Boosting exciton mobility approaching Mott-Ioffe-Regel limit in Ruddlesden−Popper perovskites by anchoring the organic cation

作者：Yiyang Gong, Shuai Yue, Yin Liang, Wenna Du, Tieyuan Bian, Chuanxiu Jiang, Xiaotian Bao, Shuai Zhang, Mingzhu Long, Guofu Zhou, Jun Yin, Shibin Deng, Qing Zhang, Bo Wu, Xinfeng Liu · 发表于：Nature Communications · 年份：2024 · DOI：10.1038/s41467-024-45740-y · 被引用次数：42 · 研究领域：Perovskite Materials and Applications、Quantum Dots Synthesis And Properties、2D Materials and Applications

Abstract Exciton transport in two-dimensional Ruddlesden−Popper perovskite plays a pivotal role for their optoelectronic performance. However, a clear photophysical picture of exciton transport is still lacking due to strong confinement effects and intricate exciton-phonon interactions in an organic-inorganic hybrid lattice. Herein, we present a systematical study on exciton transport in (BA) 2 (MA) n −1 Pb n I 3 n +1 Ruddlesden−Popper perovskites using time-resolved photoluminescence microscopy. We reveal that the free exciton mobilities in exfoliated thin flakes can be improved from around 8 cm 2 V −1 s −1 to 280 cm 2 V −1 s −1 by anchoring the soft butyl ammonium cation with a polymethyl methacrylate network at the surface. The mobility of the latter is close to the theoretical limit of Mott-Ioffe-Regel criterion. Combining optical measurements and theoretical studies, it is unveiled that the polymethyl methacrylate network significantly improve the lattice rigidity resulting in the decrease of deformation potential scattering and lattice fluctuation at the surface few layers. Our work elucidates the origin of high exciton mobility in Ruddlesden−Popper perovskites and opens up avenues to regulate exciton transport in two-dimensional materials.