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Lookup NU author(s): Dr Pablo Docampo
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Surface oxidation of quantum dots (QDs) is one of the biggest challenges in quantum dot-sensitized solar cells (QDSCs), because it introduces surface states that enhance electron-hole recombination and degrade device performance. Protection of QDs from surface oxidation by passivating the surface with organic or inorganic layers can be one way to overcome this issue. In this study, solid-state QDSCs with a PbS QD absorber layer were prepared from thin mesoporous TiO2 layers by the successive ionic layer adsorption/reaction (SILAR) method. Spiro-OMeTAD was used as the organic p-type hole transporting material (HTM). The effects on the solar cell performance of passivating the surface of the PbS QDs with the tripeptide l-glutathione (GSH) were investigated. Currentâ€"voltage characteristics and external quantum efficiency measurements of the solar cell devices showed that GSH-treatment of the QD-sensitized TiO2 electrodes more than doubled the short circuit current and conversion efficiency. Impedance spectroscopy, intensity-modulated photovoltage and photocurrent spectroscopy analysis of the devices revealed that the enhancement in solar cell performance of the GSH-treated cells originates from improved charge injection from PbS QDs into the conduction band of TiO2. Time-resolved photoluminescence decay measurements show that passivation of the surface of QDs with GSH ligands increases the exciton lifetime in the QDs.
Author(s): Jumabekov AN, Cordes N, Siegler TD, Docampo P, Ivanova A, Fominykh K, Medina DD, Peter LM, Bein T
Publication type: Article
Publication status: Published
Journal: ACS Applied Materials & Interfaces
Print publication date: 15/01/2016
Acceptance date: 15/01/2016
ISSN (print): 1944-8244
ISSN (electronic): 1944-8252
Publisher: American Chemical Society
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