Efficient electronic communication between the inorganic nanocrystals (NCs) and organic ligands underlies the performance of a hybrid system. While it is critical to engineer organic ligands to increase the binding affinity and orbital overlap, it is challenging to design ligands because of the difficulties in characterizing the NC surface, which may deviate in unpredictable ways from the bulk. In this work, a series of isomeric bidentate bis-pyridine anthracene ligands that slightly differ in their binding geometries are presented. Steady state photon upconversion experiment indicates that the binding geometry plays a crucial role, with the upconversion quantum yield spanning a high of 13.9% to a low of 2.1%. Ultra-fast transient absorption measurements indicate that the high performance is due the improved rate of triplet energy transfer, which originates from the complementary binding geometry of one particular ligand to the NC surface. The use of bidentate ligands here demonstrates a novel way to promote orbital overlap between hybrid donors and acceptors to boost energy or charge transfer.<br/>

Lock and key bidentate binding of ligands on nanocrystals

253rd National Meeting (2017)

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