Fast Intrinsic Emission Quenching in Cs4PbBr6 Nanocrystals

Cs4PbBr6 (0D) nanocrystals at room temperature have both been reported as nonemissive and green-emissive systems in conflicting reports, with no consensus regarding both the origin of the green emission and the emission quenching mechanism. Here, via ab initio molecular dynamics (AIMD) simulations and temperature-dependent photoluminescence (PL) spectroscopy, we show that the PL in these 0D metal halides is thermally quenched well below 300 K via strong electron-phonon coupling. To unravel the source of green emission reported for bulk 0D systems, we further study two previously suggested candidate green emitters: (i) a Br vacancy, which we demonstrate to present a strong thermal emission quenching at room temperature; (ii) an impurity, based on octahedral connectivity, that succeeds in suppressing nonradiative quenching via a reduced electron-phonon coupling in the corner-shared lead bromide octahedral network. These findings contribute to unveiling the mechanism behind the temperature-dependent PL in lead halide materials of different dimensionality.

Automated summary

Through simulations and experiments, it has been shown that the photoluminescence of Cs4PbBr6 nanocrystals at room temperature is thermally quenched due to strong electron-phonon coupling, shedding light on the controversy surrounding the green emission; investigations indicate that Br vacancies and specific impurities are the main factors contributing to the green emission.