Quantum Dot Sensitized Solar Cells Based on TiO 2 /AgInS 2

Quantum dot heterojunctions with type-II band alignment can efficiently separate photogenerated electron-hole pairs and, hence, are useful for solar cell studies. In this study, a quantum dot sensitized solar cell (QDSSC) made of TiO 2 /AgInS 2 is achieved to boost the photoconversion efficiency for the TiO 2 -based system by varying the AgInS2 layer’s thickness. The TiO 2 nanorods array film is prepared by using a simple hydrothermal technique. The formation of a AgInS2 QD-sensitized TiO 2 -nanorod photoelectrode is carried out by successive ionic layer adsorption and reaction (SILAR) technique. The effect of the QD layer on the performance of the solar cell is studied by varying the SILAR cycles of the QD coating. The synthesized electrode materials are characterized by using X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, high resolution transmission electron microscopy and solar cell performances. The results indicate that the nanocrystals have effectively covered the outer surfaces of the TiO 2 nanorods. The interfacial structure of quantum dots (QDs)/TiO 2 is also investigated, and the growth interface is verified. A careful comparison between TiO 2 /AgInS 2 sensitized cells reveals that the trasfer of electrons and hole proceeds efficiently, the recombination is suppressed for the optimum thickness of the QD layer and light from the entire visible spectrum is utilised. Under AM 1.5G illumination, a high photocurrent of 1.36 mAcm −2 with an improved power conversion efficiency of 0.48% is obtained. The solar cell properties of our photoanodes suggest that the TiO 2 nanorod array films co-sensitized by AgInS 2 nanoclusters have potential applications in solar cells.