Preparation of AgInS2 quantum dot/In2S3 co-sensitized photoelectrodes by a facile aqueous-phase synthesis route and their photovoltaic performance

Abstract

In an aqueous-phase system, AgInS₂ quantum dot (QD) sensitized TiO₂ photoanodes were prepared in situ by the reaction of β-In₂S₃ nanocrystals and as-prepared TiO₂/Ag₂S–QD electrodes, followed by a covering process with a ZnS passivation layer. A facile successive ionic layer adsorption and reaction (SILAR) method was adopted to obtain TiO₂/Ag₂S–QD electrodes. β-In₂S₃ nanocrystals synthesized by the chemical bath deposition (CBD) process serve as the reactant of AgInS₂ as well as a buffer layer between the interfaces of TiO₂ and AgInS₂–QDs. A polysulfide electrolyte and a Pt-coated FTO glass count electrode were used to test the photovoltaic performance of the constructed devices. The characteristics of the sensitized photoelectrodes were studied in more detail by electron microscopy, X-ray techniques, and optical and photoelectric performance measurements. AgInS₂ is the main photo-sensitizer for TiO₂/AgInS₂–QD/In₂S₃ electrodes and excess In₂S₃ appears on the surface of the electrodes. Based on the optimal Ag₂S SILAR cycle, the best photovoltaic performance of the prepared TiO₂/AgInS₂–QD/In₂S₃ electrode with the short-circuit photocurrent density (J_sc) of 7.87 mA cm⁻² and power conversion efficiency (η) of 0.70% under full one-sun illumination was achieved.