Thermally activated delayed fluorescence (TADF) dyes as efficient organic photosensitizers for photocatalytic water reduction

An efficient water reduction system was developed using thermally activated delayed fluorescence (TADF) dyes as organic photosensitizers and a palladium complex as water reduction catalyst. 2,4,5,6-tetrakis(carbazol-9-yl)-1,3-dicyanobenzene (4CzIPN) that has the best fluorescence efficiency displayed the highest photoinduced productivity (TON up to 2567) and was active for 5 days. Based on time-resolved photoluminescence experiments on the photocatalytic system, reductive quenching of the TADF dye was found as main pathway occurring before intersystem crossing takes place.