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Li, Lemin

University of British Columbia

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 polymerized them to synthesize a polymer-based red-to-blue TTA-UC system with an anti-Stokes shift up to 182 nm (0.9 eV) and a normalized upconversion efficiency of 0.77%. To our knowledge, this is the first report of a TTA-UC polymer containing a TADF photosensitizer. Small molecule analogues of the polymer system were also prepared for comparison. The upconversion properties were investigated and the energy transfer process between sensitizers and annihilators was studied. 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.

Text

2024-09-05

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/89178

Chemistry

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/