Enhancing photo-reduction quantum efficiency using quasi-type II core/shell quantum dots

Chemical Science
Yanyan JiaTianquan Lian

Abstract

Quantum confined semiconductor nanocrystals have emerged as a new class of materials for light harvesting and charge separation applications due to the ability to control their properties through rational design of their size, shape and composition. We report here a study of enhancing the quantum yield of methyl viologen (MV2+) photoreduction using colloidal quasi-type II CdSe/CdS core/shell quantum dots (QDs). The steady-state quantum yield of MV+˙ radical generation, in the presence of thiols as sacrificial donors, increased monotonically with the CdS shell thickness within the studied thickness regime (0-4.7 CdS monolayers). Using ultrafast transient absorption and time-resolved photoluminescence decay spectroscopy, we found that both the rates of electron transfer from the QD to MV2+ and the subsequent charge recombination in QD+-MV+˙ complexes decreased exponentially with the shell thickness, consistent with calculated 1S electron and hole densities at the QD surfaces, respectively. Interestingly, the hole transfer rate remained relatively independent of shell thickness, likely due to a cancellation of the reduction of hole transfer coupling strength with the increased number of hole acceptor ligands on the QD surface at l...Continue Reading

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Citations

Mar 6, 2019·Physical Chemistry Chemical Physics : PCCP·Amar Nath YadavKedar Singh
Dec 2, 2017·Chemistry : a European Journal·Jayanta DanaHirendra N Ghosh
May 26, 2017·ACS Applied Materials & Interfaces·Pallavi SinghalSuman Neogy
Jul 28, 2017·Langmuir : the ACS Journal of Surfaces and Colloids·Pallavi SinghalHirendra N Ghosh
Sep 2, 2016·Journal of the American Chemical Society·Hongjin LvRichard Eisenberg

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