Professor Gustavo Dalpian

@article{https://doi.org/10.1002/aenm.202301539,

title = {Light-Induced Frenkel Defect Pair Formation Can Lead to Phase-Segregation of Otherwise Miscible Halide Perovskite Alloys},

author = {Fernando P. Sabino and Gustavo M. Dalpian and Alex Zunger},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/aenm.202301539},

doi = {https://doi.org/10.1002/aenm.202301539},

year  = {2023},

date = {2023-10-11},

journal = {Advanced Energy Materials},

volume = {n/a},

number = {n/a},

pages = {2301539},

abstract = {Abstract Alloys of ABX3 halide perovskites (HP) exhibit unique phase behavior compared to traditional III-V and II-VI semiconductor alloys used in solar cells. While the latter typically have good mutual miscibility when their mixed components are size matched, and phase-segregate when size mismatched, HP alloys show good miscibility in the dark but can phase-segregate under light. Quantum mechanical calculations described herein reveal light-induced defect formation and migration hold the key. Specifically, the interaction between a halogen vacancy VX with halogen interstitial Xi forming together a Frenkel-pair defect emerges as the enabler for phase-segregation in HP alloys. At a threshold bromine composition in the Br-I alloys, the photogenerated holes in the valence band localize, creating thereby a doubly-charged iodine Frenkel-pair (VI + Ii)2+. Faster migration of iodine over bromine interstitial into the vacant iodine VI site leads to the formation of iodine-rich and iodine-depleted regions, establishing phase-segregation. Removal of the mobile defects–the agent of segregation–by dark thermal annealing, supplies the opposing force, leading to reversal of phase-segregation. This atomistic understanding can enable some control of the phase-segregation by selecting substituting elements on the B site–such as replacing some Pb by Sn–that are unable to form stable Frenkel defects.},

keywords = {Alloys of halide perovskite, Frenkel pair, Phase segregation},

pubstate = {published},

tppubtype = {article}

}