TY - JOUR
T1 - Bromine Incorporation Affects Phase Transformations and Thermal Stability of Lead Halide Perovskites
AU - LaFollette, Diana K.
AU - Hidalgo, Juanita
AU - Allam, Omar
AU - Yang, Jonghee
AU - Shoemaker, Austin
AU - Li, Ruipeng
AU - Lai, Barry
AU - Lawrie, Benjamin
AU - Kalinin, Sergei
AU - Perini, Carlo A.R.
AU - Ahmadi, Mahshid
AU - Jang, Seung Soon
AU - Correa-Baena, Juan Pablo
N1 - Publisher Copyright:
© 2024 The Authors. Published by American Chemical Society.
PY - 2024
Y1 - 2024
N2 - Mixed-cation and mixed-halide lead halide perovskites show great potential for their application in photovoltaics. Many of the high-performance compositions are made of cesium, formamidinium, lead, iodine, and bromine. However, incorporating bromine in iodine-rich compositions and its effects on the thermal stability of the perovskite structure has not been thoroughly studied. In this work, we study how replacing iodine with bromine in the state-of-the-art Cs0.17FA0.83PbI3 perovskite composition leads to different dynamics in the phase transformations as a function of temperature. Through a combination of structural characterization, cathodoluminescence mapping, X-ray photoelectron spectroscopy, and first-principles calculations, we reveal that the incorporation of bromine reduces the thermodynamic phase stability of the films and shifts the products of phase transformations. Our results suggest that bromine-driven vacancy formation during high temperature exposure leads to irreversible transformations into PbI2, whereas materials with only iodine go through transformations into hexagonal polytypes, such as the 4H-FAPbI3 phase. This work sheds light on the structural impacts of adding bromine on thermodynamic phase stability and provides new insights into the importance of understanding the complexity of phase transformations and secondary phases in mixed-cation and mixed-halide systems.
AB - Mixed-cation and mixed-halide lead halide perovskites show great potential for their application in photovoltaics. Many of the high-performance compositions are made of cesium, formamidinium, lead, iodine, and bromine. However, incorporating bromine in iodine-rich compositions and its effects on the thermal stability of the perovskite structure has not been thoroughly studied. In this work, we study how replacing iodine with bromine in the state-of-the-art Cs0.17FA0.83PbI3 perovskite composition leads to different dynamics in the phase transformations as a function of temperature. Through a combination of structural characterization, cathodoluminescence mapping, X-ray photoelectron spectroscopy, and first-principles calculations, we reveal that the incorporation of bromine reduces the thermodynamic phase stability of the films and shifts the products of phase transformations. Our results suggest that bromine-driven vacancy formation during high temperature exposure leads to irreversible transformations into PbI2, whereas materials with only iodine go through transformations into hexagonal polytypes, such as the 4H-FAPbI3 phase. This work sheds light on the structural impacts of adding bromine on thermodynamic phase stability and provides new insights into the importance of understanding the complexity of phase transformations and secondary phases in mixed-cation and mixed-halide systems.
UR - http://www.scopus.com/inward/record.url?scp=85197223975&partnerID=8YFLogxK
U2 - 10.1021/jacs.4c04508
DO - 10.1021/jacs.4c04508
M3 - Article
C2 - 38935606
AN - SCOPUS:85197223975
SN - 0002-7863
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
ER -