Based on the reduction potential of diethyl maleate (Ered = -1.43 V vs SCE in DMF, Figure ), oxidative quenching of pDTCz-DPmS (E !" * = -1.44 V vs SCE in DCM) by diethyl maleate is thermodynamically feasible, while this is not the case for 4CzIPN (E !" * = -1.09 V vs SCE in DCM). To ensure the quenching of pDTCz-DPmS by diethyl maleate was occurring through SET, and not by energy transfer via a Z à E isomerisation process, the irradiation of diethyl maleate in the presence of pDTCz-DPmS was conducted. As expected from the reported triplet energies of the maleate and fumarate isomers (ET = 3.08 eV and 2.87 eV, respectively), 2 pDTCz-DPmS (ET = 2.97 in DMF) could not isomerize diethyl maleate (see SI for more details), therefore we can confidently conclude that this quenching process proceeds via SET.