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Intrinsic doping limit and defect-assisted luminescence in Cs4PbBr6

revised on 24.04.2019, 02:22 and posted on 24.04.2019, 20:21 by Young-Kwang Jung, Joaquin Calbo, Ji-Sang Park, Lucy D. Whalley, Sunghyun Kim, Aron Walsh
Cs4PbBr6 is a member of the halide perovskite family that is built from isolated (zero-dimensional) PbBr64- octahedra with Cs+ counter ions. The material exhibits anomalous optoelectronic properties: optical absorption and weak emission in the deep ultraviolet (310 - 375 nm) with efficient luminescence in the green region (~ 540 nm). Several hypotheses have been proposed to explain the giant Stokes shift including: (i) phase impurities; (ii) self-trapped exciton; (iii) defect emission. We explore, using first-principles theory and self-consistent Fermi level analysis, the unusual defect chemistry and physics of Cs4PbBr6. We find a heavily compensated system where the room-temperature carrier concentrations (< 109 cm-3) are more than one million times lower than the defect concentrations. We show that the low-energy Br-on-Cs antisite results in the formation of a polybromide (Br3) species that can exist in a range of charge states. We further demonstrate from excited-state calculations that tribromide moieties are photoresponsive and can contribute to the observed green luminescence. Photoactivity of polyhalide molecules is expected to be present in other halide perovskite-related compounds where they can influence light absorption and emission.


Email Address of Submitting Author


Yonsei University



ORCID For Submitting Author


Declaration of Conflict of Interest

No conflict of interest.


Read the published paper

in Journal of Materials Chemistry A