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

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 >1 μm 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 Förster 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.Ministry of Education (MOE)National Research Foundation (NRF)Published versionWe acknowledged Dr. Pio John S. Buenconsejo from the Facility for Analysis Characterization Testing and Simulation (FACTS), Nanyang Technological University, Singapore, for help with GISAXS 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); and the National Research Foundation (NRF) Singapore under its NRF Investigatorship (NRF-NRFI-2018-04) and Competitive Research Programme (NRF-CRP14-2014-03). Author information Author notes These authors contributed equally: David Giovanni, Marcello Righetto Affiliations Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University (NTU), 21 Nanyang Link, Singapore, 637371, Singapore David Giovanni, Marcello Righetto, Qiannan Zhang, Jia Wei Melvin Lim, Sankaran Ramesh & Tze Chien Sum Energy Research Institute @NTU (ERI@N), Interdisciplinary Graduate School, Nanyang Technological University, 50 Nanyang Avenue, S2-B3a-01, Singapore, 639798, Singapore Jia Wei Melvin Lim & Sankaran Ramesh Contributions D.G. and M.R. conceived the idea. M.R. synthesized the samples. D.G. and M.R. performed the optical spectroscopy measurements and analysis of perovskite samples. Q.N. performed the AFM and GISAXS measurements and analysis. M.R. and J.W.M.L. performed the TEM measurement and analysis. D.G. and S.R. performed CdSe sample fabrication and measurement. T.C.S. led the project. All authors were involved in writing the manuscript. Corresponding author Correspondence to Tze Chien Sum. Ethics declarations Conflict of interest The authors declare that they have no conflict of interest. Supplementary information Supplementary Information for Origins of the Long-Range Exciton Diffusion in Perovskite Nanocrystal Films: Photon Recycling vs Exciton Hopping Rights and permissions Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. Reprints and Permissions About this article Verify currency and authenticity via CrossMark Cite this article Giovanni, D., Righetto, M., Zhang, Q. et al. Origins of the long-range exciton diffusion in perovskite nanocrystal films: photon recycling vs exciton hopping. Light Sci Appl 10, 2 (2021). https://doi.org/10.1038/s41377-020-00443-z Download citation Received19 July 2020 Revised13 November 2020 Accepted23 November 2020 Published01 January 2021 DOIhttps://doi.org/10.1038/s41377-020-00443-z Share this article Anyone you share the following link with will be able to read this content