Photon upconversion is an interesting phenomenon that can be used in bioimaging, photocatalysis and photovoltaics. Here, the main components being studied are the light absorbing nanocrystals (NCs) and the light emitting organic annihilator, the lead chalcogenides and rubrene respectively. Nanoparticles are used instead of conventional organic absorbers, because they are more stable and their bandgaps can be tuned by changing their size. In our experiment, the effect of the length of the aliphatic ligands attached to the NCs is being investigated. The goal of our experiments is to find the damping coefficient, or the β value for the Dexter energy transfer across aliphatic chains. In our setup, 3 nm diameter PbSe NCs serve as triplet energy donors to rubrene in toluene, and the NCs differ in the length of surface-bound aliphatic carboxylic acid functionalized ligands. The β value is obtained with time resolved measurements of the nanoparticles alone, and nanoparticles with different rubrene concentrations. The graph of τ/τ0 vs τ0*[Q] has a slope of kq, from which the β value is obtained. The Stern-Volmer quenching constant is expected to be smaller for longer ligands, since the rubrene quencher is less accessible to the NC donor.

Effect of aliphatic ligand length on triplet energy transfer from PbSe nanoparticles to rubrene

253rd National Meeting (2017)

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