By combining the thermal evaporation and spin-coating techniques, we are able to demonstrate synthesis of 3 cm x 3 cm and 1.5 cm x 1.5 cm organometallic halide perovskite light-emitting diodes with electroluminescence at 538 nm and 405 nm, respectively. Other than the advantage in large device area, to our best knowledge, the demonstrated violet LEDs have produced the shortest emission wavelength available from current hybrid perovskites. The luminance of our green LEDs reach a maximum value of 9967 cd/m2 with an EQE of 0.88% and color purity of 95%. Moreover, it is possible to generate white light emission by combining the violet perovskite LEDs with visible light phosphor.
