Modulating Room Temperature Phosphorescence by Oxidation of Thianthrene to Achieve Pure Organic Single-Molecule White-Light Emission

In order to develop pure organic single-molecule white-light emitters (SMWLE), the oxidation of thianthrene (TA) was performed on sulfur atoms at different degrees to tune room temperature phosphorescence (RTP) emission. With increasing degrees of oxidation from 1OTA, 2OTA, 3OTA, to 4OTA, monomeric and aggregative RTP emission was gradually suppressed, due to the gradual disappearance of lone pair electrons on sulfur atoms. Among these compounds, monomers and aggregates of 1OTA demonstrated a better intensity match between fluorescence and RTP. Through partial oxidation of TA, 1OTA exhibited the simultaneous ternary emissions from the lowest singlet state (S-1), the lowest triplet state (T-1), and the high-lying triplet state (T-n) in doped film. The single-molecule white-light emission was achieved in 1OTA crystal with a photoluminescence quantum yield (PLQY) of 47.1%. This work not only reports the RTP behavior of TA with different degrees of oxidation, but also provides an example of excited-state modulation to harvest an efficient SMWLE material.

Automated summary

By oxidizing thianthrene at different degrees, a pure organic single-molecule white-light emitter was developed, demonstrating the modulation effect of oxidation levels on room temperature phosphorescence emission.