Short-range charge transfer for efficient ultra-narrowband deep blue afterglow

Abstract

Abstract Efficient and narrowband blue organic afterglow materials are critical components for advanced optoelectronic applications, but so far, have been rarely explored. Herein, we report short-range charge transfer-assisted high efficiency and ultra-narrowband deep blue (<450 nm) afterglow from a series of indolocarbazole-based chromophores. The short-range charge transfer within the fused π-conjugated frameworks enlarges the singlet-triplet energy gap and suppresses vibronic coupling and structural relaxations, thus leading to a slow reverse intersystem crossing rate, a long delayed-fluorescence lifetime of up to 186.48 ms and a high photoluminescence quantum yield of 86.1%. Notably, these afterglow emitters exhibit ultra-narrow full width at half maximum of 18 nm, presenting high colour purity with y colour coordinates below 0.05. Taking advantage of these unique afterglow features, the potential for encrypted light communications and high-resolution afterglow displays are demonstrated. This work not only provides an effective strategy for developing narrowband organic afterglow materials but also extends their applications to advanced fields.