# Doublet-triplet energy transfer dominated photon upconversion

## TL;DR

This paper reports a novel pi-radical dye that enables efficient triplet energy transfer for photon upconversion, offering new insights into designing triplet sensitizers for advanced luminescent materials.

## Contribution

Demonstrates a new pi-radical dye capable of Dexter-like doublet-triplet energy transfer to facilitate photon upconversion.

## Key findings

- The pi-radical dye exhibits remarkable doublet emission.
- The dye can initiate triplet-triplet annihilation photon upconversion.
- The process enables converting red light to cyan or green light.

## Abstract

Stable luminescent pi-radicals with doublet emission have aroused a growing interest for functional molecular materials. We have demonstrated a neutral pi-radical dye (4-N-carbazolyl-2,6-dichlorophenyl)bis(2,4,6-trichlorophenyl)-methyl (TTM-1Cz) with remarkable doublet emission, which could be used as triplet sensitizer to initiate the photophysical process of triplet-triplet annihilation photon upconversion (TTA-UC). Dexter-like excited doublet-triplet energy transfer (DTET) was confirmed by theoretical calculation. A mixed solution of TTM-1Cz and aromatic emitters could ambidextrous upconvert red light to cyan light or green light = 532 nm) to blue light. This finding of DTET phenomena provides a new perspective in designing new triplet sensitizer for TTA-UC.

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Source: https://tomesphere.com/paper/1701.03894