TiO2微球的合成及其作为散射层在量子点敏化太阳能电池中的应用

摘要

以十六烷基三甲基溴化铵(CTAB)为模板剂,通过TiCl4在乙醇水溶液中的直接水解,制备了介孔TiO2微球. X射线衍射(XRD)结果表明所制备的微球晶型为金红石,扫描电镜(SEM)结果显示微球的直径大约为700 nm,由粒径约为16 nm的小颗粒堆积而成.通过刮涂法制备了在TiO2小颗粒层上涂覆有作为散射层的TiO2微球和未涂覆微球的薄膜.并通过化学浴沉积(CBD)的方法在膜上生长CdS/CdSe量子点,得到了量子点敏化太阳能电池(QDSCs).紫外吸收和漫反射结果表明,这种微球结构有利于量子点的沉积,具有较强的光散射作用,有效地增加了光线的收集,从而提高了电池的光电流,最终得到了4.5%的光电转换效率,比不加散射层的电池的效率高27.7%,也比利用传统散射层(由20 nm TiO2小颗粒和400 nm TiO2固体颗粒组成)的电池效率高10.2%.我们把电池效率的提升归因于较强的光散射作用和较长的电子寿命.%Mesoporous TiO2 microspheres (MSs) were successful y synthesized by the direct hydrolysis of TiCl4 in ethanol aqueous solution using cetyltrimethyl ammonium bromide (CTAB) as a template. X-ray diffraction (XRD) revealed a rutile structure for TiO2 in al the products. Scanning electron microscopy (SEM) revealed that the TiO2 microspheres had an average diameter of 700 nm, and they were composed of packed nanoparticles that had a mean size of about 16 nm. Films with or without TiO2 microspheres, as a scattering layer on top of the TiO2 nanocrystal ine layer, were prepared by the doctor-blade method. CdS/CdSe quantum dots (QDs) were grown on films by chemical bath deposition (CBD) to form QD sensitized solar cells (QDSCs). Ultraviolet-visible and diffuse reflectance spectra showed that these micro-spherical structures were favorable for the deposition of QDs and a relatively higher light scattering effect was observed. This effectively enhanced light harvesting and led to an increase in the photocurrent of the QDSCs. As a result, a power conversion efficiency of 4.5%was obtained, which is 27.7%higher than that of QDSCs without scattering layers and 10.2%higher than that of QDSCs with traditional scattering layers composed of 20 and 400 nm TiO2 solid particles. We attribute this improvement to their higher light scattering effect and longer electron lifetimes.