Shell-Dependent Energy Transfer from 1,3,5-Tris(N-phenylbenzimidazol-2,yl) Benzene to CdSe Core/Shell Quantum Dots

Abstract

We studied the energy transfer between CdSe core/shell quantum dots (QDs) and 1,3,5-tris(N-phenylbenzimidazol-2,yl) benzene (TPBI) in inorganic/organic blend films using steady-state and time-resolved photoluminescence (PL) spectroscopy. The shortening in PL lifetime of TPBI molecules and the resulting lengthening in PL lifetime of the QDs demonstrated an efficient energy transfer process from donor to acceptor. The slowest PL decays of CdSe core/shell QDs observed in the blend films with low QD concentration were considered to result from the maximum energy transfer process from the surrounding TPBI molecules of a QD to itself. The PL decay curves of the core/shell QDs with a CdS, ZnS, and CdS/ZnCdS/ZnS shells were simulated to obtain the excited state lifetimes of the surrounding TPBI molecules for understanding the effect of the shells on the energy transfer process. It was surprisingly found that the obtained energy transfer rate to a QD with a thick CdS/ZnCdS/ZnS multishell from the surrounding TPBI ...