Bright and efficient sky-blue perovskite light-emitting diodes via doping of π-conjugated molecule tetraphenylethylene

As a star material, to date, hybrid perovskites with green and red emission show high photoluminescence quantum yields, and the external quantum efficiency (EQE) of perovskite light-emitting diodes (PeLEDs) has exceeded 20%. However, due to the poor film quality and large energy level mismatch, the performance of blue PeLEDs still lags far behind. Herein, a π-conjugated tetraphenylethylene (TPE) doping strategy is demonstrated to improve both the efficiency and stability of sky-blue PeLEDs. With proper TPE doping, the defects are passivated and the energy levels of multi-cation perovskite are elevated, resulting in a smooth and dense film with high PLQY (∼27.8%). The champion PeLED shows a brightness of 12,963 cd/cm² at 484 nm and maximum EQE of 6.97%. Moreover, after TPE doping, the operational stability of the PeLED increases from 290 s to 960 s under continuous working condition. The π-conjugated molecule doping strategy could open up a new avenue for the design of high-performing blue PeLEDs.