Enhanced photovoltaic performance of solar cell based on front-side illuminated CdSe/CdS double-sensitized TiO2 nanotube arrays electrode

Free-standing TiO2 nanotube (NT) arrays have been prepared by a two-step anodization method. These translucent TiO2 NT arrays can be transferred to the fluorine-doped tin oxide glass substrates to form front-side illuminated TiO2 NT electrodes. The TiO2 NT electrodes were double-sensitized by CdSe/CdS quantum dots (QDs) through successive ionic layer adsorption and reaction (SILAR) process. The absorption range of the TiO2 NT electrode was extended from similar to 380 to 700 nm after sensitization with CdSe/CdS QDs. The SILAR cycles were investigated to find out the best combination of CdS and CdSe QDs for photovoltaic performance. The power conversion efficiency of 2.42 % was achieved by the CdSe(10)/CdS(8)/TiO2 NT solar cell. A further improved efficiency of 2.57 % was obtained with two cycles of ZnS overlayer on the CdSe(10)/CdS(8)/TiO2 NT electrode, which is 45.19 % higher than that of back-side illuminated solar cell. Furthermore, the ZnS(2)/CdSe(10)/CdS(8)/TiO2 NT solar cell possesses a higher stability than CdSe(10)/CdS(8)/TiO2 NT solar cell during the same period. The better photovoltaic performance of the ZnS(2)/CdSe(10)/CdS(8)/TiO2 NT solar cell has demonstrated the promising value to design quantum dots-sensitized solar cells with double-sensitized front-side illuminated TiO2 NT arrays strategy.