Origins of the long-range exciton diffusion in perovskite nanocrystal films: photon recycling vs exciton hopping

• 作者: David Giovanni Marcello Righetto Qiannan Zhang Jia Wei Melvin Lim Sankaran Ramesh Tze Chien Sum
• 来源期刊: 光：科学与应用（英文版）
• 年，卷（期）: 2021,（1）
• 所属期刊栏目: Articles
• 页码范围: 41-49
• 页数: 9页
• 语种: 英文

摘要

The outstanding optoelectronic performance of lead halide perovskites lies in their exceptional carrier diffusion properties. As the perovskite material dimensionality is reduced to exploit the quantum confinement effects, the disruption to the perovskite lattice, often with insulating organic ligands, raises new questions on the charge diffusion properties. Herein, we report direct imaging of >1μm exciton diffusion lengths in CH3NH3PbBr3 perovskite nanocrystal (PNC) films. Surprisingly, the resulting exciton mobilities in these PNC films can reach 10 ± 2 cm2 V-1 s-1, which is counterintuitively several times higher than the carrier mobility in 3D perovskite films. We show that this ultralong exciton diffusion originates from both efficient inter-NC exciton hopping (via F?rster energy transfer) and the photon recycling process with a smaller yet significant contribution. Importantly, our study not only sheds new light on the highly debated origins of the excellent exciton diffusion in PNC films but also highlights the potential of PNCs for optoelectronic applications.