期刊
ACS APPLIED MATERIALS & INTERFACES
卷 8, 期 23, 页码 14692-14700出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsami.6b05552
关键词
CdSe QDs; quantum confinement effect; quantum dot sensitized solar cell; ligand exchange; charge transfer rate; size-dependency; photovoltaics
资金
- NSF [CBET-1335821, CBET-1333649]
- U.S. Department of Energy Office of Basic Energy Sciences, Division of Materials Science and Engineering [DE-SC0002158]
- Basic Science Research Program through the National Research Foundation of Korea (NRF) - Ministry of Education [NRF-2012R1A6A3A03039474]
- Richard Perry University Professorship
- NSF CAREER Award [CBET-0846464]
- Directorate For Engineering
- Div Of Chem, Bioeng, Env, & Transp Sys [1335821, 1333649] Funding Source: National Science Foundation
Light absorption and electron injection are important criteria determining solar energy conversion efficiency. In this research, monodisperse CdSe quantum dots (QDs) are synthesized with five different diameters, and the size-dependent solar energy conversion efficiency of CdSe quantum dot sensitized solar cell (QDSSCs) is investigated by employing the atomic inorganic ligand, S2-. Absorbance measurements and transmission electron microscopy show that the diameters of the uniform CdSe QDs are 2.5, 3.2, 4.2, 6.4, and 7.8 nm. Larger CdSe QDs generate a larger amount of charge under the irradiation of long wavelength photons, as verified by the absorbance results and the measurements of the external quantum efficiencies. However, the smaller QDs exhibit faster electron injection kinetics from CdSe QDs to TiO2 because of the high energy level of CBCdSe, as verified by time-resolved photoluminescence and internal quantum efficiency results. Importantly, the S2- ligand significantly enhances the electronic coupling between the CdSe QDs and TiO2, yielding an enhancement of the charge transfer rate at the interfacial region. As a result, the S2- ligand helps improve the new size-dependent solar energy conversion efficiency, showing best performance with 4.2-nm CdSe QDs, whereas conventional ligand, mercaptopropionic acid, does not show any differences in efficiency according to the size of the CdSe QDs. The findings reported herein suggest that the atomic inorganic ligand reinforces the influence of quantum confinement on the solar energy conversion efficiency of QDSSCs.
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