Red-to-blue photon up-conversion with high efficiency based on a TADF fluorescein derivative†
Abstract
A new photon up-conversion system with a TADF fluorescein derivative as a photosensitizer was developed to achieve a quite large anti-Stokes shift from red to blue with a fairly high up-conversion emission quantum yield. This TADF photosensitizer has a very small ΔEST to provide a 207 nm anti-Stokes shift photon up-conversion. Meanwhile, it has a quite long triplet state lifetime (22.11 μs) and a large molar extinction coefficient to assure a high up-conversion efficiency of 11.2%. These results fully demonstrated the potential of the TADF fluorescein derivative as the photosensitizer used in photon up-conversion for the first time.