Ligand Triplet Energy Transfer from Perylene Diimide Derivatives to PbS Quantum Dots in Solution

Abstract

A novel strategy has been devised to regulate the rate of triplet energy transfer by manipulating the energy level difference between the organic singlet fission donors and inorganic acceptors. The triplet energy donor PBI-OMe and acceptor PbS quantum dots are interconnected through carboxyl groups, resulting in varying degrees of orbital coupling between quantum dots of different energy levels and the donor. This is achieved through energy level diagrams and triplet energy transfer rates. The TET rate constants of PBI-OMe 0.91, PBI-OMe 1.29, and PBI-OMe 1.45 with different band gaps calculated are 2.63 × 10⁹, 6.59 × 10⁹, and 7.97 × 10⁹ s^–1 by time-resolved absorption spectroscopy, respectively. We confirmed that the TET rate from PBI-OMe to PbS QDs is limited by the degree of orbital coupling between PBI-OMe and PbS QDs, and that within a certain band gap range, samples with higher band gaps have better orbital coupling and achieve faster TET rates. Our work provides a straightforward and controllable platform to investigate the interfacial energy transfer process between SF materials and inorganic semiconductors, offering a new way to design molecule–nanocrystal combinations with high photovoltaic conversion efficiency and potential applications in other optoelectronic fields.