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  • Ultrafast microscopy and image segmentation of spatially heterogeneous excited state and trap passivation in Cu2BaSnSSe3
Title: Ultrafast microscopy and image segmentation of spatially heterogeneous excited state and trap passivation in Cu2BaSnSSe3
Earth-abundant Cu2BaSnS4-xSex (CBTSSe) represents a recent alter- native for Cu2ZnSn(S,Se)4 for solar energy conversion with a lower level of disorder and band tailing. We report the heterogeneous excited-state and trap-state pattern in different solution-processed CBTSSe films using ultrafast two-color pump-probe diffuse reflec- tance microscopic imaging. The spectroscopy/microscopy method can visualize and correlate the microscopic compositional and elec- tronic variations (i.e., trap states) in real space with time-resolved photophysics. Heterogeneity patterns in TAM images show that some grains exhibit a positive excited-state absorption (ESA) signal, while others show negative ground-state bleaching (GSB). Our re- sults visualize that film processing, such as air annealing and Na addition, has a clear influence on the heterogeneity of the excited- state pattern. Importantly, we report stable charge carrier over 100 ps. We applied the image principal component and histogram for quantitative analysis of TAM images to deconvolute and visu- alize the contribution and fingerprints of minority free carriers and sub-band-gap trapped carriers.  more » « less
Award ID(s):
2239539
PAR ID:
10479194
Author(s) / Creator(s):
; ; ; ; ;
Publisher / Repository:
Cell Reports Physical Science
Date Published:
Journal Name:
Cell Reports Physical Science
Volume:
4
Issue:
10
ISSN:
2666-3864
Page Range / eLocation ID:
101601
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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