Elemental sulfur-based electrodeposition of indium sulfide films

We report research on electrodeposition of indium sulfide films, with In2S3 a less hazardous alternative to CdS buffer layers in solar cells. Numerous organic and aqueous/organic electrolytes of InCl3, NaCl, and elemental sulfur were investigated, including several glycols and amides. Temperatures ranged from 80-170°C, and deposition voltages from -0.6 to -1.2 V (Ag/AgCl with organic filling solution). Substrates included indium tin oxide-on-glass, molybdenum, and titanium, with indium or graphite anodes. Rapid stirring was used. Deposition was sluggish in all baths. Uniformity and adherence were only moderate, with irregular coverage and cracking-and-flaking sometimes evident. The best baths were ethylene glycol or 1, 2-propanediol-based, with golden-yellow films, nominally In2S3-xOx, depositing typically heavier around the substrate edges. With low temperatures and/or large currents, brown films more rich in indium sometimes formed. Cyclic voltammetry elucidated onset potentials, secondary reactions, and photoactivity, with the greatest anodic photocurrents arising from In2S3's n-type conductivity occurring with mixed ethylene glycol/propionic acid/water baths. Scanning electron microscope photographs indicated a compact small grain microstructure for yellow films. Energy dispersive X-ray analysis and photoelectron spectroscopy data indicate up to 15% oxygen content.

本研究报道了硫化铟薄膜的电沉积工艺，其中硫化铟（In₂S₃）可作为太阳能电池中硫化镉（CdS）缓冲层的低毒替代材料。研究了以三氯化铟（InCl₃）、氯化钠（NaCl）及单质硫为溶质的多种有机、水-有机复合电解液，涵盖多种二醇与酰胺类溶剂。电沉积温度范围为80~170℃，沉积电压区间为-0.6~-1.2 V（参比电极为填充有机溶液的Ag/AgCl电极）。所用基底包括玻璃基氧化铟锡（ITO）、钼与钛，阳极采用铟或石墨材料。实验采用快速搅拌方式。所有电解液体系的沉积过程均较为缓慢。薄膜的均匀性与附着性仅处于中等水平，常出现覆盖不均、开裂剥落等现象。性能最优的电解液体系为乙二醇或1,2-丙二醇基体系，所得薄膜呈金黄色，名义组成为In₂S₃₋ₓOₓ，通常在基底边缘处沉积厚度更大。当温度较低或电流较大时，有时会生成富铟的棕褐色薄膜。通过循环伏安法明确了起始电位、副反应及光活性特征，其中以乙二醇/丙酸/水混合体系制备的硫化铟薄膜表现出最强的阳极光电流，这源于其In₂S₃的n型导电特性。扫描电子显微镜（SEM）表征结果显示，金黄色薄膜具有致密的细晶粒微观结构。能量色散X射线能谱（EDX）与光电子能谱（XPS）测试数据表明，薄膜的氧含量最高可达15%。