Direct observation of the intermolecular triplet-triplet energy transfer from UV-A absorber 4-tert-butyl-4′-methoxydibenzoylmethane to UV-B absorber octyl methoxycinnamate

► The EPR Bmin signal of OMC was observed through the selective excitation of BM-DBM. ► The phosphorescence of OMC was observed through the selective excitation of BM-DBM. ► A conclusive proof of the intermolecular TET from BM-DBM to OMC was demonstrated. ► This is the first experimental evidence of the TET between organic UV absorbers.