基于能带调控Cu2ZnSn(SxSe1-x)4薄膜电池中新型无毒缓冲层的制备及界面物理问题的研究

Cu2ZnSn(SxSe1-x)4 (CZTSSe)薄膜太阳能电池由于其制备工艺简单、成本低、环境友好等优点而倍受重视。然而，低器件效率限制了其发展和应用，主要原因是吸收层与缓冲层间的界面不匹配导致的开路电压低。针对以上问题，本项目提出利用磁控溅射和电化学沉积技术，通过对薄膜组分和能带结构进行调控，获得（112）择优取向的低阻CZTSSe薄膜，阐明化学计量比对薄膜的晶粒尺寸、电阻率和带隙宽度的影响规律；在获得的CZTSSe薄膜上沉积高质量ZnSe薄膜作为缓冲层，研究能带排列和界面缺陷态密度对CZTSSe的成分比例和缓冲层厚度的依赖关系，给出最优的CZTSSe薄膜的化学计量比和缓冲层制备条件；制备以ZnSe为缓冲层的CZTSSe太阳能电池，分析缓冲层性能及界面处的晶格失配和带偏移影响光生载流子的分离、复合和输运的物理机制，探索提高开路电压的工艺方法和技术途径。

Cu2ZnSn(SxSe1-x)4 (CZTSSe) has attracted much attention for its advantages of simple fabrication technique, low cost and environment-friendly. It is well known that the difficulty in the application of CZTSSe thin film solar cells is low energy conversion efficiency, which is mainly due to the low open circuit voltage reduced by interface mismatch between the buffer layer and CZTSSe. To solve the above problem, it is suggested that to obtain high quality CZTSSe thin films with (112) preferred orientation and low resistivity by using magnetron sputtering or electrochemical deposition via adjusting the stoichiometry and band structure of CZTSSe thin films. Clarify the effect of stoichiometry of CZTSSe thin film on grain size, resistivity and band gap of CZTSSe. By using high quality ZnSe thin film as buffer layer, studying the dependence of band alignment and the interface density of native defect on the composition of CZTSSe and thickness of buffer layer to obtain the optimal stoichiometry of CZTSSe thin film and suitable method and technique of buffer layer deposition. To prepare CZTSSe based solar cell by inducing ZnSe as buffer layer, investigating the physical mechanism of the buffer layers’ properties as well as lattice mismatch and band offset between the buffer layers and CZTSSe on the segregation, recombination and transportation of photo-generated carrier. Exploring the method and technique of improvement of open circuit voltage.