薄膜太阳能电池无镉缓冲层锌基纳米晶薄膜的机理研究及性能调控

Chemical bath deposition (CBD) is a common method for the deposition of CdS buffer layers in chalcopyrite solar cells. However, because of both environmental reasons and the fact that CdS layer with a band-gap energy of about 2.4 ~ 2.5 eV limits the level of optimum performance of the cells, especically in the short wavelengths domain, one of the major objectives in the field of CIGS technology remains the development and implementation in the production line of Cd-free alternative buffer layers. Besides, the wet solution method to prepare CdS buffer layers also increases the cost in production of thin films solar cells dealing with Cd-content wastewater. Therefore, it has attracted more and more attention in the whole world to explore novel buffer layer materials replacing the CdS. In a chalcopyrite cell, the environmentally friendly material Zn-based thin films can well satisfy the requires of buffer layers in CIGS thin films devices. As the buffer layer, Zn-based film not only is the eco-friendly material, but also possesses the larger energy gap which can match well the absorber layer. Based on the prospects for mass-production of CIGS thin films solar cell, this project put forward the method suitable to produce low-cost, large area buffer layer thin films: physical vapro deposition of Zn-based buffer layers thin films. We will focus these points: investigate the effects on Zn-based thin film properties by the different parameters in the preparing process; establish the relationships between the buffer layer and cells properties; explore the interface issues between buffer layer and absorber layer, buffer layer and window layer; open out the relationships between interface properties and the whole cells performancea and so on. Moreover, this project offers one whole set of dry vacuum process to prepare the CIGS thin films solar cell which is valuable in practical application.

CIGS薄膜太阳电池缓冲层通常是采用化学浴沉积法(CBD)制备的CdS薄膜，这与新型能源材料追求的高效、低成本以及环保的特点不符，湿式溶液生长缓冲层CdS不仅存在潜在毒害，而且在生长过程中必须引入高碱性废液处理，势必增加制造成本，因此开展新型缓冲层替代CdS膜的研究成为国内外相关研究的热点。申请人基于采用比CdS带隙更宽的材料、透过由CdS膜吸收的短波(520 nm以下)、增加CIGS吸收层光电转换产生的光电流这一特点，提出以环保型材料Zn基纳米晶薄膜为缓冲层，重点研究其光学特性、导电性、载流子输运机制以及与吸收层、窗口层之间存在的界面作用机理，研究Zn在吸收层中的扩散机制，降低缺陷复合，提高光量子效率，采用物理气相沉积实现Zn基纳米晶缓冲层薄膜的低温可控干法制备，并应用到CIGS薄膜电池中对其性能进行研究，建立缓冲层薄膜的性能变化、有效界面以及载流子输运特征对电池性能的影响规律。

铜铟镓硒(CIGS)太阳能电池是一种新型环保的电池，随着环境污染、雾霾问题的加剧，铜铟镓硒薄膜太阳能电池关键技术的研究不断被刷新，目前，CIGS薄膜太阳电池缓冲层通常是采用化学浴沉积法(CBD)制备的CdS薄膜，这与新型能源材料追求的高效、低成本以及环保的特点不符，湿式溶液生长缓冲层CdS不仅存在潜在毒害，而且在生长过程中必须引入高碱性废液处理，势必增加制造成本，本项目针对铜铟镓硒薄膜太阳能电池中的缓冲层部分进行创新性研究，提出无镉薄膜缓冲层的重要研究价值，基于当前铜铟镓硒薄膜太阳能电池中存在的CdS薄膜的问题，创新性地建立无镉ZnS缓冲层薄膜及其掺杂体系对铜铟镓硒薄膜太阳能电池关键性能的影响机制，主要研究内容包括以下三点：一、采用全干法制备缓冲层薄膜，与铜铟镓硒太阳能电池的关键制备技术相结合，以制备出叠层结构glass/Mo/CIGS/Zn(S、O)/i-ZnO/ZnO:Al的薄膜太阳能电池，并结合ZnS薄膜的光学性能进行参数优化，以提高太阳能电池的转换效率高。二、研究了Zn基化合物薄膜作为缓冲层的器件性能研究，可以拓宽电池对太阳光谱的响应范围；三、着重研究了缓冲层性能以及对整个电池器件的作用机理的影响进行了研究，并建立了缓冲层薄膜对CIGS薄膜太阳能电池的影响机制，通过对比优化选取环保低成本的适合工业化生产的制备工艺来制备薄膜，系统研究缓冲层的成分控制、温度影响、厚度变化、微观结构、缺陷状态、带隙匹配、表面界面组态以及载流子传输机制对电池特性的影响。本项目的研究为新能源材料在清洁能源领域的应用提供了实验和理论借鉴！取得的重要研究成果有获得2项授权发明专利，以第一作者或通讯作者发表SCI论文7篇，以合作者身份发表SCI论文数篇，协助指导本科生实习2名，协助培养研究生3名。