Regulating excited state of sulfone-locked triphenylamine heteroaromatics for high-efficiency ultralong room-temperature phosphorescence

Organic room-temperature phosphorescence (RTP) with ultralong lifetime and high quantum efficiency is of interest but challenging. Few phosphor systems in the monomer state demonstrate lifetimes over 0.1 s with quantum efficiencies exceeding 10% due to the lack of molecular design principle and qualified molecular system. Here we present a novel class of phosphors based on heteroaromatic sulfone-locked triphenylamine core BTPO with rational subunit modification that displays ultralong RTP in a doped polymer matrix with lifetimes up to 818 ms and quantum efficiencies over 20% simultaneously. The co-win situation is attributed to an efficient and multichannel intersystem crossing (ISC) process arising from narrower singlet-triplet exchange energy and strong spin-orbital coupling interaction between the lowest singlet state (S1) and high-lying triplet states that facilitate numerous triplet excitons generation, as well as a relatively pure (pi, pi*) configuration for the lowest triplet state (T1), ensuring the small radiative rate of phosphorescence (kp) and consequently ultralong lifetime. Taking advantage of RTP features with the multicolor and diverse lifetime of this phosphor family, the primary application in information encryption is well demonstrated versatilely.