高效CdS/CdSe双量子点共敏化硼/硫共掺杂纳米TiO2太阳能电池的制备及界面电荷传输机理的研究

Quantum-dot-sensitized solar cells (QDSCs) have attracted much attention as a hot research area thoughout the world, which dyes are replaced by inorganic narrow-band semiconductor quantum dots (QDs). Especially, their optical absorption spectra can be tailored by changing their size and composition, which makes them have important applications in photovoltaic devices. The key problem of the QDSCs research is how to realize quantum dots assembling into the mesoporous TiO2 matrix to obtain efficient loading, and how to improve the transmission capacity of the charge carriers as well as borden the absorption spectral range. This project will be proposed to combine the CdS/ CdSe co-sensitization and nonmetal Boron an Sulfur codoping together, improving the visible absorption and photoelectric performance through its synergistic effect. Through out the optimization of chemical properties , such as the composition, microstructure, spectral response range and the band gap of the composite electrodes, which will be obtained by adjusted the local energy level with high photoelectric conversion efficiency and well stability, thus to assemble the solar cells with high performance. Moreover, the band gap position of semiconductor quantum dot sensitized solar cells is adjusted by controlling their size, thus, it can be realized the best match of the relative conduction band level position between each interface, as a result to establish the interface charge transport mechanism model. The research findings of this project will provide experimental basis and theoretical reference for a higher level design of perfect performance of nano device sensitized by quantum dot which take advantage of solar energy.

利用窄带隙半导体量子点替代染料做光敏剂应用于敏化太阳能电池是目前国内外研究的热点。其通过改变尺寸和组成来调控光谱吸收范围的优势在光伏领域具有重要应用前景。实现量子点在TiO2表面的高效均匀沉积、提高电极载流子传输能力、拓宽光谱吸收范围是目前量子点敏化太阳能电池研究的关键问题。本项目拟将CdS/ CdSe量子点共敏化和非金属硼/硫共掺杂这两种使TiO2吸收边发生红移的有效方法结合起来，利用其协同作用，提高可见光吸收及光电性能。通过优化复合电极的组成、微观结构、光谱响应范围、能隙等物化性能，得到能级局部可调的具有更高光电转换效率和稳定性的复合电极，实现高性能太阳能电池的组装。通过尺寸控制来调节量子点能带位置，实现各界面相对能级位置的最佳匹配，建立界面电荷传输机理模型。本项目研究成果将为在更高层次上设计制备高性能量子点敏化太阳能纳米器件提供实验基础和理论依据。

利用窄带隙半导体量子点替代染料做光敏剂应用于敏化太阳能电池是目前国内外研究的热点。其通过改变尺寸和组成来调控光谱吸收范围的优势在光伏领域具有重要应用前景。实现量子点在TiO2表面的高效均匀沉积、提高电极载流子传输能力、拓宽光谱吸收范围是目前量子点敏化太阳能电池研究的关键问题。.采用水热法制备硼硫(B/S)共掺杂纳米二氧化钛(B-S-TiO2)，并配制成浆料，利用丝网印刷技术在FTO导电玻璃上制备B-S-TiO2薄膜；用化学浴沉积(CBD)法制备了CdS/CdSe量子点敏化B-S-TiO2薄膜电极，并用X射线衍射（XRD）、电子显微镜(TEM)、元素分析能谱（EDS）和紫外-可见光谱对其进行表征分析；结果显示B/S共掺杂不会改变TiO2的晶型，掺杂后的TiO2吸收边带发生明显红移，吸收强度显著增强。TEM结果显示粒径均匀分布，大约为10-18nm，采用化学浴沉积法用CdS/CdSe双量子点敏化B-S-TiO2薄膜表面，TEM结果显示CdS/CdSe双量子点均匀沉积到B-S-TiO2薄膜内部，量子点尺寸大约为5nm。.利用光电流-电势曲线与光电流作用谱考察了 B-S-TiO2/CdS半导体复合薄膜电极的光电化学性能及实验条件的改变对薄膜电极光电性能的影响。借助于表面光电压谱和瞬态光电流谱探讨了 B-S-TiO2/CdS薄膜电极中电荷传输过程。实验结果表明，窄带隙半导体 CdS 与宽带隙半导体 TiO2的复合有效地促进了光电子与空穴的分离，增大了薄膜电极的光电流，改善了 B-S-TiO2/CdS薄膜电极初始光电流响应，B-S-TiO2/CdS半导体复合薄膜电极的光电响应拓宽至 500 nm 的可见光区，在 400 nm 单色光照射下半导体复合薄膜电极具有约 45%的光电转换效率。.利用阴极恒电位沉积法将窄带隙半导体 CdSe 沉积于B-S-TiO2多孔纳米晶薄膜中。通过 XRD、SEM 等测试 手 段 表 征 了 沉 积 物CdSe 的晶相结构与粒子尺寸、分析了所制备的B-S-TiO2/CdSe 的组成及表面形貌。讨论了在不同沉积电位下 CdSe 的沉积机理。利用紫外-可见吸收光谱、表面光电压谱、电流-电势曲线及瞬态光电流谱等考察了B-S-TiO2/CdSe 薄膜的光电性能。实验结果表明，窄带隙半导体 CdSe 纳米粒子以球体较均匀地分布形成较致密、平整的表面形貌，粒子的