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.