Direct aqueous synthesis of quantum dots for high-performance AgInSe2 quantum-dot-sensitized solar cell

• Published in: Journal of power sources Vol. 354; pp. 100 - 107
• Main Authors: Li, Pei-Ni, Ghule, Anil V., Chang, Jia-Yaw
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 30.06.2017
• Subjects: AgInSe2; Aqueous synthesis; Quantum dots; Quantum dots-sensitized solar cells; Quantum dots-sensitized solar cells; AgInSe2; Quantum dots; Aqueous synthesis
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2017.04.040

Compared to the use of an organic system, a synthetic method based on aqueous solutions offers the potential for simple, environmentally friendly, low-cost fabrication with high synthetic reproducibility and easy upscaling. Here, AgInSe2 quantum dots (QDs) capped with different types of thiol molecules [thioglycolic acid (TGA), 3-mercaptopropionic acid (MPA), or glutathione (GSH)] are prepared within 15 min in aqueous media under microwave irradiation. The GSH-stabilized AgInSe2 QDs are demonstrated to be effective light harvesters in a QD-sensitized solar cell (QDSSC), showing ∼23% better efficiency than cells using TGA- and MPA-stabilized AgInSe2 QDs. The performance enhancement is attributed to the multidentate chelating effect of the GSH stabilizer, which provides efficient charge injection from QDs into the conduction band of TiO2 in the photoanode. Electrochemical impedance spectroscopy and intensity-modulated photocurrent spectroscopy/intensity-modulated photovoltage spectroscopy measurements are adopted for more detailed study of the interfacial properties and electron transport characteristics of these AgInSe2 QDSSCs. More importantly, the GSH-stabilized AgInSe2 QDSSC with TiCl4 treatment exhibits an excellent power conversion efficiency of 5.69% with an average value of 5.48 ± 0.19% under 100 mW cm−2 illumination, which is one of the highest values observed for a QDSSC sensitized with a Ag-based metal chalcogenide. Glutathione-stabilized AgInSe2 quantum dots were prepared in an aqueous phase; the optimal AgInSe2-quantum-dot-sensitized solar cell exhibited a high conversion efficiency of 5.68%. [Display omitted] •Glutathione-stabilized AgInSe2 quantum dots are prepared by an aqueous route.•AgInSe2 quantum dots show a broad absorbance spectrum and red emission.•The solar cell's interfacial properties are studied using impedance spectroscopy.•The AgInSe2-quantum-dot-sensitized solar cell exhibits excellent performance.