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Role of Electron–Phonon Coupling in the Thermal Evolution of Bulk Rashba-Like Spin-Split Lead Halide Perovskites Exhibiting Dual-Band Photoluminescence
journal contribution
posted on 2019-08-23, 14:44 authored by Julian A. Steele, Pascal Puech, Bartomeu Monserrat, Bo Wu, Ruo Xi Yang, Thomas Kirchartz, Haifeng Yuan, Guillaume Fleury, David Giovanni, Eduard Fron, Masoumeh Keshavarz, Elke Debroye, Guofu Zhou, Tze Chien Sum, Aron Walsh, Johan Hofkens, Maarten B. J. RoeffaersThe
optoelectronic properties of lead halide perovskites strongly
depend on their underlying crystal symmetries and dynamics, sometimes
exhibiting a dual photoluminescence (PL) emission via Rashba-like
effects. Here we exploit spin- and temperature-dependent PL to study
single-crystal APbBr3 (A = Cs and methylammonium; CH3NH3) and evaluate the peak energy, intensity, and
line width evolutions of their dual emission. Both perovskites exhibit
temperature trends governed by two temperature regimesabove
and below approximately 100 Kwhich impose different carrier
scattering and radiative recombination dynamics. With increasing temperature,
high-energy optical phonons activate near 100 K to drive energy splitting
of the dual bands and induce line width broadening via electron–phonon
coupling, with a stronger coupling constant inferred for carriers
recombining by the spin-split indirect bands, compared to the direct
ones. We find that the unusual thermal evolutions of all-inorganic
and hybrid bulk lead bromide perovskites are comparable, suggesting
A-site independence and the dominance of dynamic effects, and are
best understood within a framework that accounts for Rashba-like effects.