Enhance the performance of dye-sensitized solar cells by Bi2Te3 nanosheet/ZnO nanoparticle composite photoanode

Hexagonal Bi2Te3 nanosheets with uniform morphology were facilely synthesized through a hydrothermal method at 180 °C. X ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and selected area electron diffraction (SAED) were employed to characterize the Bi2Te3 nanosheets. The results clearly indicate that uniform Bi2Te3 nanosheets with a side length of 300-400 nm were obtained. Bi2Te3 nanosheet/ZnO nanoparticle (Bi2Te3 NS/ZnO NP) composite photoanodes were fabricated with Bi2Te3 NS concentration in the range of 0-0.25 at.%. The effect of Bi2Te3 NS contents in composite photoanode on the performance of dye-sensitized solar cells (DSSCs) was systematically investigated. The photocurrent density-voltage (J-V) characteristics indicate that the DSSCs with Bi2Te3 NS/ZnO NP composite photoanode exhibit significantly improved photovoltaic performance. Typically, the highest energy conversion efficiency of 4.10% which is increased by 46.95% compared with that of the bare ZnO can be achieved in the DSSC with 0.15 at.% Bi2Te3 NS embedding. The EIS results further confirm that a moderate amount of Bi2Te3 NS in photoanode could not only improve the electrons transport and suppress the charge recombination rate, but also enhance the electron collection efficiency. Furthermore, the excellent thermoelectric performance of Bi2Te3 NS in the photoanode could greatly increase the electron density and lower the temperature of the DSSCs effectively. All these results suggest that the Bi2Te3 NS/ZnO NP composite photoanode could highly enhance the performance of the DSSCs.