Open AccessPhase Segregation and Photothermal Remixing of Mixed-Halide Lead Perovskites
Author(s) -
Juvinch R. Vicente,
Jixin Chen
Publication year - 2020
Publication title -
the journal of physical chemistry letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.563
H-Index - 203
ISSN - 1948-7185
DOI - 10.1021/acs.jpclett.9b03734
Subject(s) - halide , photothermal therapy , phase (matter) , photoluminescence , photovoltaics , chemical physics , excitation , materials science , optoelectronics , nanotechnology , chemistry , photovoltaic system , inorganic chemistry , physics , organic chemistry , ecology , quantum mechanics , biology
Mixed-halide lead perovskites (MHPs) are promising materials for photovoltaics and optoelectronics due to their highly tunable band gaps. However, they phase segregate under continuous illumination or an electric field, the mechanism of which is still under debate. Herein we systematically measure the phase segregation behavior of polymer-encapsulated CH 3 NH 3 Pb(Br x I 1- x ) 3 MHPs as a function of excitation intensity and the nominal halide ratio by in situ photoluminescence microspectroscopy and observe surprising phase dynamics at the beginning of the illumination. The initial phase segregation to I-rich and Br-rich phases is observed followed by the formation of a new mixed-halide phase within several seconds that has not been reported before. We propose that the photothermal effect is amplified at the small-size I-rich domains, which significantly changes the local phase segregation in the otherwise uniform film within milliseconds after illumination.