Efficient Utilization of Solar Energy Mediated by Singlet Fission Passage to Boost Photocatalytic Hydrogen Production

Building efficient channels for capturing and utilizing light energy is the key to achieving sustainable utilization of solar energy, so as to enhance the photocatalytic activity. However, one of the biggest challenges at present is that when a material absorbs a photon, it only generates a pair of electron-holes, with excess energy heating loss. The singlet fission (SF) process could achieve the effect of exciton multiplication to break this limitation. Based on this, a heterojunction structure was constructed consisting of polythiophene-derived carbon dots (CDs) and a carboxyl-functionalized fullerene derivative, tetra[4-(carboxyl) piperidin-1-yl]C₆₀ epoxide (TCPC). The intrinsic SF activity of the CDs was experimentally confirmed, demonstrating a remarkably high triplet quantum yield of 191%. Crucially, integration with TCPC facilitates the efficient dissociation of triplet excitons into long-lived charge carriers with lifetimes exceeding 100 µs. Then the photogenerated carriers are efficiently utilized by the catalytic center and enables an apparent quantum yield of 27.4% at 420 nm and a hydrogen evolution rate of 116.97 mmol·g^-1·h^-1. This creates a brand-new channel for enhancing the efficiency of solar energy conversion. It not only broadens the application scope of SF-active materials but also provides an exceptional strategy for achieving sustainable and high-efficiency solar-to-hydrogen conversion.