Methylammonium Triiodide for Defect Engineering of High-Efficiency Perovskite Solar Cells
EA Alharbi and A Krishna and TP Baumeler and M Dankl and GC Fish and F Eickemeyer and O Ouellette and P Ahlawat and V Skorjanc and E John and BW Yang and L Pfeifer and CE Avalos and LF Pan and M Mensi and PA Schouwink and JE Moser and A Hagfeldt and U Rothlisberger and SM Zakeeruddin and M Gratzel, ACS ENERGY LETTERS, 6, 3650-3660 (2021).
The defects present in metal halide perovskite are deleterious to both the performance and stability of photovoltaic devices. Consequently, there is an intense focus on developing defect mitigation strategies. Herein we report a facile strategy that employs methylammonium triiodide (MAI(3)) as an additive to the perovskite precursor solution. We examine the effect of MAI(3) on the structural and optoelectronic properties by X-ray diffraction, density functional theory calculations, molecular dynamics simulations, solid-state nuclear magnetic resonance, steady- state, time-resolved photoluminescence (TRPL), and time-resolved terahertz spectroscopy (TRTS). Specifically, TRPL and TRTS show that MAI(3) suppresses nonradiative recombination and increases the charge carrier mobility. As a result, the champion device shows a power conversion efficiency (PCE) of 23.46% with a high fill factor of >80%. Furthermore, these devices exhibit enhanced operational stability, with the best device retaining similar to 90% of its initial PCE under 1 sun illumination with maximum power point tracking for 350 h.
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