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Low Pressure Vapor-assisted Solution Process for Tunable Band Gap Pinhole-free Methylammonium Lead Halide Perovskite Films
Published on: September 8, 2017
Low-dimensional templates and delayed crystallization for high-quality tin-based perovskite films and
Yanqiu Wu1,2, Shuzhang Yang1, Enlong Li1
1State Key Laboratory of Photovoltaic Science and Technology, Institute of Optoelectronics, College of Future Information Technology, Fudan University, Shanghai, China.
None:
Quasi-2D tin-based perovskites are promising p-type semiconductors due to their thermodynamic stability and suppressed ion migration tendencies. However, the competitive growth of low- and high-dimensional phases leads to pronounced structural disorder, increased defect density, and poor crystallographic orientation, thereby restricting charge transport. Here, phenethylammonium thiocyanate (PEASCN) is incorporated into the precursor to promote the preferential formation of PEA2FAn-1SnnI3n-1SCN2 (n = 2) templates. Substituting formamidinium iodide (FAI) with formamidinium formate (FAHCOO) and ammonium iodide (NH4I) suppresses the uncontrollable growth of 3D FASnI3 at room temperature, enabling precise crystallization control. These low-dimensional templates guide the growth of high-dimensional phases upon annealing, yielding vertically oriented films with reduced defects. The fabricated field-effect transistors exhibit mobility up to 43 cm2 V-1 s-1 and an on/off ratio exceeding 108, alongside nearly negligible hysteresis and enhanced stability. These results demonstrate a viable approach for regulating crystallization kinetics and realizing high-performance, stable tin-based perovskite devices.

