CdS敏化纳晶TiO2薄膜电极的光电化学性能研究/PHOTOELECTROCHEMICAL PROPERTIES OF THE CdS SENSITIZED T

2018-11-22 08:34:05

光电 电极 TiO2 复合 CdS



自1991年以来,有机染料敏化太阳能电池成为太阳能研究领域的一个研究热点,研究工作者进行了大量的试验来提高太阳能电池的光电转换效率。而通过调整吸附在TiO2表面的有机染料分子的光学吸收性能是提高太阳能光电转换效率最重要的方法之一。
无机纳米半导体材料,由于其特殊的量子尺寸效应导致其光学吸收性质随着纳米颗粒的尺寸变化而发生改变,因此成为一种可取代有机染料分子的光敏材料。在本论文中,我们制备了CdS敏化TiO2复合电极,并研究了复合电极的光电化学性能。
首先采用“手术刀法”制备了TiO2纳晶薄膜电极,并通过连续离子吸附反应技术将CdS沉积在TiO2电极表面形成CdS/TiO2复合薄膜电极。通过对CdS/TiO2复合薄膜电极的光学吸收性能研究表明,改变CdS的沉积次数可有效控制TiO2电极表面CdS的沉积量。SEM及XRD研究结果表明,在我们的实验条件下,无论是否进行加热后处理CdS在TiO2电极表面均形成具有立方晶相的纳米颗粒;CdS纳米颗粒在电极表面发生一定程度的聚集,其聚集的程度与制备条件有关。研究同时表明,制得CdS/TiO2复合薄膜电极具有纳米多孔的结构,而这种纳米多孔膜结构是太阳能电池获得高效光电转换的重要条件之一。
其次采用不同的添加剂对TiO2薄膜电极进行了前处理,并研究了前处理对复合电极光电化学性能的影响。结果表明采用0.1M 尿素和2 g/L PEG的混合溶液对TiO2薄膜电极进行前处理后制得的CdS/TiO2复合电极具有最好的光电化学性能。同时发现前处理对复合电极光电化学性能的影响与复合电极是否进行加热后处理有关。对于进行了加热后处理的复合电极,前处理能同时提高CdS/TiO2复合电极的光电压及光电流;而当复合电极不进行加热后处理时,前处理对光电流及光电压没有产生明显的影响,但却提高了太阳能电池的填充因子。




Dye sensitized solar cells (DSSC) have been an active research project since 1991, and lots of trials have been made in order to enhance its solar energy conversion efficiency. One of the most important approaches is to tuning the absorption spectra of the organic dyes, being anchored onto the TiO2 surface.
The special size-select optical property of the inorganic semiconductor nanocrystal makes it easy to tune the absorption spectrum of inorganic semiconductor particles and thus inorganic semiconductor can be an alternative candidate instead of organic dyes to fabricate a solar cell. Based on this consideration, we prepared the CdS sensitized TiO2 nanocrystal thin film electrode, and its photoelectrochemical properties have been investigated.
TiO2 nanocrystal thin film was prepared by the doctor blade method, and the CdS sensitized TiO2 electrodes were obtained by depositing CdS onto the TiO2 surface via a simple successive ionic layer adsorption reaction technique. The amount of CdS deposited on TiO2 was controlled by the CdS deposition cycle as proved by the UV-Vis spectra. The surface morphology and the crystalline structure were confirmed by SEM and XRD investigations. The CdS was found to be crystallized with cubic crystalline structure in our experiment condition even without heat-treated. It is also found that the CdS particles on the TiO2 surface show to aggregate together depending on the preparation conditions. However, the porous structure of TiO2 film was not affected by the CdS deposition in all the cases, which is a must for constructing an efficient solar cell.
Aiming to improve the photoelectrochemical properties, different kinds of additives were used to pretreat the TiO2 film. The best one was found to be the mixture of 0.1 M of urea and 2 g/L of PEG. Detailed photoelectrochemical investigations show that the pretreatment has different effects depending on whether the CdS/TiO2 was subjected to the post heattreatment or not. A large increase of both photocurrent and photovoltage was found after the pretreatment while the CdS/TiO2 was post-heattreated. In the case of CdS/ TiO2 were not subjected to the post heattreatment, the pretreatment has no obviously effect on both photocurrent and photovoltage. However, the fill factor of the resulted solar cell was largely increased by the pretreatment.