Multiple σ–π Conjugated Molecules with Selectively Enhanced Electrical Performance for Efficient Solution‐Processed Blue Electrophosphorescence

Abstract Selectively and controllably regulating molecular functions of organic optoelectronic materials with high solubility for solution‐processible devices is highly desired but remains as one of the most significant challenges in material science. Here, a concise molecular design strategy is reported to achieve effective electronic communications using efficient d‐orbital participated σ–π conjugations between Si and π unit for purposely modulating the electrical properties of organic optoelectronic materials. Through a two‐step reaction in high yield, DSiDCzSi with the enhanced σ–π conjugation is facilely constructed by introducing multiple triphenylsilanes into carbazole unit. Impressively, DSiDCzSi demonstrates a largely increased d‐orbital participated extent of Si, which results in the selectively improved frontier orbital energy level, enhanced carrier injection and transportation ability, excellent solubility, and film‐forming property. Using DSiDCzSi as a host matrix, solution‐processed blue electrophosphorescence device exhibits a maximum external quantum efficiency up to 23.5%, which is among the best values of FIr6‐based blue phosphorescent organic light‐emitting diodes reported to date. This work, which reveals the vital role of d‐orbital participated σ–π conjugations in solving the inherent interference between optical and electrical properties of π‐conjugated materials, can provide an extensible and universal avenue for designing and constructing high‐performance organic optoelectronic materials for advanced device applications.