Li Lemin, Kamal Saeid, Polgar Alexander M, Hudson Zachary M
Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada.
J Phys Chem B. 2024 Sep 19;128(37):8997-9004. doi: 10.1021/acs.jpcb.4c02774. Epub 2024 Sep 4.
Molecules capable of thermally activated delayed fluorescence (TADF) can exhibit triplet lifetimes on the order of μs-ms as well as low energy losses in the intersystem crossing (ISC) process. As a result, they have great potential to be used as sensitizers in triplet-triplet annihilation upconversion (TTA-UC) systems with high anti-Stokes shifts, replacing traditional phosphorescent sensitizers. In this study, we employ a red-absorbing boron difluoride curcuminoid-based TADF molecule as the sensitizer and a 9,10-diphenylanthracene derivative as the annihilator. We polymerize them to synthesize a polymer-based red-to-blue TTA-UC system with an anti-Stokes shift of up to 182 nm (0.9 eV) and an upconversion photoluminescence quantum yield (PLQY) of 0.77%. To our knowledge, this is the first report of a TTA-UC polymer containing a TADF photosensitizer. The upconversion properties were investigated through power-dependent experiments and photoluminescence decay measurements. This work provides a more detailed understanding of TTA-UC polymers, highlights the strength of TADF sensitizers in improving anti-Stokes shifts in TTA-UC systems, and demonstrates the feasibility of building polymer-based upconversion systems. This development will expand the application of purely organic TTA-UC.
能够产生热活化延迟荧光（TADF）的分子在μs-ms量级的三重态寿命以及系间窜越（ISC）过程中的低能量损失方面表现出色。因此，它们在具有高反斯托克斯位移的三重态-三重态湮灭上转换（TTA-UC）系统中作为敏化剂具有巨大潜力，有望取代传统的磷光敏化剂。在本研究中，我们采用一种吸收红光的基于二氟化硼姜黄素类的TADF分子作为敏化剂，以及一种9,10-二苯基蒽衍生物作为湮灭剂。我们将它们聚合以合成一种基于聚合物的红到蓝TTA-UC系统，其反斯托克斯位移高达182 nm（0.9 eV），上转换光致发光量子产率（PLQY）为0.77%。据我们所知，这是关于含有TADF光敏剂的TTA-UC聚合物的首次报道。通过功率相关实验和光致发光衰减测量对上转换特性进行了研究。这项工作为TTA-UC聚合物提供了更详细的理解，突出了TADF敏化剂在改善TTA-UC系统中反斯托克斯位移方面的优势，并证明了构建基于聚合物的上转换系统的可行性。这一进展将扩大纯有机TTA-UC的应用。
