银金修饰TiO_2纳米管阵列光阳极的制备及其光伏性质

Fabrication and Photovoltaic Properties of Ag/Au Modified TiO_2 Nanotube Arrays

采用阳极氧化法,以金属钛箔为原料制备了TiO2纳米管阵结构染料敏化纳米晶太阳能电池(DSSC)光阳极,并用电沉积、光沉积和真空蒸发法对其表面分别进行金属Ag和Au修饰。对金属修饰前后的光阳极用扫描电子显微镜(SEM)和X射线衍射分析仪(XRD)表征发现:阳极氧化法制备的TiO2纳米管阵列结构规整有序;经过化学沉积后,其表面均覆盖有一层致密的金属粒子薄膜。测量光电流密度-电压(J-V)曲线和电化学阻抗谱(EIS)发现:相比纯TiO2纳米管阵列,经过Ag修饰后的TiO2阵列其短路电流密度和开路电压最大可以分别提高到前者的4.9和1.7倍,并且其电化学阻抗出现显著降低。研究表明:金属Ag修饰改善了TiO2纳米管之间的连通性,提高了TiO2光阳极中电子的传输效率,并通过等离子共振激发出光电子,同时与TiO2相互作用,使其在可见光区域也能够促进电子-空穴对的分离。

TiO2 nanotube arrays for dye - sensitized nanocrystal solar cell （DSSC） photoanode were fabricated by the anodization from titanium foil and modified with Ag and Au on its surface using electrodeposition, photodeposition and vacuum sputtering, respectively in this paper. The scanning electron microscope （SEM） images and X- ray diffraction （XRD） patterns show that TiO2 nanotube arrays have regular and orderly structure and are covered by a close nanopaticle film of silver and gold. In contract to pure TiO2 nanotube arrays, the TiO2 array modified with Ag has higher short circuit current density and larger open circuit voltage, which can be enhanced 3.9 and 0.7 times larger than the former, and its electrochemical impedance is reduced significantly as observed from electrochemical impedance spectroscopy （EIS） patterns and photocurrent density -voltage （J -V） curves. It shows that Ag modification improves the connectivity among TiO2 nanotubes, assists electron transfer inside the TiO2 nanotubes, and excites photoelectron by surface plasmon resonance, meanwhile promotes the electron - hole separation inside the TiO2 crys- tals in visible wavelength range through interaction with TiO2.