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

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.