Two-Factor Phase Separations in Mixed-Halide Quasi-2D Perovskite LEDs: Dimensionality and Halide Segregations

作者：Seok Joo Yang, Kang Wang, Yanqi Luo, Jee Yung Park, Hanjun Yang, Aidan H. Coffey, Ke Ma, Jiaonan Sun, Sarah Wieghold, Chenhui Zhu, Letian Dou · 发表于：ACS Energy Letters · 年份：2023 · DOI：10.1021/acsenergylett.3c01009 · 被引用次数：50 · 研究领域：Perovskite Materials and Applications、Quantum Dots Synthesis And Properties、Coral and Marine Ecosystems Studies

Quasi-2D halide perovskites have attracted much interest as a promising material for light-emitting diodes (LEDs) due to their tunability in quantum confinement and halide alloy formation to modulate the energy bandgap and emission color. However, two-factor phase separations with respect to heterogeneous quantum-well thicknesses and halide segregation are still crucial issues in quasi-2D perovskite LEDs, leading to low external quantum efficiencies (EQEs) and color shifts. Herein, we compare quasi-2D perovskite films using different cations to unveil the key contributions from the chemical design of organic cations. While mixing halide ions in conventional quasi-2D perovskite films induces micrometer-scale heterogeneity, new extended and twisted conjugated cations suppress the two-factor phase separations, leading to high EQEs of over 25% and controllable emission wavelengths across red and near-infrared regions. The fundamental insights in this work will provide guidance for advancing materials design and device performance in the future.