Singlet-to-Triplet Absorption for Near-Infrared-to-Visible Photon Upconversion

Abstract

This review highlights the advancement of molecular triplet donors showing singlet-to-triplet (ST) absorption and their utilization for triplet-triplet annihilation-based photon upconversion (TTA-UC). Circumvention of thermal energy loss associated with intersystem crossing (ISC) through the use of ST absorption results in UC from near-infrared (NIR) light to yellow, blue, and even violet light, achieving an unprecedentedly large UC spectral shift. Taking advantage of the molecular donor's ability to be dispersed in solids without aggregation, efficient solid-state UC materials are also achieved.