Riboflavin – understanding the dynamics and interactions of the triplet state

O. We also report pronounced delayed fluorescence (DF) of riboflavin in air-saturated samples, attributed to the singlet oxygen feedback mechanism. Finally, we discuss how the DF signal can be used to reveal energy transfer efficiency to other sensitisers, such as aluminium phthalocyanine, where we demonstrate a dominant role of the triplet-triplet transfer mechanism.