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.

Currently the area of perovskite LED components is still limited to a few mm square. Our team breaks this barrier by combine solution process with thermal evaporation to produce a large-area component with a size of 3 cm x 3 cm. The quality of the as-prepared perovskite film was carefully examined with various characterization techniques. In this work, parameters of the original device structure were modified, such as uniformity of the active layer, thickness of the electron injection layer, electron transport layer, and Ag cathode electrode to improve uniform injection of electrons. Area of the fabricated LEDs was significantly increased from the original 0.09 cm2 to 9 cm2. We also demonstrated a first violet perovskite LED  with electroluminescence at 405 nm.

Our perovskite LED manufacturing process is simple, less time-consuming and cost-effective. The demonstrated devices are large in area but very lightweight due to a thickness of only a few mm. A large number of perovskite LEDs can be made in a short period of time, which is favorable for mass production.  Apart from the aforementioned advantages, these perovskite LEDs are uniformity in morphology with high color purity. Therefore, it can be used as a backlight for liquid crystal displays, or can be applied in monitors, TVs, automobiles, smart wearable devices, biomedical sensors, etc. Moreover, the violet LEDs can combined with visible light phosphors to generate white light emission for lighting purpose.

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