Achievement of persistent and efficient organic room-temperature phosphorescence with temperature-response by adjusting the proportion of excited-state configurations in coupled molecules

Abstract

Organic materials with persistent room-temperature phosphorescence (pRTP) have played an important role in many fields. However, it is difficult to simultaneously improve the efficiency and lifetime of pRTP via the introduction of simple groups. Herein, we synthesized OMe-SPh (τ = 58.1 ms and Φ_P = 4.47%) by introducing a methoxy group into SPh (τ = 43.2 ms and Φ_P = 2.48%). Moreover, further extension of the conjugate chain, i.e. OMe-SPhT, was achieved by dibenzothiophene, and OMe-SPhT possessed both a high efficiency and a long lifetime (τ = 171 ms and Φ_P = 4.71%). In this case, we desired a balance of different excited-state configurations (nπ* and ππ*), which were verified via single-crystal X-ray diffraction analysis and theoretical time-dependent density functional theory calculations. In addition, the pRTP from neighbouring molecules exhibited a higher stability character than the phosphorescence from the traditional single molecule, especially at room temperature. Based on this property, OMe-SPhT achieved the real-time change in phosphorescence color in response to temperature.