高效宽光谱吸收双量子点敏化ZnO太阳能电池的可控构筑及光电性能研究

Using inorganic narrow-band semiconductor quantum dots (QDs) to replace dyes is a commonly used method in sensitized solar cells, can control by changing the size and composition of absorption characteristics of the range. 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 ZnO 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 improving the visible absorption and photoelectric performance. 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常用手段，其具有通过改变尺寸和组成来调控光谱吸收范围的特性。实现量子点在ZnO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量子点共敏化使ZnO吸收边发生红移，提高可见光吸收及改善光电性能。通过优化复合电极的组成、微观结构、光谱响应范围、能隙等理化性能，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。

绿色高效、低成本的太阳能电池技术的应用被认为是解决传统化石能源危机、全球环境污染和气候变暖等一系列环境问题的有效途径。量子点敏化太阳能电池（QDSSCs）因作为第三代典型太阳能电池的代表，不仅具有超高的理论光电转换效率，且制备方法简易，生产成本低等优势而受到广泛关注。其中量子点材料具有高的吸光效率、量子尺寸效应和多激子效应，其敏化构型对材料的依赖性以及其制备工艺简单等诸多优势，QDSSCs被认为是最具潜力的新一代太阳能电池之一。近年来，QDSSCs 研究迅速发展，光阳极作为其中重要的组成部分之一，其结构的优化可有效改善电池性能。. 本项目采用高压水热法制备纯的纳米ZnO样品，配制成浆料，采用丝网印刷技术制备ZnO薄膜。用化学浴沉积(CBD)法制备了CdS/CdSe量子点敏化ZnO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。分析了不同尺寸的CdS/CdSe双量子点在水相和纯有机相中ZnO多孔纳米薄膜表面的沉积效果，研究了不同尺寸量子点CdS和CdSe分别沉积到ZnO多孔纳米薄膜表面的可控制备条件，确定了量子点敏化ZnO多孔纳米晶制备的最佳工艺。采用光谱分析手段，研究了影响能级调控的关键因素及复合电极的最佳能级匹配关系。采用电化学手段，研究了电荷在量子点敏化ZnO电极及器件中的转移、传输过程及机理，分析了量子点的尺寸、形状、密度、分布、有序性及其介孔匹配性对纳米ZnO薄膜电极光电性能的影响规律，进而探讨了量子点敏化机理。