Linguistics

Acceptor

Philosophy

Photochemistry

Materials science

Atomic physics

Molecule

Quantum yield

Triplet state

Photon upconversion

Physics

Fusion

Organic chemistry

Optics

Doping

Fluorescence

Condensed matter physics

Excited state

Chemistry

Optoelectronics

The Journal of Physical Chemistry Letters

Manipulating triplet states is technically intriguing for organic semiconductors and photochemical conversion. Sensitized photon upconversion that converts low-energy photons into higher-energy ones via triplet fusion holds great potential in augmentation of photovoltaic devices and photocatalysis. Conventional requirement of exothermic triplet-triplet energy transfer in sensitized upconversion constrains the development of upconversion donor-acceptor pairs. We demonstrate an upconversion system by utilizing a triplet energy-deficient donor within a triplet acceptor matrix, in which efficient thermally activated triplet-triplet energy transfer overcoming an energy barrier of up to 180 meV and an over 5% upconversion quantum yield in the solid state are achieved upon 635 nm irradiation at 195 mW/cm2. The effective solid-state upconversion through thermally activated triplet-triplet energy transfer establishes a new pathway to extract triplet energy from low-lying sensitizers, transcending traditional restriction in matching components energy level.

Thermally Activated Delayed Fluorescence via Triplet Fusion