Enhancing Performance of CdS Quantum Dot-Sensitized Solar Cells by Two-Dimensional g-C3N4 Modified TiO2 Nanorods

Abstract

In present work, two-dimensional g-C₃N₄ was used to modify TiO₂ nanorod array photoanodes for CdS quantum dot-sensitized solar cells (QDSSCs), and the improved cell performances were reported. Single crystal TiO₂ nanorods are prepared by hydrothermal method on transparent conductive glass and spin-coated with g-C₃N₄. CdS quantum dots were deposited on the g-C₃N₄ modified TiO₂ photoanodes via successive ionic layer adsorption and reaction method. Compared with pure TiO₂ nanorod array photoanodes, the g-C₃N₄ modified photoanodes showed an obvious improvement in cell performances, and a champion efficiency of 2.31 % with open circuit voltage of 0.66 V, short circuit current density of 7.13 mA/cm², and fill factor (FF) of 0.49 was achieved, giving 23 % enhancement in cell efficiency. The improved performances were due to the matching conduction bands and valence bands of g-C₃N₄ and TiO₂, which greatly enhanced the separation and transfer of the photogenerated electrons and holes and effectively suppressed interfacial recombination. Present work provides a new direction for improving performance of QDSSCs.