EPFL is a Switzerland-based technical university and research center. EPFL is focused on three missions: teaching, research and technology transfer.
EPFL works together with an extensive network of partners including other universities and institutes of technology, secondary schools and colleges, industry and economy, political circles and the general public.
EPFL does extensive perovskite R&D work and is responsible for many publications and advancements in the field.
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Researchers tweak perovskite precursor solutions to produce useful cations that improve perovskite solar modules
Researchers from Ecole Polytechnique Fédérale de Lausanne (EPFL), North China Electric Power University, Westlake University, Lomonosov Moscow State University and others have described the addition of N,N-dimethylmethyleneiminium chloride ([Dmei]Cl) into perovskite precursor solutions to produce two cations in situ—namely 3-methyl-2,3,4,5-tetrahydro-1,3,5-triazin-1-ium ([MTTZ]+) and dimethylammonium ([DMA]+) cations - that enhanced the photovoltaic
performance and stability of perovskite solar modules.
A schematic of the roles of [MTTZ]+ and [DMA]+ in the 3D perovskite matrix. Image from: Science
The team explained that the in situ formation of [MTTZ]+ cation increased the formation energy of iodine vacancies and enhanced the migration energy barrier of iodide and cesium ions, which suppressed nonradiative recombination, thermal decomposition, and phase segregation processes.
Researchers develop optimization strategies that may pave the way towards industry-compatible, highly efficient tandem cells based on a production-compatible SHJ bottom cell
Researchers from Helmholtz Zentrum Berlin (HZB) and École Polytechnique Fédérale de Lausanne (EPFL) have presented optimization strategies for top cell processing and integration into silicon heterojunction (SHJ) bottom cells based on industrial Czochralski (Cz)-Si wafers of 140 μm thickness.
Schematic illustration of the perovskite/silicon tandem solar cell based on 140 μm Cz-Si. Image credit: ACS Applied Materials & Interfaces
The team showed that combining the self-assembled monolayer [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid (Me-4PACz) with an additional phosphonic acid (PA) with different functional groups, can improve film formation when used as a hole transport layer improving wettability, minimizing shunt fraction and reducing nonradiative losses at the buried interface.
Researchers introduce a new lead-halide-based Ruddlesden–Popper perovskite structure
Researchers from EPFL, University of Bern and HZB have introduced a new lead-halide-based Ruddlesden–Popper perovskite structure based on a visible-light-absorbing naphthalene-iminoimide cation. The team stated that the optoelectronic properties of this new material represent an important step toward enhancing light harvesting and affording the spatial separation of charge carrier transport in stable layered perovskite-based devices.
Incorporating organic semiconductor building blocks as spacer cations into layered hybrid perovskites provides an opportunity to develop new materials with novel optoelectronic properties, including nanoheterojunctions that afford spatial separation of electron and hole transport. However, identifying organics with suitable structure and electronic energy levels to selectively absorb visible light has been a challenge in the field. In their recent paper, the team introduced a new lead-halide-based Ruddlesden–Popper perovskite structure based on a visible-light-absorbing naphthalene-iminoimide cation (NDI-DAE).
Researchers develop a crystal capping layer to enable the formation of black-phase FAPbI3 perovskites in humid air
Researchers from Peking University, Tsinghua University, Beijing Institute of Technology and Ecole Polytechnique Fédérale de Lausanne (EPFL) have tackled a reproducibility challenge in black-phase formamidinium lead iodide (α-FAPbI3) perovskites. They explained that while this is the desired phase for photovoltaic applications, water can trigger formation of photoinactive impurity phases such as δ-FAPbI3. The team found that the classic solvent system for perovskite fabrication exacerbates this reproducibility issue.
Growth of the photoactive black phase of formamidinium lead iodide (α-FAPbI3) usually requires dimethyl sulfoxide solvent, but the hygroscopic nature of this chemical also promotes water-induced degradation to the photoinactive phase. the scientists showed that a larger chlorinated organic molecule can form a hydrophobic capping layer that enables perovskite crystallization under humid conditions by protecting growing crystallites from water.
Researchers use machine learning to accelerate the discovery of perovskite materials
Researchers at EPFL, Shanghai University and Université catholique de Louvain recently developed a method based on machine-learning to quickly and accurately search large databases, leading to the discovery of 14 new materials for solar cells.
The research project, led by EPFL's Haiyuan Wang and Alfredo Pasquarello, developed a method that combines advanced computational techniques with machine-learning to search for optimal perovskite materials for photovoltaic applications. The approach could lead to more efficient and cheaper solar panels, transforming solar industry standards.
