Revisiting the origin of green emission in Cs4PbBr6

Abstract

It is probably acceptable to state that the recent debate over the origin of green emission in Cs₄PbBr₆ and/or CsPbBr₃ has been narrowed down to two major possibilities: (i) a defect-mediated event in Cs₄PbBr₆, or (ii) a radiative recombination of charge carriers at CsPbBr₃ inclusions embedded within Cs₄PbBr₆. The first scenario is relatively broad in terms of identifying specific defects that could act as recombination centers, although Br-vacancy has been proposed as a potential candidate. In the case of the second possibility, the omnipresence of CsPbBr₃ nanoinclusions even in pure phase Cs₄PbBr₆ is also a matter of contention. Resolving this “green emission question” is consequential to the further development of the Cs–Pb–X (X = halogen) system of perovskite-inspired optoelectronic materials. Here, we will briefly survey the current status of the literature and offer some perspectives with respect to the two possibilities noted above.