Evolution from Tunneling to Hopping Mediated Triplet Energy Transfer from Quantum Dots to Molecules
Artikel i vetenskaplig tidskrift, 2020

Efficient energy transfer is particularly important for multiexcitonic processes like singlet fission and photon upconversion. Observation of the transition from short-range tunneling to long-range hopping during triplet exciton transfer from CdSe nanocrystals to anthracene is reported here. This is firmly supported by steady-state photon upconversion measurements, a direct proxy for the efficiency of triplet energy transfer (TET), as well as transient absorption measurements. When phenylene bridges are initially inserted between a CdSe nanocrystal donor and anthracene acceptor, the rate of TET decreases exponentially, commensurate with a decrease in the photon upconversion quantum efficiency from 11.6% to 4.51% to 0.284%, as expected from a tunneling mechanism. However, as the rigid bridge is increased in length to 4 and 5 phenylene units, photon upconversion quantum efficiencies increase again to 0.468% and 0.413%, 1.5 1.6 fold higher than that with 3 phenylene units (using the convention where the maximum upconversion quantum efficiency is 100%). This suggests a transition from exciton tunneling to hopping, resulting in relatively efficient and distance-independent TET beyond the traditional 1 nm Dexter distance. Transient absorption spectroscopy is used to confirm triplet energy transfer from CdSe to transmitter, and the formation of a bridge triplet state as an intermediate for the hopping mechanism. This first observation of the tunneling-to-hopping transition for long-range triplet energy transfer between nanocrystal light absorbers and molecular acceptors suggests that these hybrid materials should further be explored in the context of artificial photosynthesis.

Författare

Zhiyuan Huang

University of California at Riverside

Zihao Xu

Emory University

Tingting Huang

University of California at Riverside

Victor Gray

Chalmers, Kemi och kemiteknik, Kemi och biokemi

Kasper Moth-Poulsen

Chalmers, Kemi och kemiteknik, Tillämpad kemi, Kasper Moth-Poulsen Group

Tianquan Lian

Emory University

Ming Lee Tang

University of California at Riverside

Journal of the American Chemical Society

0002-7863 (ISSN) 1520-5126 (eISSN)

Vol. 142 41 17581-17588

Ämneskategorier

Oorganisk kemi

Atom- och molekylfysik och optik

Den kondenserade materiens fysik

DOI

10.1021/jacs.0c07727

PubMed

32969652

Mer information

Senast uppdaterat

2020-12-02