柔性铜铟镓硒薄膜生长动力学与可控电化学沉积研究

Flexible copper–indium–gallium–diselenide (CIGS) thin-film solar cells, which are one of the most prospective film solar cells, have many advantages, such as high conversion efficiency, low cost and stable performance, and so on. CIGS thin film nucleation/growth kinetics mechanism has an importance role for photovoltaic performance of the cells, but the principle remains to be defined. The project uses complex deposition methods to make CIGS thin films depositing and growing on the polyimide (PI) film, and clarifies the kinetics mechanism of film growth to realize the effective union of growth kinetics and component control. The research contents contain that combining classical kinetic theory, and the growth and kinetics models of film deposition on the polyimide are built. On the electroless Cu substrate, the electro-deposition CIGS is carried out, and the onset potential of each atom electro-deposition crystallization and kinetic behavior of initial nucleation/growth during electro-deposition process are systematically studied by cyclic voltammetry, the constant potential transition and AC impedance methods. A more general model of universal dynamics is able to be established and the model is verified. According to the model, the parameters are of deposition in order to achieve to predict and control the composition of the CIGS film under different deposition conditions. The theory and method of regulating energy band are developed. The aim of research is to obtain CIGS thin film on PI film surface with excellent photovoltaic performance, and thus to lay the foundation for flexible solar cell applications.

柔性衬底铜铟镓硒(CIGS)薄膜太阳能电池具有转换效率高、成本低、性能稳定等优点，是最具发展前景的薄膜太阳能电池之一。CIGS薄膜成核/生长动力学机制对电池的光电性能有重要的调控作用，但其原理仍有待明确。本项目采用复合沉积法使CIGS薄膜在聚酰亚胺(PI)膜表面沉积生长，揭示膜生长动力学机理，将薄膜生长动力学与组成调控有效联合。研究内容：结合经典动力学理论，建立在聚酰亚胺薄膜表面化学沉积铜的生长及动力学模型；在化学沉积铜衬底上电沉积CIGS薄膜，采用循环伏安、恒电位阶跃和交流阻抗等电化学方法系统研究各原子电沉积结晶的起始电位和电沉积初期成核/生长的动力学行为，建立一个能够更具普适性的动力学通用模型，并对该模型进行验证；根据模型设置沉积参数，实现不同沉积条件下电沉积CIGS薄膜成分的精确预测和控制，发展调控薄膜能带理论和方法，以期获得光电性能优异的CIGS薄膜，为柔性太阳能电池应用奠定基础。

柔性衬底铜铟镓硒(CIGS)薄膜太阳能电池具有转换效率高、成本低、性能稳定等优点，是最具发展前景的薄膜太阳能电池之一。CIGS薄膜成核/生长动力学机制对电池的光电性能有重要的调控作用。本项目采用复合沉积法使CIGS薄膜在聚酰亚胺(PI)膜表面沉积生长，揭示了膜生长动力学机理，将薄膜生长动力学与组成调控有效联合。研究内容：结合经典动力学理论，建立在聚酰亚胺薄膜表面化学沉积铜的生长及动力学模型；在化学沉积铜衬底上电沉积CIGS薄膜，采用循环伏安、恒电位阶跃和交流阻抗等电化学方法系统研究各原子电沉积结晶的起始电位和电沉积初期成核/生长的动力学行为，建立一个能够更具普适性的动力学通用模型，并对该模型进行验证；根据模型设置沉积参数，实现不同沉积条件下电沉积CIGS薄膜成分的精确预测和控制，发展调控薄膜能带理论和方法。由以上研究获得如下结论：聚酰亚胺表面化学沉积铜的工艺为将除油后的PI膜放入85~90℃的90g/LNaOH溶液中浸渍10min后取出，放入50g/LCuSO4，80g/LNaH2PO2的活化液中反复浸渍40min后，然放入155℃烘箱中加热35min。最优化学镀铜方案为：将还原后的PI膜放入由10g/L CuSO4，19g/L EDTA，1ml HCHO，50g/L C4O6H2KNa，0.4g/L K3[Fe(CN)6]组成的镀液中，控制温度为40℃，pH为12.5，进行化学镀铜；液相沉积CIGS的最佳组分为5.0 mmol·L-1氯化铜、3.0 mmol·L-1氯化镓、3.5 mmol·L-1硫酸铟、20 mmol·L-1二氧化硒、300 μL·L-1三乙醇胺、退火温度为500 ℃，制备得到的CIGS太阳能电池光电转化效率为0.14%。通过对不同的镓含量的实验设计，确定最优的Ga/In+Ga比，当Ga/In+Ga = 3时，得到CuIn0.7Ga0.3Se2结构薄膜，经UV-vis、M-S等测试确定其禁带宽度为1.54 eV与太阳光谱更加匹配，拥有适宜的载流子浓度为8.98×1014 cm-3，平带电位为0.21 V，与ZnS材料的界面CBO仅为-0.24 eV，获得光电性能优异的CIGS薄膜，为柔性太阳能电池应用奠定基础。