An optical dynamic study of MAPbBr₃ single crystals passivated with MAPbCl₃/I₃-MAPbBr₃ heterojunctions

Abstract

Recently, perovskite based solar cells have attracted lots of research interest, some of which is in the passivation of perovskite surfaces, particularly the heterojunction based surface passivation. In this study, the optical dynamics of MAPbBr single crystals with and without heterojunction passivation were studied systematically by means of a time-resolved spectroscopic technique for the first time. The emission lifetime of MAPbBr single crystals under two-photon (1064 nm) excitation is a few orders of magnitude longer than that measured under one-photon (355 nm or 532 nm) excitation. Interestingly, with surface passivation, the lifetime measured at 355 nm excitations could be tuned significantly, whereas the lifetime change under 1064 nm excitations was considerably less. Our results give a direct evidence of surface quench by comparing the lifetimes before and after surface passivation. Furthermore, the results demonstrate that proper MAPbCl-MAPbBr heterojunctions can dramatically reduce the recombination channels in the surface region, which can be potentially useful for perovskite based solar cells, light emitting diodes (LED), and sensitive detectors.

Reversible air-induced optical and electrical modulation of methylammonium lead bromide (MAPbBr3) single crystals

“…The sharp peaks of MSC [ Fig. 4(a)] at 2h ¼ 6.65 , 13.3 , 20.05 , and 26.85 , consistent with the previously reported data, 45,48 represent a perfect MAPbBr 3 {001} surface with few defects. The normalized (100) peaks of MSC in air and vacuum are compared in Fig.…”

Recent Progress in Single‐Crystalline Perovskite Research Including Crystal Preparation, Property Evaluation, and Applications

“…Over the last 2 years, an increasing number of researchers have begun studying single‐crystalline perovskites, including crystal preparations,21, 27, 28, 43, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65 property studies,21, 27, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80 and applications 56, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91. For example, an extremely long carrier lifetime (up to 20 µs) and carrier diffusion length (175 µm) have been found,21 which has received a great deal of attention.…”

Amplified Spontaneous Emission Realized by Cogrowing Large/Small Grains with Self‐Passivating Defects and Aligning Transition Dipoles

“…The grain boundary defects are detrimental to realizing ASE: quenching light‐emitting states through nonradiative emission and preventing the coherent interaction between transition dipoles through Coulomb interaction . Generally, the grain boundary defects can be largely decreased by extrinsically doping with different dopants (such as chloride or potassium) through solution processing methods …”