Exceptional Morphology-Preserving Evolution of Formamidinium Lead Triiodide Perovskite Thin Films via Organic-Cation Displacement

Abstract

Here we demonstrate a radically different chemical route for the creation of HC(NH 2 ) 2 PbI 3 (FAPbI 3 ) perovskite thin films. This approach entails a simple exposure of as-synthesized CH 3 NH 3 PbI 3 (MAPbI 3 ) perovskite thin films to HC(NH)NH 2 (formamidine or FA) gas at 150°C, which leads to rapid displacement of the MA + cations by FA + cations in the perovskite structure. The resultant FAPbI 3 perovskite thin films preserve the microstructural morphology of the original MAPbI 3 thin films exceptionally well. Importantly, the myriad processing innovations that have led to the creation of highquality MAPbI 3 perovskite thin films are directly adaptable to FAPbI 3 through this simple, rapid chemical-conversion route. Accordingly, we show that efficiencies of perovskite solar cells fabricated with FAPbI 3 thin films created using this route can reach ∼18%.

Alkali Metal Doping for Improved CH3NH3PbI3 Perovskite Solar Cells

“…and X is a monovalent anion (Cl − , Br − , I − , SCN − etc.) have attracted great attention owing to their superior photoelectronic properties 1, 2, 3, 4, 5. As a type of star material in the photovoltaic field, the performance of perovskite‐based thin film solar cells have gone through tremendous advance, almost caught up with or even gone beyond the efficiency of crystalline silicon, CIGSe (copper–indium–gallium diselenide) and CdTe solar cells only in a few years 1, 6, 7, 8, 9, 10.…”

Combination of Hybrid CVD and Cation Exchange for Upscaling Cs‐Substituted Mixed Cation Perovskite Solar Cells with High Efficiency and Stability

“…[60][61][62][63][64][65] Here, we propose a method combining hybrid CVD and cation exchange (HCVD-CE) to prepare Cs x FA 1−x PbI 3 mixed perovskite that can take advantage of both enhanced perovskite stability and upscaling compatibility. Because the whole process only uses large-area compatible steps (namely, non-anti-solvent spin-coating, CVD, and cation exchange), it can significantly minimize the effort required for industrialization in the future.…”

Heterojunction‐Depleted Lead‐Free Perovskite Solar Cells with Coarse‐Grained B‐γ‐CsSnI3 Thin Films

“…[1][2][3][4][5][6] Halide perovskite materials that are adopted as light absorbers in PSCs have outstanding optoelectronic properties, such as high absorption coefficient, long-range charge diffusion lengths, low exciton binding energies, high carrier mobilities, and suitable bandgaps. [1][2][3][4][5][6] However, there are some intrinsic issues associated with the use of the MAPbI 3 or FAPbI 3 perovskite. To date, most studies have focused on using hybrid organic-inorganic halide perovskites, in particular methylammonium lead triiodide (MAPbI 3 ) and formamidinium lead triiodide (FAPbI 3 ), as light absorbers in PSCs, where high PCEs have been achieved through the optimization of cell architectures and structures of the perovskite absorber layers.…”