Development of a Soft Process for CdTe Solar Cell using Photo-assisted Electrodeposition

利用光辅助电镀技术开发 CdTe 太阳能电池软工艺

基本信息

批准号：
14350399
负责人：
HIRATO Tetsuji
金额：
$ 9.92万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

To develop a new soft process for CdTe thin layer solar cell, photo-assisted electrodeposition of CdTe from ammoniacal basic electrolytes was investigated. The electrical properties of polycrystalline CdTe layers electrodeposited were examined by resistivity and Hall effect measurement, As-deposited CdTe layers were found to be p-type with resistivity of 10^7-10^9Ω cm, carrier density of 10^9-10^<11> cm^<-3>, and mobility ca. 1 cm^2 V^<-1> s^<-1>. This high resistivity of CdTe layer from basic baths probably leads to low-efficiency solar cells. The microstructures of CdTe layers electrodeposited from basic electrolytes were investigated by transmission electron microscopy and compared with those from a conventional acidic sulfate electrolyte. As^- deposited CdTe layers from a basic electrolyte were composed of randomly oriented crystallites with a grain size of ca.10 nm, while those from an acidic electrolyte consisted of defective columnar grains with a <111> preferred growth orientation. Each of the columnar has a diameter of of ca.150 nm. The small grain size of the polycrystalline CdTe deposits from the basic electrolyte suggests that nucleation of new grains occurs frequently during electrodeposition. By annealing at 573 K for 1 h in an Ar atmosphere, CdTe grains from the basic electrolyte grew by about a factor of four, but at the same time, nano-voids were formed at the grain boundaries. In contrast, CdTe grains from the acidic electrolyte did not grow by annealing the same conditions. Since a large grain size is desirable for CdTe layers to be used in high-efficiency solar cells, it is important to control the nucleation of new grains during electrodeposition and the grain growth of CdTe deposits by annealing.

为了开发一种新的软工艺来用于CDTE薄层太阳能电池，研究了来自氨基基碱性电解质的CDTE的光辅助电沉积。通过抗性和HALL效应测量测量了多晶CDTE层电沉积的电气特性，发现被抑制的CDTE层是p型，电阻为10^7-10^9Ωcm，载体密度为10^9-10^9-10^<11> cm^<11 cm^<-3>，以及Mobsilition Ca。 1 cm^2 v^<-1> s^<-1>。 CDTE层从碱性浴中的高电阻可能导致低效率太阳能电池。通过透射电子显微镜研究了来自基本电解质的电沉积的CDTE层的微观结构，并将其与常规酸性硫酸盐电解质的微观结构进行了比较。 As^ - 基本电解质的沉积CDTE层由晶粒大小为Ca.10 nm的随机定向的结晶岩组成，而来自酸性电解质的晶粒层由<111> <111>首选生长方向的有缺陷的柱状晶粒组成。每个柱状的直径为150 nm。来自基本电解质的多晶CDTE沉积物的小晶粒大小表明新谷物的成核在电沉积过程中经常发生。通过在AR气氛中在573 K处退火1小时，碱性电解质的CDTE晶粒生长约四倍，但同时，在晶界形成了纳米粒。相反，通过退火相同的条件，来自酸性电解质的CDTE晶粒不会生长。由于希望将CDTE层用于高效太阳能电池中，因此需要大晶粒尺寸，因此在电沉积过程中控制新晶粒的成核和通过退火来控制CDTE沉积物的晶粒生长非常重要。