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

Abstract

• Organic RTP of ultralong lifetime and high quantum efficiency was presented. • Phosphorescence mechanism based on the excited states regualtion was proposed. • Multilevel information encryption based on liftetimes and colors was shown. 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 (S 1 ) and high-lying triplet states that facilitate numerous triplet excitons generation, as well as a relatively pure (π, π*) configuration for the lowest triplet state (T 1 ), ensuring the small radiative rate of phosphorescence ( k p ) 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.