Composition Engineering in Two-Dimensional Pb–Sn-Alloyed Perovskites for Efficient and Stable Solar Cells
2018
Chen, Yani | Sun, Yong | Peng, Jiajun | Chábera, Pavel | Honarfar, Alireza | Zheng, Kaibo | Liang, Ziqi
Environmentally friendly tin (Sn)-based metallic halide perovskites suffer from oxidation and morphological issues. Here, we demonstrate the composition engineering of Pb–Sn-alloyed two-dimensional (2D) Ruddlesden–Popper perovskites, (BA)₂(MA)₃Pb₄–ₓSnₓI₁₃, for efficient and stable solar cell applications. Smooth thin films with high surface coverage are readily formed without using any additive owing to the self-assembly characteristic of 2D perovskites. It is found that Sn plays a significant role in improving the crystallization and crystal orientation while narrowing the bandgap of Pb–Sn 2D perovskites. Photophysical studies further reveal that the optimal Sn ratio (25 mol %) based sample exhibits both minimized trap density and weakened quantum confinement for efficient charge separation. Consequently, the optimized (BA)₂(MA)₃Pb₃SnI₁₃-based solar cells yield the best power conversion efficiency close to 6% with suppressed hysteresis.
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