Enhancing photon upconversion with thermally activated sensitization and singlet energy collection

Abstract

Photon upconversion microcrystals based on triplet–triplet annihilation (TTA) were developed involving thermally activated energy transfer and a singlet energy collection mechanism. Efficient solid-state upconversion with an apparent anti-Stokes shift of 0.8 eV was achieved and the upconversion quantum yield was increased by 40% by the singlet energy collector, which inhibited the FRET-type back energy transfer from the upconverted annihilator to the sensitizer. The improvement in the upconversion microcrystals practically benefited the upconversion-driven photoproduction of hydrogen, demonstrating the potential of solid-state TTA upconversion materials in optoelectronics and photocatalysis.