-transport layer (HTL)/FAPbI3, enabling a high PCE of 22.3% for p-i-n-based PSCs. We demonstrate that the voids result in non-radiative recombination loss (i.e., open-circuit voltage (VOC) loss) and poor charge extraction (i.e., low current density (JSC)). An innovative combination of employing methylammonium chloride (MACl) as an additive and applying a moderate N2-flow during the VAG process facilitates blade coating homogeneous large-area FAPbI3 thin films without interfacial voids. As a result, scalable PSCs (0.105 cm2) and mini-modules (aperture area of 12.25 cm2, geometrical fill factor of 96.3%) with PCEs of 20.0% and 18.3% are achieved, respectively. Second, this study addresses significant challenges in processing triple junctions in which the most critical junction is the middle perovskite sub-cell. We present triple-junction perovskite–perovskite–silicon solar cells achieving an unprecedented PCE of 24.4%. Through the optimization of light management for each perovskite sub-cell (with bandgaps of ~1.84 eV and ~1.52 eV for the top and middle cells, respectively), the current generation is maximized to 11.6 mA cm–2. The key to this achievement is the development of a high-performance middle perovskite sub-cell, utilizing a stable pure-α-phase FAPbI3 perovskite thin film that is free of wrinkles, cracks, and pinholes. This enables a high VOC of 2.84 V in the triple-junction architecture. Notably, non-encapsulated triple-junction devices retain up to 96.6% of their initial efficiency when stored in the dark at 85°C for 1081 hours. These are remarkable advances in upscaling FAPbI3-based PSCs and multi-junction PVs. References:[1] H. Hu, D. B. Ritzer, A. Diercks, Y. Li, R. Singh, P. Fassl, Q. Jin, F. Schackmar, U. W. Paetzold and B. Abdollahi Nejand, Joule, 2023, 7, 1574–1592.Acknowledgements:Financial support from the Initiating and Networking funding of Helmholtz Association HYIG of U.W.P. (VH-NG-1148), the Helmholtz Energy Materials Foundry (HEMF), and Karlsruhe School of Optics and Photonics (KSOP) is gratefully acknowledged. The authors acknowledge the Helmholtz Association (program-oriented funding IV, Materials and Technologies for the Energy Transition, Topic 1: Photovoltaics and Wind Energy, Code: 38.01.02). B.A.N. acknowledges the financial support from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie (grant agreement no. 840937). H.H. acknowledges the Chinese Scholarship Council (CSC, no. 201808420221) for funding his doctoral research work. © FUNDACIO DE LA COMUNITAT VALENCIANA SCITOnanoGe is a prestigious brand of successful science conferences that are developed along the year in different areas of the world since 2009. Our worldwide conferences cover cutting-edge materials topics like perovskite solar cells, photovoltaics, optoelectronics, solar fuel conversion, surface science, catalysis and two-dimensional materials, among many others.MATSUSPreviously nanoGe Spring Meeting (NSM) and nanoGe Fall Meeting (NFM), MATSUS is a multiple symposia conference focused on a broad set of topics of advanced materials preparation, their fundamental properties, and their applications, in fields such as renewable energy, photovoltaics, lighting, semiconductor quantum dots, 2-D materials synthesis, charge carriers dynamics, microscopy and spectroscopy semiconductors fundamentals, etc.International Conference on Hybrid and Organic PhotovoltaicsInternational Conference on Hybrid and Organic Photovoltaics (HOPV) is celebrated yearly in May. The main topics are the development, function and modeling of materials and devices for hybrid and organic solar cells. The field is now dominated by perovskite solar cells but also other hybrid technologies, as organic solar cells, quantum dot solar cells, and dye-sensitized solar cells and their integration into devices for photoelectrochemical solar fuel production.Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and OptoelectronicsThe main topics of the Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics (IPEROP) are discussed every year in Asia-Pacific for gathering the recent advances in the fields of material preparation, modeling and fabrication of perovskite and hybrid and organic materials. Photovoltaic devices are analyzed from fundamental physics and materials properties to a broad set of applications. The conference also covers the developments of perovskite optoelectronics, including light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and OptoelectronicsThe International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics (NIPHO) is the best place to hear the latest developments in perovskite solar cells as well as on recent advances in the fields of perovskite light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.

Impact of materials stoichiometry and surface morphology on stability of perovskite solar cellsRoja Singh a, b, Hang Hu a, b, Thomas Feeney b, Alexander Diercks b, Felix Laufer b, Yang Li a, b, The Duong c, Fabian Schackmar a, b, Bahram A. Nejand a, b, Ulrich W. Paetzold a, ba Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.b Light Technology Institute (LTI), Karlsruhe Institute of Technology (KIT), Engesserstrasse 13, 76131 Karlsruhe, Germany.c School of Engineering, The Australian National University, Canberra 2601, AustraliaInternational Conference on Hybrid and Organic PhotovoltaicsProceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV24)València, Spain, 2024 May 12th - 15thOrganizer: Bruno EhrlerOral, Roja Singh, presentation 050DOI: https://doi.org/10.29363/nanoge.hopv.2024.050Publication date: 6th February 2024Long-term stability of perovskite solar cells (PSC) is the impending bottleneck for commercialization of the technology in the renewable energy sector. In this work, we critically assess effects of material stoichiometry and surface morphology to understand their impact on the long-term stability of caesium-formamidinium-based PSC. Key findings demonstrate that the variation in the perovskite precursor - lead iodide (PbI2) to formamidinium iodide (FAI) ratio impacts the stability under various stress conditions (elevated temperature and light). A high molar ratio PbI2/FAI >1.1 in the perovskite precursor contributes to a higher open-circuit voltage (VOC) and hence better power conversion efficiency (PCE). However, the quenching techniques (anti-solvent and vacuum quenching) during the processing do not affect the long-term stability of PSCs. When tested under ISOS-D2 (dark, 85 °C, intermittent current density-voltage J-V characterization) condition, the degradation of the perovskite layer or interfaces between the perovskite layer and the charge transport layers lead to a decrease in performance for the devices implementing non-standard PbI2/FAI ratio (>1.1 or <1.1) over a period of 500 h. Under ISOS-L1 (100 mW/cm2, 25 °C, maximum power point tracking) condition, the devices with PbI2/FAI ≤1.1 remain stable over 500 h whereas devices with PbI2/FAI >1.1 show a drastic drop in J. Interestingly, we observe a contradictory trend in post-degradation analysis of devices stressed under ISOS-L1. The devices with PbI2/FAI ≤1.1 are stable under stress but their PCEs begin to decrease during storage in dark as characterized by intermittent J-V. The presence of iodide vacancies (VI-) in the absorber layer results in non-radiative recombination and migration of iodide ions (I-) to the hole transport layer causes formation of shunts during storage in the dark. This work highlights the importance of reporting stability under different stress conditions as well as post-degradation and dark recovery analysis of PSCs to understand a process as complex as perovskite instability. Acknowledgements:Financial support by the Initiating and Networking funding of the Helmholtz Association (Project Zeitenwende and the Solar Technology Acceleration Platform (Solar TAP)), the program-oriented funding IV of the Helmholtz Association (Materials and Technologies for the Energy Transition, Topic 1: Photovoltaics and Wind Energy, Code: 38.01.04), the German Federal Ministry for Economic Affairs and Climate Action (BMWK) through the projects 27Plus6 (03EE1056B) and SHAPE (03EE1123A), and the Karlsruhe School of Optics and Photonics (KSOP) is gratefully acknowledged. The authors thank the whole "perovskite task force" at KIT for fruitful discussions and assistance. © FUNDACIO DE LA COMUNITAT VALENCIANA SCITOnanoGe is a prestigious brand of successful science conferences that are developed along the year in different areas of the world since 2009. Our worldwide conferences cover cutting-edge materials topics like perovskite solar cells, photovoltaics, optoelectronics, solar fuel conversion, surface science, catalysis and two-dimensional materials, among many others.MATSUSPreviously nanoGe Spring Meeting (NSM) and nanoGe Fall Meeting (NFM), MATSUS is a multiple symposia conference focused on a broad set of topics of advanced materials preparation, their fundamental properties, and their applications, in fields such as renewable energy, photovoltaics, lighting, semiconductor quantum dots, 2-D materials synthesis, charge carriers dynamics, microscopy and spectroscopy semiconductors fundamentals, etc.International Conference on Hybrid and Organic PhotovoltaicsInternational Conference on Hybrid and Organic Photovoltaics (HOPV) is celebrated yearly in May. The main topics are the development, function and modeling of materials and devices for hybrid and organic solar cells. The field is now dominated by perovskite solar cells but also other hybrid technologies, as organic solar cells, quantum dot solar cells, and dye-sensitized solar cells and their integration into devices for photoelectrochemical solar fuel production.Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and OptoelectronicsThe main topics of the Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics (IPEROP) are discussed every year in Asia-Pacific for gathering the recent advances in the fields of material preparation, modeling and fabrication of perovskite and hybrid and organic materials. Photovoltaic devices are analyzed from fundamental physics and materials properties to a broad set of applications. The conference also covers the developments of perovskite optoelectronics, including light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and OptoelectronicsThe International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics (NIPHO) is the best place to hear the latest developments in perovskite solar cells as well as on recent advances in the fields of perovskite light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.

Enhancing reproducibility, repeatability, as well as facilitating transferability between laboratories will accelerate the progress in many material domains, wherein perovskite-based optoelectronics are a prime use case. This study presents fully automated perovskite thin film processing using a commercial spin-coating robot in an inert atmosphere. We successfully apply this novel processing method to antisolvent quenching. This process is typically difficult to reproduce and transfer and is now enhanced to exceptional repeatability in comparison to manual processing. Champion perovskite solar cells demonstrate power conversion efficiencies as high as 19.9%, proving the transferability of established manual spin-coating processes to automatic setups. Comparison with human experts reveals that the performance is already on par, while automated processing yields improved homogeneity across the substrate surface. This work demonstrates that fully automated perovskite thin film processing improves repeatability. Such systems bear the potential to become a foundation for autonomous optimization and greatly improve transferability between laboratories.

Understanding Substrate-Dependent Growth of Sequentially Evaporated Perovskite Thin FilmsAlexander Diercks a, Julian Petry b, Thomas Feeney a, Roja Singh a, Ulrich W. Paetzold a, b, Paul Fassl a, ba Light Technology Institute (LTI) at Karlsruhe Institute of Technology (KIT), Karlsruhe, Engesserstr. 13, 76131, Germanyb Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.International Conference on Hybrid and Organic PhotovoltaicsProceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV24)València, Spain, 2024 May 12th - 15thOrganizer: Bruno EhrlerOral, Alexander Diercks, presentation 115DOI: https://doi.org/10.29363/nanoge.hopv.2024.115Publication date: 6th February 2024Perovskite solar cells (PSCs) are a promising candidate for next-generation photovoltaics, demonstrating remarkable advances in performance during the last decade, with record power conversion efficiencies (PCEs) exceeding 26%. Vacuum deposition techniques are widely used for fabrication of thin-films and have several advantages compared to solution-based fabrication methods. These include conformal deposition of high-quality layers, low material consumption and the ease of scalability to larger areas. However, PCEs of thermally evaporated PSCs have been lacking behind those of solution-processed PSCs for years. While originally most research regarding thermally evaporated PSCs was dedicated to co-evaporation processes, reaching maximum PCEs of 20.6%,[1] recent record n-i-p PCEs > 21% were achieved via sequential (two-step) layer deposition approaches.[2,3] Here, the individual perovskite precursors are deposited in two steps and converted to the final perovskite film during a subsequent annealing step. In this work, we present a sequential evaporation process to fabricate all-vacuum-processed methylammonium-free PSCs in the p-i-n architecture. In the first process step, the inorganic layer is deposited onto the substrate, followed by the deposition of formamidinium iodide (FAI) in the second evaporation step. The conversion of these two layers into the final perovskite film is performed during an optimized annealing step under ambient atmosphere. We will present phase-pure formamidinium lead iodide (FAPI) PSCs using an all-vacuum-processed layer stack with PCEs above 16%, among the highest reported for evaporated FAPI PSCs in the p-i-n architecture. Interestingly, we observe a significant difference in X-ray diffraction measurements of the final perovskite thin film when changing the underlying hole transport layer (HTL). Further experiments demonstrate variations in microstructure and morphology of the inorganic layer on various HTLs, which impact the interaction with FAI and the conversion into a perovskite film. Proving this substrate-dependent film growth and understanding how to manipulate the microstructure/morphology of the inorganic layer by adjusting process parameters during the evaporation marks a huge step forward in understanding the sequential evaporation process. We will discuss these findings at the conference. Furthermore, addition of further inorganic precursor materials (lead bromide, caesium iodide, caesium bromide) in the first evaporation step allows adjusting the bandgap, facilitating fabrication of efficient wide-bandgap PSCs and perovskite-based tandem solar cells. Our work paves the way for efficient all-evaporated PSCs and their application to monolithic tandem solar cells with an up-scalable and industrially relevant deposition technique. References:[1] Ross, Marcel, et al. "Co-evaporated pin perovskite solar cells beyond 20% efficiency: impact of substrate temperature and hole-transport layer." ACS applied materials & interfaces 12.35 (2020): 39261-39272[2] Feng, Jiangshan, et al. "High-throughput large-area vacuum deposition for high-performance formamidine-based perovskite solar cells." Energy & Environmental Science 14.5 (2021): 3035-3043[3] Li, Hang, et al. "Sequential vacuum-evaporated perovskite solar cells with more than 24% efficiency." Science Advances 8.28 (2022): eabo7422[4] Farag, Ahmed, et al. "Evaporated Self‐Assembled Monolayer Hole Transport Layers: Lossless Interfaces in p‐i‐n Perovskite Solar Cells." Advanced Energy Materials: 2203982Acknowledgements:We thank the German Federal Ministry for Economics and Climate Action (BMWK) through the project SHAPE (03EE1123A). © FUNDACIO DE LA COMUNITAT VALENCIANA SCITOnanoGe is a prestigious brand of successful science conferences that are developed along the year in different areas of the world since 2009. Our worldwide conferences cover cutting-edge materials topics like perovskite solar cells, photovoltaics, optoelectronics, solar fuel conversion, surface science, catalysis and two-dimensional materials, among many others.MATSUSPreviously nanoGe Spring Meeting (NSM) and nanoGe Fall Meeting (NFM), MATSUS is a multiple symposia conference focused on a broad set of topics of advanced materials preparation, their fundamental properties, and their applications, in fields such as renewable energy, photovoltaics, lighting, semiconductor quantum dots, 2-D materials synthesis, charge carriers dynamics, microscopy and spectroscopy semiconductors fundamentals, etc.International Conference on Hybrid and Organic PhotovoltaicsInternational Conference on Hybrid and Organic Photovoltaics (HOPV) is celebrated yearly in May. The main topics are the development, function and modeling of materials and devices for hybrid and organic solar cells. The field is now dominated by perovskite solar cells but also other hybrid technologies, as organic solar cells, quantum dot solar cells, and dye-sensitized solar cells and their integration into devices for photoelectrochemical solar fuel production.Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and OptoelectronicsThe main topics of the Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics (IPEROP) are discussed every year in Asia-Pacific for gathering the recent advances in the fields of material preparation, modeling and fabrication of perovskite and hybrid and organic materials. Photovoltaic devices are analyzed from fundamental physics and materials properties to a broad set of applications. The conference also covers the developments of perovskite optoelectronics, including light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and OptoelectronicsThe International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics (NIPHO) is the best place to hear the latest developments in perovskite solar cells as well as on recent advances in the fields of perovskite light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.

The long-term stability of perovskite solar cells (PSCs) remains a bottleneck for commercialization. While studies on the stoichiometry and morphology of PSCs with regard to performance are prevalent, understanding the influence of these factors on their long-term stability is lacking. In this work, we evaluate the impact of stoichiometry and morphology on the long-term stability of cesium formamidinium-based PSCs. We demonstrate that the lead iodide (PbI2) to formamidinium iodide (FAI) ratio influences stability under various stress factors (elevated temperature and light). A high molar ratio (PbI2/FAI > 1.1) in the perovskite precursor displays drastic degradation under ISOS-L1 (100 mW/cm2, 25 °C, maximum power point tracking) conditions. However, postdegradation analysis contradicts these results. Devices with PbI2/FAI ≤ 1.1 are stable under light, but intermittent current density-voltage characterizations indicate that device performance decreases during storage in the dark. Migration of iodide (I-) ions to the electron-transport layer (ETL) and iodine vacancies (VI-+) to the hole-transport layer (HTL) forms localized shunts in the absorber layer. Pinhole formation, surrounded by FA+-rich regions, explains the extent of damage in comparably aged films. In summary, this work emphasizes the importance of reporting stability under different stress conditions, coupled with postdegradation and dark recovery analyses of PSCs to better understand the complexities of perovskite instability under real-life conditions such as expected during outdoor operation.

The recent tremendous progress in monolithic perovskite-based double-junction solar cells is just the start of a new era of ultra-high-efficiency multi-junction photovoltaics. We report on triple-junction perovskite-perovskite-silicon solar cells with a record power conversion efficiency of 24.4%. Optimizing the light management of each perovskite sub-cell (∼1.84 and ∼1.52 eV for top and middle cells, respectively), we maximize the current generation up to 11.6 mA cm-2. Key to this achievement was our development of a high-performance middle perovskite sub-cell, employing a stable pure-α-phase high-quality formamidinium lead iodide perovskite thin film (free of wrinkles, cracks, and pinholes). This enables a high open-circuit voltage of 2.84 V in a triple junction. Non-encapsulated triple-junction devices retain up to 96.6% of their initial efficiency if stored in the dark at 85 °C for 1081 h.

Abstract Optical interference filters (OIFs) are vital components for a wide range of optical and photonic systems. They are pivotal in controlling spectral transmission and reflection upon demand. OIFs rely on optical interference of the incident wave at multilayers, which are fabricated with nanometer precision. Here, we demonstrate that these requirements can be fulfilled by inkjet printing. This versatile technology offers a high degree of freedom in manufacturing, as well as cost-affordable and rapid-prototyping features from the micron to the meter scale. In this work, via rational ink design and formulation, OIFs were fully inkjet printed in ambient conditions. Longpass, shortpass, bandpass, and dichroic OIFs were fabricated, and precise control of the spectral response in OIFs was realized. Subsequently, customized lateral patterning of OIFs by inkjet printing was achieved. Furthermore, upscaling of the printed OIFs to A4 size (29.7 × 21.0 cm²) was demonstrated.

Formamidinium lead iodide (FAPbI3) has emerged as one of the most promising perovskite semiconductors for perovskite solar cells (PSCs), demonstrating high power conversion efficiency (PCE) and good stability. However, only a few reports address the scalable processing and fabrication of FAPbI3 perovskite solar modules. Here, we report a void-free perovskite-buried interface in p-i-n-based PSCs, which enables us to upscale lab-scale solar cells (<1 cm2) to mini-module dimensions (>10 cm2). An innovative combination of a moderate N2 flow during vacuum-assisted growth (VAG) control of the perovskite thin films as well as the employment of MACl as an additive eliminates interfacial voids in blade-coated large-area FAPbI3 layers, enabling respective PCEs of 20.0% and 18.3% in blade-coated PSCs (0.105 cm2) and fully scalable modules (aperture area of 12.25 cm2 and geometric fill factor of 96.3%). This is a remarkable advance in upscaling FAPbI3-based perovskite photovoltaics.

Engineering of the interface between perovskite absorber thin films and charge transport layers has fueled the development of perovskite solar cells (PSCs) over the past decade. For p‐i‐n PSCs, the development and adoption of hole transport layers utilizing self‐assembled monolayers (SAM‐HTLs) based on carbazole functional groups with phosphonic acid anchoring groups has enabled almost lossless contacts, minimizing interfacial recombination to advance power conversion efficiency in single‐junction and tandem solar cells. However, so far these materials have been deposited exclusively via solution‐based methods. Here, for the first time, vacuum‐based evaporation of the most common carbazole‐based SAM‐HTLs (2PACz, MeO‐2PACz, and Me‐4PACz) is reported. X‐ray photoelectron spectroscopy and infrared spectroscopy demonstrate no observable chemical differences in the evaporated SAMs compared to solution‐processed counterparts. Consequently, the near lossless interfacial properties are either preserved or even slightly improved as demonstrated via photoluminescence measurements and an enhancement in open‐circuit voltage. Strikingly, applying evaporated SAM‐HTLs to complete PSCs demonstrates comparable performance to their solution‐processed counterparts. Furthermore, vacuum deposition is found to improve perovskite wetting and fabrication yield on previously non‐ideal materials (namely Me‐4PACz) and to display conformal and high‐quality coating of micrometer‐sized textured surfaces, improving the versatility of these materials without sacrificing their beneficial properties.

Vacuum‐assisted growth (VAG) control is one of the most promising methods for controlling nucleation and crystallization of printed and coated large area lead halide perovskite‐based layers for optoelectronics. To coat or print homogeneous high‐quality perovskite thin‐films at high fabrication yield, real‐time process monitoring of the VAG is pivotal. In response, a 2.1‐megapixel multichannel photoluminescence (PL) and reflection imaging system is developed and employed for the simultaneous spatial in situ analysis of drying, nucleation, and crystal growth during VAG and subsequent thermal annealing of inkjet‐printed and blade‐coated perovskite thin‐films. It is shown that the VAG process, for example, evacuation rate and time, affects the film formation and provide detailed insight into traced PL and reflection transients extracted from sub‐second videos of each channel. Based on correlative analysis between the transients and, for example, perovskite ink composition, wet‐film thickness, or evacuation time, key regions which influence crystal quality, film morphology, and are base for prediction of solar cell performance are identified.

Monolithic two-terminal (2T) perovskite/CuInSe2 (CIS) tandem solar cells (TSCs) combine the promise of an efficient tandem photovoltaic (PV) technology with the simplicity of an all-thin-film device architecture that is compatible with flexible and lightweight PV. In this work, we present the first-ever 2T perovskite/CIS TSC with a power conversion efficiency (PCE) approaching 25% (23.5% certified, area 0.5 cm2). The relatively planar surface profile and narrow band gap (∼1.03 eV) of our CIS bottom cell allow us to exploit the optoelectronic properties and photostability of a low-Br-containing perovskite top cell as revealed by advanced characterization techniques. Current matching was attained by proper tuning of the thickness and bandgap of the perovskite, along with the optimization of an antireflective coating for improved light in-coupling. Our study sets the baseline for fabricating efficient perovskite/CIS TSCs, paving the way for future developments that might push the efficiencies to over 30%.

Monolithic all-perovskite tandem photovoltaics promise to combine low-cost and high-efficiency solar energy harvesting with the advantages of all-thin-film technologies. To date, laboratory-scale all-perovskite tandem solar cells have only been fabricated using non-scalable fabrication techniques. In response, this work reports on laser-scribed all-perovskite tandem modules processed exclusively with scalable fabrication methods (blade coating and vacuum deposition), demonstrating power conversion efficiencies up to 19.1% (aperture area, 12.25 cm 2 ; geometric fill factor, 94.7%) and stable power output. Compared to the performance of our spin-coated reference tandem solar cells (efficiency, 23.5%; area, 0.1 cm 2 ), our prototypes demonstrate substantial advances in the technological readiness of all-perovskite tandem photovoltaics. By means of electroluminescence imaging and laser-beam-induced current mapping, we demonstrate the homogeneous current collection in both subcells over the entire module area, which explains low losses (<5% rel ) in open-circuit voltage and fill factor for our scalable modules.