Triplet-Triplet Annihilation Photon Upconversion Using TIPS-Benzene and Heptazine Derivatives for UVC Energy Generation

21 April 2025, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

UV energy generation via triplet-triplet annihilation-based photon upconversion (TTA-UC) plays a pivotal role in enabling high-energy photochemical reactions. However, generating UVB/UVC energy through TTA-UC remains a significant challenge. In this work, the TTA-UC from visible/UVA to UVB/UVC is demonstrated by combining (triisopropylsilyl)ethynyl benzene (TIPS-benzene)-based emitters with an organic sensitizer, a heptazine derivative. The heptazine derivative exhibits absorption in visible/UVA region and has a triplet energy level high enough to sensitize the TIPS-benzene-based emitters. The introduction of bulky substituents into TIPS-benzene suppresses the deactivation pathways of the excited triplet state that compete with TTA, thereby enhancing the TTA-UC efficiency. This study demonstrates the direction of molecular design for the challenging generation of UVB/UVC energy.

Keywords

photon upconversion
triplet-triplet annihilation
UVC energy
TIPS-benzene
heptazine

Supplementary materials

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Description
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Supporting Information
Description
Experimental details, material characterizations, absorption/photoluminescence spectra, photoluminescence decays, calculated energy levels, upconversion luminescence stalibity
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