Recently, some progress in this area has been made. Wei et al. reported two new multiresonance TADF sensitizers which when paired with TIPS-Naph or a derivative thereof afforded green-to-UV TTA-UC for the first time. While a relatively modest FUC value of 3.8% is reported, they managed to reach a low Ith of 9.2 mW cm -2 . Part of the success is ascribed to the high molar extinction that was determined for these sensitizers (e >10 5 M -1 cm -1 ), enabled by limiting their structural flexibility and by including electron-deficient boron covalently bonded to the donor units.