Graphitic carbon nitride modified {001}-faceted TiO2 nanosheet photoanodes for efficient quantum dot sensitized solar cells

Abstract

In the present work, {001}-faceted TiO2 nanosheets were prepared via a one-step hydrothermal method and used as backbone scaffold of photoanodes of solar cells. The graphitic carbon nitride (g-C3N4) was obtained by simple solid-state heat treatment and applied to modify the {001}-faceted TiO2 nanosheet photoanodes. Compared with the photoanodes prepared from pure {001}-faceted TiO2nanosheets, the power conversion efficiency (PCE) of g-C3N4 modified {001}-faceted TiO2 nanosheet photoanodes was enhanced due to the suitable band-alignment between g-C3N4 and TiO2. With 20% loading of g-C3N4 in the photoanode, a maximum PCE of 4.23% with an open circuit voltage of 0.58 V, a short circuit current density of 15.5 mA/cm2, and a fill factor (FF) of 0.48 was achieved, giving 24.7% enhancement in the cell efficiency. Various characterizations were performed to understand the role of g-C3N4 on the device performance, and the mechanisms that account for the improvement are suggested.