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

Nickel oxide (NiO x ) 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 NiO x 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 NiO x –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 NiO x surface, which simultaneously enlarges the NiO x 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 NiO x 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 NiO x ‐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 NiO x –perovskite interface for highly efficient blue PeLEDs.