Selenium-containing amino acid passivated deep-red perovskite quantum dot light-emitting diodes

Perovskite quantum dot (QD) light-emitting diodes (LEDs) typically exhibit a trade-off between emission efficiency and spectral stability. This compromise primarily arises from nonradiative recombination losses attributed to Pb²+ defects, halide phase segregation, and self-doping effects. In this study, we employ an environmentally friendly ligand exchange strategy utilizing short-chain selenium-containing L-seleno-methylselenocysteine (L-SeMSC) to passivate defects in perovskite QDs and replace the high-resistive long-chain ligands of oleate and oleylammonium. Theoretical and experimental findings indicate that the oxygen lone pair electrons from the carboxyl group in L-SeMSC effectively coordinate with Pb²+ defects on the surface of CsPb(Br/I)3 QDs, while the positively charged amino group inhibits halide ion migration. This coordination significantly enhances the photoluminescence quantum yield, thermal and air stability, and electroluminescence performance. The optimal LED achieves a maximum brightness of 2222.4 cd m−2 and an external quantum efficiency (EQE) of 17.18% at 654 nm, surpassing the performance of the control device, which exhibits a maximum brightness of 524.2 cd m−2 and an EQE of 8.94%, characterized by unstable luminescence emission. This study underscores the critical role of selenium-containing amino acids in enhancing the performance and stability of perovskite QD LEDs.