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New Method of Preparation of Polycrystalline Silicon Thin Films for High-Efficiency and Low-Cost Solar Cells

高效低成本太阳能电池多晶硅薄膜制备新方法

基本信息

批准号：
07458106
负责人：
NAKATO Yoshihiro
金额：
$ 4.48万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07458106/
关键词：
Polycrysalline silicon Porous silicon Ultrafine metal particle Electrodeposition Fused salt electrolyte Current oscillation Solar cell New junction 多結晶シリコン薄膜常温溶融塩振動現象

项目摘要

Research has been made for the purpose of (1) preparing polycrystalline silicon (Si) thin films by a new electrochemical method and (2) fabrication a high-efficiency and lowcost solar cell of a new type by development of a new junction suitable for use of such polycrystalline Si thin films. A LiCl-KCl eutectic melt at ca. 450ﾟC was used as an electrolyte, and silicon tetrachloride was electrochemically reduced and deposited on a single-crystal Si wafer or a polycrystalline Ni plate as the cathode (and substrate). Scanning electron micrographs and X-ray photoelectron spectroscopy showed that polycrystalline Si thin films were really deposited, but the films were inhomogeneous and deposited only near the upper edge of an electrolyte meniscus on the cathode, probably due to very low solubility of SiCl_4 in the electrolyte. This problem has been solved later by using an organic salt such as n-butylpyridinium chloride as the electrolyte. Basic studies on the mechanism of Si deposition has been made. First, the redox potential for SiCl_4 reduction was determined to be -0.5 V vs.Ag/Ag^+. Next, the mechanism of a current oscillation, found for reduction current corresponding to Si deposition was studied. It has been concluded that progress of the Si-depositing reaction changes the chemical structure of the Si surface, which alters the interfacial tension and hence the height of an electrolyte meniscus, and this causes the current oscillation. The Si surface modified with ultrafine metal particles has been studied as a new junction suitable for use of polycrystalline Si thin films. The deposition of ultrafine platinum particles not only on singlecrystal Si but also multicrystalline Si wafers showed that this method of junction formation is effectively applicable to polycrystalline Si thin films.

已经进行了研究的目的是（1）通过新的电化学方法制备多晶硅（Si）薄膜，以及（2）通过开发适合使用这种多晶硅薄膜的新结来制造新型高效且低成本的太阳能电池。 LiCl-KCl 共晶熔体温度约为 100°C。采用450℃作为电解质，四氯化硅进行电化学还原并沉积在单晶硅片或多晶镍板上作为阴极（和基板）。扫描电子显微照片和X射线光电子能谱表明，确实沉积了多晶硅薄膜，但薄膜不均匀，仅沉积在阴极电解质弯月面的上边缘附近，这可能是由于SiCl_4在电解质中的溶解度非常低。后来通过使用有机盐如氯化正丁基吡啶鎓作为电解质解决了这个问题。对Si沉积机理进行了基础研究。首先，SiCl_4 还原的氧化还原电位被确定为-0.5 V vs.Ag/Ag^+。接下来，研究了与Si沉积相对应的还原电流所发现的电流振荡的机制。得出的结论是，硅沉积反应的进展改变了硅表面的化学结构，从而改变了界面张力，从而改变了电解质弯月面的高度，从而导致了电流振荡。用超细金属颗粒修饰的硅表面已被研究作为适合使用多晶硅薄膜的新结。超细铂颗粒不仅在单晶硅上沉积，而且在多晶硅晶片上沉积表明这种结形成方法有效地适用于多晶硅薄膜。