Experimentally Observed Reverse Intersystem Crossing‐Boosted Lasing. (23rd September 2020) - Zhou, Zhonghao
Abstract: Thermally activated delayed‐fluorescent (TADF) materials are anticipated to overcome triplet‐related losses towards electrically driven organic lasers. Thus far, contributions from triplets to lasing have not yet been experimentally demonstrated owing to the limited knowledge about the excited‐state processes. Herein, we experimentally achieve reverse intersystem crossing (RISC)‐boosted lasing in organic microspheres with uniformly dispersed TADF emitters. In these materials, triplets are continuously converted to radiative singlets through RISC, giving rise to reduced losses in stimulated emission. The involvement of regenerated singlets in population inversion results in a thermally activated lasing; that is, the lasing intensity increases with increasing temperature, accompanied by accelerated depletion of the excited‐state population. Benefiting from the suppression of triplet accumulations by RISC processes, a high‐repetition‐rate microlaser was achieved. Abstract : Reverse intersystem crossing‐boosted lasing was experimentally demonstrated in self‐assembled microspheres with uniformly dispersed organic thermally activated delayed‐fluorescence molecules. The lasing intensity increases with increasing temperature due to the involvement of regenerated singlets in population inversion, which provides a way to overcome triplet‐related losses for high‐performance organic lasers.