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Probing the Spatial Heterogeneity of Carrier Relaxation Dynamics in CH 3 NH 3 PbI 3 Perovskite Thin Films with Femtosecond Time‐Resolved Nonlinear Optical Microscopy
Author(s) -
Yu Jin,
Li Zhongguo,
Liao Yuheng,
Kolodziej Charles,
Kuyuldar Seher,
Warren Warren S.,
Burda Clemens,
Fischer Martin C.
Publication year - 2019
Publication title -
advanced optical materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.89
H-Index - 91
ISSN - 2195-1071
DOI - 10.1002/adom.201901185
Subject(s) - materials science , photoluminescence , thin film , charge carrier , nanosecond , picosecond , femtosecond , relaxation (psychology) , perovskite (structure) , ultrafast laser spectroscopy , microscopy , molecular physics , optoelectronics , chemical physics , optics , nanotechnology , laser , crystallography , chemistry , physics , psychology , social psychology
Abstract The spatial heterogeneity of carrier dynamics in polycrystalline metal halide perovskite (MHP) thin films has a strong influence on photovoltaic device performance; however, the underlying cause is not yet clearly understood. Here, the sub‐micrometer scale mapping of charge carrier dynamics in CH 3 NH 3 PbI 3 thin films using time‐resolved nonlinear optical microscopy, specifically transient absorption microscopy (TAM) with sub‐picosecond (ps) and time‐resolved photoluminescence (PL) microscopy with nanosecond temporal resolution is reported. To study the influence of physical morphology on charge carrier dynamics, MHP thin films having granular‐ and fibrous structures are investigated. On both types of films, spatial regions with short‐lived transient gain signals (fast nonradiative relaxation within ≈1 ps) typically show slower charge recombination via radiative relaxation, which is attributed to the presence of additional energy states near the band edge. In addition, fibrous films show longer PL lifetimes. Interestingly, the functional contrast shown in TAM images exhibits fundamental differences from the structural contrast shown in scanning electron microscopy images, implying that the variation of trap density in the bulk contributes to the observed spatial heterogeneity in carrier dynamics.