Blue-green color tunable solution processable organolead chloride-bromide mixed halide perovskites for optoelectronic applications

Solution-processed organo-lead halide perovskites are produced with sharp, color-pure electroluminescence that can be tuned from blue to green region of visible spectrum (425-570 nm). This was accomplished by controlling the halide composition of CH₃NH₃Pb(Br_xCl_1-x)₃ [0 ≥ x ≥ 1] perovskites. The bandgap and lattice parameters change monotonically with composition. The films possess remarkably sharp band edges and a clean bandgap, with a single optically active phase. These chloride-bromide perovskites can potentially be used in optoelectronic devices like solar cells and light emitting diodes (LEDs). Here we demonstrate high color-purity, tunable LEDs with narrow emission full width at half maxima (FWHM) and low turn on voltages using thin-films of these perovskite materials, including a blue CH₃NH₃PbCl₃ perovskite LED with a narrow emission FWHM of 5 nm.