锗掺杂二氧化钛薄膜的溶胶凝胶法制备和性能研究

Effects of germanium doping on the microstructure and photoelectrochemical properties of TiO_2 films by sol-gel method

二氧化钛是一种无毒、廉价、稳定的半导体材料,被广泛用作光电化学太阳能电池的电极材料,适当掺杂可以增强其光电性能。以钛酸丁酯和四正丁氧基锗烷为主要原料,采用溶胶-凝胶提拉涂膜法制备了Ge掺杂的TiO2薄膜。通过X射线衍射、扫描电镜、紫外-可见吸收光谱、电流-电压曲线等测试手段研究了薄膜的结晶性能、微观结构和光电性能随Ge掺杂量的变化规律。结果表明,Ge掺杂量x=0.10时,形成Ti1-xGexO2固溶体,x=0.15时,形成非晶态。掺锗后薄膜表面颗粒密度增大,薄膜比较致密。随着Ge掺杂量的增加,吸收光谱吸收边蓝移,光电化学性能也得到一定提高。在Ge掺杂量为0.05时,光电流达到最大值17A/m2。同时,研究了锗掺杂对光电流的影响。

Photoelectrochemical （PEC） solar cells have attracted considerable attention as one of the most effective ways to utilize solar energy. As a cheap and stable semiconductor material, TiO2 has been frequently used in the PEC solar cells. Doping is one of the most effective ways to enhance the photoelectrochemical properties of TiO2 thin film electrodes. So far,many efforts have been made to synthesize doped TiO2 photoelectric films to develop the photoelectrochemical performance. In this study, germanium doped TiO2 thin films have been synthesized by sol-gel dip-coating method using butyl titanate （Ti （OC4 H9 ）4 ） and tetra-n-butoxygermane （Ge[O （CHz）sCH3 ]4） as the titania and germania precursors, respectively. X-ray powder diffraction （XRD）, scanning electron microscope （SEM） attached with energy dispersive X-ray spectroscopy （EDS）,optical absorption spectra,and current-potential （I-V） curves have been studied for the prepared Ge-doped TiO2 thin films. The results revealed that Til-~GexO~ solid solution formed when x=0. 10,while the film exists amorphous when x=0. 15. The anatase crystal structure was clestroyed gradually with increasing germanium amount. Doping germanium reduced the grain size. The surface morphology of Ge-doped films showed higher particle density than that of pure TiO2,hence increasing the active site numbers and improving the photoelectrochemical properties. The increase of Ge amount caused a gradual blue shift of optical absorption edge in UV-Vis absorption spectra. The photocurrent was enhanced with proper doping amount, owing to more active sites and comparatively better crystallinity. The maximum value of photocurrent reached 17A/m^2 when germanium amount was 0. 05. The mechanism of effects of Ge-doping on the photocurrent of TiO2 thin film electrodes was also investigated.