Molecular Steric Engineering of Ir(III) Complexes Enables Color‐Pure and Efficient NonDoped Deep‐Blue Organic Light‐Emitting Diodes

Nondoped deep‐blue phosphorescent organic light‐emitting diodes (OLEDs) offer simplified architectures and high potential, but are limited by quenching from strong intermolecular interactions. Here, a sterically engineered asymmetric Ir(III) complex, CF ₃ pbib‐Ir, featuring bulky tridentate and CF ₃ ‐substituted ligands that adopt a distorted octahedral geometry to effectively suppress aggregation‐caused quenching and enable stable, efficient deep‐blue emission, is reported. The CF ₃ pbib‐Ir exhibits a sharp emission peak at 431 nm and an ultrashort excited‐state lifetime of 0.34 μs in neat film, significantly shorter than the 0.66 μs in 10% doped films. Correspondingly, the complex achieves a high radiative decay rate of 1.15 × 10 ⁶ s ⁻¹ , indicative of accelerated exciton recombination and reduced nonradiative losses—an essential advantage for OLED architectures, where exciton quenching due to emitter–emitter interactions is significantly suppressed. The nondoped OLED devices incorporating 7 nm CF ₃ pbib‐Ir layer deliver outstanding electroluminescent performance, with deep‐blue Commission International del'Eclairage coordinates of (0.154, 0.070), a low turn‐on voltage of 3.09 V, and a maximum external quantum efficiency of 18.3%. This work establishes a generalizable strategy that leverages steric molecular engineering to overcome the longstanding challenges in nondoped deep‐blue OLEDs. The combination of aggregation suppression, fast radiative decay, and structural versatility enables scalable, color‐pure, and high‐efficiency device platforms, paving the way for next‐generation displays.