Crown-Assisted CsCu₂I₃ Growth and Trap Passivation for Perovskite Light-Emitting Diodes

Copper (Cu)-based perovskites are promising for lead-free perovskite light-emitting diodes (PeLEDs). However, it remains a significant challenge to achieve high performance devices due to the nonradiative loss caused by the disordered crystallization and lack of passivation. Crown ethers are known to form host–guest complexes by the interaction between C–O–C groups and certain cations, and 18-crown-6 (18C6) with an appropriate complementary size can interact with Cs + and Cu + cations. Herein, we studied the interaction between CsCu 2 I 3 and two crowns with the same cyclic size, 18C6 and dibenzo-18-crown-6 (D18C6). Particularly, D18C6 can reduce the nonradiative recombination rate of CsCu 2 I 3 film by passivating the defects and optimizing the film morphology effectively. The room mean square (RMS) decreased from 5.06 to 2.95 nm, and the PLQY was promoted from 4.71% to 19.9%. Besides, D18C6 can also decrease the barrier of hole injection. The PeLEDs based on D18C6-modified CsCu 2 I 3 realized noticeable improvement with a maximum luminance and EQE of 583 cd/m 2 and 0.662%, respectively.