Exciton tunability in mixed halide hybrid layered perovskites

Abstract

Two dimensional (2D) metal halide perovskites are being extensively studied as they can serve as promising materials for various optoelectronic devices such as light emitting diodes (LED), lasers, photodetectors etc. The optical properties of these 2D perovskite can be tuned by varying the stoichiometric compositions of metals (Pb, Sn, Ge, Bi) and halides (Cl, Br, I). Here we report, a single step synthesis process for the fabrication of mixed halide based 2D perovskite of type (C4H9NH3)2PbI4(1-y)Br4y (y=0-1). By changing of iodine with bromine in metal halide (Pb-X) network of these mixed halide 2D perovskites, we have achieved well controlled and uniform tunability of intense room temperature exciton absorption peaks from green to UV region (513 nm to 405 nm) of spectra. Highly crystalline and layered structure of the mixed halide 2D perovskite thin films (hereafter PTF) are confirmed by using thin film X-ray diffraction (XRD) studies whereas, Energy dispersive X-ray (EDAX) analysis confirms the uniform distribution of iodine and bromine in the thin films, thus supporting that our demonstrated synthesis route is very useful and easy in producing single phase mixed halide perovskites.