Efficient blue emission from stable silver-based metal halide single crystals

In this paper, the one-dimensional Cs2AgI3 and Cu+-doped Cs2AgI3 single crystals had been synthesized by antisolvent infiltration method. A blue-emission with peak at 473 nm and a large Stokes shift was observed in the Cs2AgI3 single crystals, which might originate from the self-trapped excitons (STEs). Experimental studies revealed that appropriate Cu+ dopant greatly enhanced the Cs2AgI3 photoluminescence quantum yield (PLQY). Theoretical calculation confirmed that the optimized Cu+ concentration could effectively modulate the electronic band structure, and the electronic states highlighted in CuI4 tetrahedron showed strong localized characteristic, which was beneficial to improve the luminescence efficiency of the blue band. In addition, this kind of metal halides exhibited strong stability in air ambient. This work supplies a feasible strategy to improve the optoelectronic performance by extrinsic chemical doping and could prompt the commercial application of lead-free metal halides.