Iodine doping of CsPbBr3: toward highly stable and clean perovskite single crystals for optoelectronic applications

Caesium-based mixed halide perovskite single crystals, CsPbBr3-xIx, are shown to be good candidates for many optoelectronic applications under ambient conditions. The partial substitution of iodine into the bromine sites of CsPbBr3 single crystal makes attractive effects in optical and structural properties as well as their thermal and phase stability. Herein, the Inverse Temperature Crystallization (ITC) method has been utilised to grow high-quality, large, and single-phase single crystals of CsPbBr2.4I0.6 perovskites. The iodine doping is found to result in improved purity, thermal, phase, and atmospheric stability of the single crystal and helped to tune the band gap. Further, there is a conspicuous decrease in the defect density with iodine doping. Thus the present study establishes iodine doping as a facile route to grow CsPbBr3 single crystals with overall stability and improved defect density with a broad absorption spectrum, that point toward extended optoelectronic and photovoltaic applications.