State Key Laboratory of Elemento-Organic Chemistry, Frontiers Science Center for New Organic Matter, College of Chemistry, Nankai University, Tianjin, 300071, China.
Research Center for Analytical Sciences and Tianjin Key Laboratory of Biosensing and Molecular Recognition, College of Chemistry, Nankai University, Haihe Laboratory of Sustainable Chemical Transformations, Tianjin, 300192, China.
Angew Chem Int Ed Engl. 2023 Jun 19;62(25):e202303093. doi: 10.1002/anie.202303093. Epub 2023 May 9.
Triplet-triplet annihilation upconversion (TTA-UC) with near-infrared (NIR) photosensitizers is highly desirable for a variety of emerging applications. However, the development of NIR-to-blue TTA-UC with a large anti-Stokes shift is extremely challenging because of the energy loss during the intersystem crossing (ISC). Here, we develop the first NIR-absorbing B,N-heteroarene-based sensitizer (BNS) with multi-resonance thermally activated delayed fluorescence (MR-TADF) characters to achieve efficient NIR-to-blue TTA-UC. The small energy gap between the singlet and triplet excited states (0.14 eV) of BNS suppresses the ISC energy loss, and its long-delayed fluorescence lifetime (115 μs) contributes to efficient triplet energy transfer. As a result, the largest anti-Stokes shift (1.03 eV) among all heavy-atom-free NIR-activatable TTA-UC systems is obtained with a high TTA-UC quantum yield of 2.9 % (upper limit 50 %).
三重态-三重态湮灭上转换（TTA-UC）与近红外（NIR）光敏剂相结合，对于各种新兴应用具有很高的吸引力。然而，由于系间穿越（ISC）过程中的能量损失，开发具有大反斯托克斯位移的近红外到蓝色 TTA-UC 极具挑战性。在这里，我们开发了第一个具有多共振热激活延迟荧光（MR-TADF）特性的 NIR 吸收 B,N-杂芳环基敏化剂（BNS），以实现高效的近红外到蓝色 TTA-UC。BNS 的单重态和三重态激发态之间的小能隙（0.14 eV）抑制了 ISC 能量损失，其长延迟荧光寿命（115 μs）有助于有效的三重态能量转移。因此，在所有无重原子的近红外激活 TTA-UC 体系中获得了最大的反斯托克斯位移（1.03 eV），TTA-UC 量子产率高达 2.9%（上限 50%）。
