球磨、压制和烧结制备铜铟镓硒薄膜及其光电特性

Among the most promising absorber materials for solar cells are Cu(In, Ga)Se2(CIGS)-based chalcopyrite materials, since CIGS is the direct band gap semiconductor material and has a high optical absorption coefficient, a tuneable band gap, an adjusted composition and somewhat benign grain boundaries. The preparation for CIGS thin film by ball-milling, compacting and sintering will be investigated. The Copper-Indium alloy, Se powders, Ga2Se3 and In2Se3 as the starting materials will be milled into CuInGaSe2 precursor paste. The paste will be coated on the substruct as the formation of the precursor layers, afterwards, the precursor layers will be sintered after compaction and the CIGS thin film will be prepared.The structure, morphology and composition of CIGS thin films will be characterized by X-ray diffraction (XRD), field emission gun scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS). The optical and electrical properties of CIGS thin film will be analyzed and the effects of the processing parameters on the precursors and CIGS thin films will be investigated. Ultimately, CIGS thin film suited for solar cells will be successfully prepared. An important advantage of this method for thin-film preparation is that films with a large area can be prepared without vacuum, using simple and low-cost equipment.

具有黄铜矿结构的Cu(In,Ga)Se2（CIGS）薄膜具有高的光吸收系数、对杂质不敏感、可调禁带、良好的晶界性能等优点，是最具有前景的光吸收材料之一。本课题采用球磨、压制和烧结三步工艺制备CIGS薄膜，采用Cu-In合金、Se粉、In2Se3和Ga2Se3为原料混合球磨制备前驱体料浆，料浆涂覆在基底上形成前驱体薄膜，前驱体薄膜压制后进行烧结得到CIGS薄膜。采用XRD、EDS、FE-SEM等测试方法表征CIGS薄膜的化学成分、相结构、薄膜致密度及表面形貌，测试CIGS薄膜的光学特性及电学特性，研究各阶段工艺参数对薄膜特性的影响规律，最终制备出适合用于太阳能电池光吸收层的CIGS薄膜。该技术优势是设备简单，非真空并且可以大面积成膜。

课题采用球磨、压制和烧结三步工艺制备CIGS 薄膜以及Ti、Cr掺杂的CuGaS2薄膜。CuSe、 Ga2Se3、 In2Se3、 Cu2S、 Ga2S3等二元化合物作为原料通过球磨制备前驱体料浆，料浆涂覆在基底上形成前驱体薄膜，前驱体薄膜压制后进行烧结。采用X射线衍射仪(XRD)、扫描电子显微镜、能谱分析EDX分析仪、紫外可见分光光度计、四探针测试仪分析了薄膜的物相结构、表面形貌、化学成分、光学特性及电学特性。研究了各阶段工艺参数对薄膜特性的影响规律和Ti、Cr掺杂浓度对CuGaS2薄膜光电特性的影响。研究表明通过添加有机分散剂和粘合剂，改进热处理工艺能改善CIGS薄膜。磷酸三丁酯比聚乙二醇更合适作为分散剂，能有效减少CIGS薄膜中的孔洞。球磨工艺可以较为精确的控制薄膜的化学组份，制备任意In/Ga比例的薄膜。烧结温度为250℃时，CIGS的黄铜矿相已经形成；随着温度的升高,二元杂相逐步消失,薄膜结晶性越来越好,当温度达到500℃时,薄膜的性能最佳，光学带隙为1.17 eV。压制工艺研究结果表明通过压制可有效改善薄膜的表面形貌和致密度。从吸收光谱图中可以看出，与未掺杂的CuGaS2薄膜的吸收光谱相比，掺杂Ti、Cr的薄膜对光的吸收明显拓宽，薄膜出现了中间带的特性。