Performance of Sol-Gel Synthesized Nanocrystalline TiO2 in Quantum Dot Sensitized Solar Cell with Deposition of CdS/CdSe Quantum Dots by Different Techniques

Quantum dot sensitized solar cells (QDSSCs) are promising third-generation photovoltaic devices in which nanocrystalline TiO2 is used as a photoanode and plays an essential role. In this study, nanocrystalline TiO2 was prepared using a simple sol gel technique with oleic acid, triethanolamine, and titanium isopropoxide. The structure and morphology of the prepared nanocrystalline TiO2 was characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Two techniques, chemical bath deposition (CBD) and successive ionic layer adsorption and reaction (SILAR), were used to deposit CdS quantum dots (QDs) on the TiO2 surface. Compared with CBD, SILAR yields more efficient cells, but it is a lengthier process. Both the CBD and SILAR methods were used in single cell preparation for comparison and to reduce the deposition time in the SILAR process. CdS and CdSe were used as co-sensitizers for the QDSSCs. CdS deposition alone did not significantly improve efficiency in either technique, but CdS/CdSe co-sensitizers on nanocrystalline TiO2 exhibited a higher efficiency than those with only CdS. The performance of both techniques in QDSSC applications is discussed in detail.