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 effe...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±2cm^(2)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 Forster 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 optoelearonic applications.展开更多
基金We acknowledged Dr.Pio John S.Buenconsejo from the Facility for Analysis Characterization Testing and Simulation(FACTS),Nanyang Technological University,Singapore,for help with GI5AXS measurements.This research/project was supported by Nanyang Technological University under its start-up grants(M4080514,M4081630)the Ministry of Education under its AcRF Tier 1 grant(RG91/19)and Tier 2 grants(MOE2016-T2-1-034,MOE2017-T2-1-001,and MOE2017-T2-2-002)+1 种基金the National Research Foundation(NRF)Singapore under its NRF Investigatorship(NRF-NRFI-2018-04)Competitive Research Programme(NRF-CRP14-2014-03).
文摘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±2cm^(2)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 Forster 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 optoelearonic applications.
