Design of perovskite light-emitting diodes based on FAPbBr3 nanocrystals synthesized by ultrasonic crushing method

Perovskite light-emitting materials possess advantages of high photoluminescence quantum yield (PLQY) and charge carrier mobility, large carrier diffusion length, narrow emission spectrum, easily tunable bandgap, and low preparation costs, leading to the great research enthusiasm in the last decade. However, the research progress of blue perovskite light-emitting diode (LED) is slow, because the synthesis of blue perovskite material is difficult and it is unstable in the air. In this work, blue and green perovskite quantum dots (PQDs) can be obtained by adjusting the growth temperature and ultrasonic time. Photoluminescence (PL) measurements suggest that the luminescence wavelength of PQDs decreases significantly from 528nm to 468nm with increasing the ultrasound time from 4 to 30 min and decreasing the temperature from 2 to -10℃. The reduction of grain size investigated by transmission electron microscopy (TEM) is responsible for the blue-shift of luminous peaks. The perovskite light-emitting diodes (PeLEDs) based on the as-prepared green and blue PQDs have been fabricated. The best performing PeLEDs devices for green and blue light emission showed the maximum external quantum efficiency (EQE) of 6.179% and 0.45%, respectively. This work provides an effective method for the preparation of blue-green PQDs and PeLEDs.