Tailoring Niox/Perovskite Interface via a Multifunctional Self‐Assembled Molecule for High‐Performance Blue Perovskite Light‐Emitting Diodes

Nickel oxide (NiOx) serves as one of the most promising hole transport materials for perovskite light‐emitting diodes (PeLEDs). However, only moderate PeLED performances have been reported on the pristine NiOx layer due to insufficient hole injection, interfacial exciton quenching, and poor perovskite quality. Herein, a multifunctional molecule of 3‐mercapto‐1‐propanesulfonate (MPS) is demonstrated to successfully tailor the NiOx–perovskite heterogenous interface by addressing the above issues. In detail, the large binding energy between mercapto sulfur and nickel induces preferential self‐assembly of the mercapto group on the NiOx surface, which simultaneously enlarges the NiOx work function by the formation of interfacial dipole and suppresses the trap‐assisted exciton quenching by the passivation of the oxygen vacancies. Meanwhile, the self‐assembled MPS on NiOx also favors high‐quality perovskite films with good morphology, high crystallinity, and reduced defects for efficient carrier radiative recombination. As a result, blue PeLEDs show a remarkable efficiency of 10.4%, representing one of the highest efficiencies for NiOx‐based blue PeLEDs, as well as a very low turn‐on voltage of 2.8 V. Consequently, this work contributes to an efficient approach to tailor the NiOx–perovskite interface for highly efficient blue PeLEDs.