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.