Dual‐Function Self‐Assembled Molecules as Hole‐Transport Layers for Thermally Evaporated High‐Efficiency Blue Perovskite Light‐Emitting Diodes

Thermally evaporated perovskite light-emitting diodes (PeLEDs) hold immense potential for future applications in the display industry. However, the performance of blue PeLEDs is far behind, one of the most important reasons is the lack of suitable hole-transporting materials. Herein, the study designs and synthesizes a new class of self-assembled monolayer (SAM) materials, namely, (2-(3,6-bis(4-formylphenyl)-9H-carbazol-9-yl)ethyl)phosphonic acid (C-2PACz) and (2-(3,6-bis(4-(methylsulfonyl)phenyl)-9H-carbazol-9-yl)ethyl)phosphonic acid (S-2PACz). First, the phosphonic acid is induced to form bidentate bonds with ITO. Second, the strong electron-withdrawing groups are integrated to increase the electron cloud density of the termini contacting with perovskite, which enhances the electrostatic interaction with the Pb