Preparation and Layer-by-Layer Solution Deposition of Cu(In,Ga)O₂ Nanoparticles with Conversion to Cu(In,Ga)S₂ Films

We present a method of Cu(In,Ga)S2 (CIGS) thin film formation via conversion of layer-by-layer (LbL) assembled Cu-In-Ga oxide (CIGO) nanoparticles and polyelectrolytes. CIGO nanoparticles were created via a novel flame-spray pyrolysis method using metal nitrate precursors, subsequently coated with polyallylamine (PAH), and dispersed in aqueous solution. Multilayer films were assembled by alternately dipping quartz, Si, and/or Mo substrates into a solution of either polydopamine (PDA) or polystyrenesulfonate (PSS) and then in the CIGO-PAH dispersion to fabricate films as thick as 1–2 microns. PSS/CIGO-PAH films were found to be inadequate due to weak adhesion to the Si and Mo substrates, excessive particle diffusion during sulfurization, and mechanical softness ill-suited to further processing. PDA/CIGO-PAH films, in contrast, were more mechanically robust and more tolerant of high temperature processing. After LbL deposition, films were oxidized to remove polymer and sulfurized at high temperature under flowing hydrogen sulfide to convert CIGO to CIGS. Complete film conversion from the oxide to the sulfide is confirmed by X-ray diffraction characterization.本研究提出了一种通过层层组装（layer-by-layer，简称LbL）的铜铟镓氧化物（Cu-In-Ga oxide，简称CIGO）纳米颗粒与聚电解质转化制备铜铟镓硫（Cu(In,Ga)S2，简称CIGS）薄膜的方法。CIGO纳米颗粒通过以金属硝酸盐为前驱体的新型火焰喷雾热解法制备，随后用聚烯丙基胺（polyallylamine，简称PAH）进行表面包覆，并分散于水溶液中。通过交替将石英、硅（Si）及/或钼（Mo）衬底浸渍于聚多巴胺（polydopamine，简称PDA）或聚苯乙烯磺酸盐（polystyrenesulfonate，简称PSS）溶液，随后浸入CIGO-PAH分散液的方式组装多层薄膜，最终得到厚度可达1~2微米的薄膜。研究发现，PSS/CIGO-PAH薄膜性能存在显著缺陷：与硅、钼衬底的附着力较弱，硫化过程中颗粒过度扩散，且机械强度不足，无法适配后续加工工序。与之相比，PDA/CIGO-PAH薄膜的机械稳定性更优，且可耐受高温处理流程。层层沉积完成后，将薄膜进行氧化处理以去除聚合物，随后在流动的硫化氢气氛下实施高温硫化处理，将CIGO转化为CIGS。通过X射线衍射（X-ray diffraction，简称XRD）表征，证实薄膜已完成从氧化物相向硫化物相的完全转化。