Ligand Triplet\nEnergy Transfer from Perylene Diimide\nDerivatives to PbS Quantum Dots in Solution

A novel strategy has been devised\nto regulate the rate of triplet\nenergy transfer by manipulating the energy level difference between\nthe organic singlet fission donors and inorganic acceptors. The triplet\nenergy donor PBI-OMe and acceptor PbS quantum dots are interconnected\nthrough carboxyl groups, resulting in varying degrees of orbital coupling\nbetween quantum dots of different energy levels and the donor. This\nis achieved through energy level diagrams and triplet energy transfer\nrates. The TET rate constants of PBI-OMe 0.91, PBI-OMe 1.29, and PBI-OMe\n1.45 with different band gaps calculated are 2.63 × 10<sup>9</sup>, 6.59 × 10<sup>9</sup>, and 7.97 × 10<sup>9</sup> s<sup>–1</sup> by time-resolved absorption spectroscopy, respectively.\nWe confirmed that the TET rate from PBI-OMe to PbS QDs is limited\nby the degree of orbital coupling between PBI-OMe and PbS QDs, and\nthat within a certain band gap range, samples with higher band gaps\nhave better orbital coupling and achieve faster TET rates. Our work\nprovides a straightforward and controllable platform to investigate\nthe interfacial energy transfer process between SF materials and inorganic\nsemiconductors, offering a new way to design molecule–nanocrystal\ncombinations with high photovoltaic conversion efficiency and potential\napplications in other optoelectronic fields.