Abstract
Cadmium sulfide (CdS) and silver sulfide (Ag2S) nanocrystals are deposited on the titanium dioxide (TiO2) nanocrystalline film on indium tin oxide (ITO) substrate to prepare CdS/Ag2S/TiO2/ITO photoelectrodes through a new method known as the molecular precursor decomposition method. The Ag2S is interposed between the TiO2 nanocrystal film and CdS nanocrystals as an energy barrier layer and a light absorber. As a consequence, the energy conversion efficiency of the CdS/Ag2S/TiO2/ITO electrodes is significantly improved. Under AM 1.5 G sunlight irradiation, the maximum efficiency achieved for the CdS(4)/Ag2S/TiO2/ITO electrode is 3.46%, corresponding to an increase of about 150% as compared to the CdS(4)/TiO2/ITO electrode without the Ag2S layer. Our experimental results show that the improved efficiency is mainly due to the formation of Ag2S layer that may increase the light absorbance and reduce the recombination of photogenerated electrons with redox ions from the electrolyte.
Highlights
Dye-sensitized photoelectrodes consisting of a wide band gap semiconductor film and a dye form the basis of many applications in photocatalytic, optoelectronic, and photovoltaic devices [1,2,3,4,5,6,7,8,9,10]
A CuInS2 nanocrystal film was formed between the TiO2 photoelectrode and Cadmium sulfide (CdS) to suppress the charge recombination in CuInS2-sensitized TiO2 photoelectrodes [19]
Unlike most of the previous studies, both Ag2S and CdS nanocrystals were synthesized through a spin coating method of using a molecular-based precursor solution
Summary
Dye-sensitized photoelectrodes consisting of a wide band gap semiconductor film and a dye form the basis of many applications in photocatalytic, optoelectronic, and photovoltaic devices [1,2,3,4,5,6,7,8,9,10]. A CuInS2 nanocrystal film was formed between the TiO2 photoelectrode and CdS to suppress the charge recombination in CuInS2-sensitized TiO2 photoelectrodes [19] Among these reported nanocrystals, Ag2S has a narrow band gap of 0.9 to 1.05 eV and a larger absorption coefficient, which makes it an important material for photovoltaic application [33,34,35]. Ag2S has a narrow band gap of 0.9 to 1.05 eV and a larger absorption coefficient, which makes it an important material for photovoltaic application [33,34,35] For these reported nanocrystals, the most commonly employed synthetic methods include solution synthesis [18,36,37], chemical bath deposition (CBD) [17,33], and successive ionic layer absorption and reaction (SILAR) [14]. The Ag2S [20,33] and CdS [17,19] nanocrystals are commonly prepared by a CBD method
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