Green Emission Induced by Intrinsic Defects in All-Inorganic Perovskite CsPb₂Br₅

All-inorganic perovskites with improved stability are expected to be better candidates for optoelectronics, compared to organic-inorganic hybrid perovskites. A new member of all-inorganic perovskites, CsPb₂Br₅, has attracted great attention for its promising applications in optoelectronic devices. However, the origins of the green emission in CsPb₂Br₅ have been actively debated. By using first-principles calculations, we find that Cs_Pb and V_Br are dominant intrinsic defects independent of the growth conditions within the stable region of CsPb₂Br₅. Interestingly, we suggest that individual intrinsic defects do not lead to the green emission of CsPb₂Br₅, while the donor-acceptor pair recombination of Cs_Pb and V_Br possibly does. Our findings provide new insights into the experimental controversy about the green emission and its origins in CsPb₂Br₅ from the perspective of intrinsic defects, which help to extend the application of CsPb₂Br₅ in optoelectronic devices.