Red-Light-Mediated Photocatalytic Hydrogen Evolution by Hole Transfer from Non-Fullerene Acceptor Y6

We report the use of blend nanoparticles (NPs) of the organic semiconductors PM6 and Y6 for the photocatalytic production of hydrogen under sacrificial conditions, with a 2% mass loading of Pt cocatalyst. When prepared using TEBS, a thiophene-containing surfactant, these blend NPs have a desirable intermixed morphology. Under ≈1-sun illumination from 400 to 900 nm, hydrogen is produced at a rate of 8000 ± 400 μmol h–1 g–1. Remarkably, this rate remains high at 5200 ± 300 μmol h–1 g–1 under 650 to 900 nm excitation, where Y6 is exclusively excited, generating free charges by hole transfer from Y6 to PM6. The rate drops to 2400 ± 200 μmol h–1 g–1 under 400 to 600 nm excitation, where PM6 is preferentially excited and free charges are generated through electron transfer. We also show that the external quantum efficiency is wavelength-independent. This work is the first study to show that free charge generation through hole transfer contributes significantly to hydrogen evolution in a donor:acceptor blend.