硫系薄膜中体相异质结网络的晶化方法构筑及其光伏特性研究

The construction of bulk heterojunction networks in the solar cells provides an important way to develop low cost and high efficiency solar cells. In this proposal, bulk heterojunction networks are supposed to be spontaneously constructed in Sb-Ge-Se(S)-CuI chalcogenide glassy thin films by controllable crystallization. This technique is expected to reduce the structural defects which typically exist in the heterojunction networks fabricated by phase-by-phase deposition, consequently increasing the separation and transport ability of charge carriers and improving the photoelectric conversion efficiency. Aiming at the controllable fabrication of bulk heterojunction networks in crystallized films, and for clarifying the relationship between their structure and photovoltaic properties, a comprehensive characterization of the dynamic crystallization process will be carried out in the thin films with different compositions, so that the underlying causes of the formation of a particular morphology under certain process condition can be clarified, and the rule for building heterojunction networks by crystallization can be mastered. Meanwhile, solar cells based on the crystallization-formed heterojunction networks will be designed and fabricated. Sequentially, by combining the studies on the energy band structure, the carrier transport characteristics and the device performance, the relationship between the morphology and the photovoltaic properties of the heterojunction network can be clarified. This study is promising to provide a new way to construct bulk heterojunction networks through crystallization of glassy thin films, and also provides a theoretical basis for the generalization of this synthesis technique in other material systems.

在薄膜太阳能电池中构筑体相异质结网络结构是研制廉价、高效光伏电池的重要途径。本项目拟通过Sb-Ge-Se(S)-CuI硫系玻璃薄膜的可控析晶，在薄膜内部自发构建出体相异质结网络，以改善目前逐相沉积方法制备的异质结网络中结构缺陷的问题，增强载流子分离与输运能力，有效提高光电转化效率。为解决晶化薄膜中体相异质结网络的可控构筑及其组织形貌与光伏特性关系等问题，本项目拟通过综合表征不同成分薄膜的析晶动态过程，阐明各晶化工艺条件下特定组织形貌形成的内在原因，从而掌握体相异质结网络的构筑规律。同时，设计合理的器件结构，将晶化获得的异质结网络应用于光伏电池；结合能带结构、载流子输运特性的研究与器件关键指标的表征，阐明异质结网络组织形貌与光伏特性关系。本项目研究有望提供一种通过玻璃薄膜的晶化处理构筑体相异质结网络的新思路，并为该手段在其他材料体系中的推广提供理论基础。

在薄膜太阳电池中构筑体相异质结网络结构是研制廉价、高效光伏电池的重要途径之一。本项目针对一种新型材料——硫系光电玻璃陶瓷中的体相异质结网络的形成机制及其光电机理开展了系统研究，探索了通过可控晶化在光电玻璃陶瓷薄膜内部构筑体异质结网络的工艺，在此基础上进一步对基于光电玻璃陶瓷薄膜的纳米结构太阳能电池原型器件的设计与制备开展研究。项目执行期间，实现了对硫系光电玻璃陶瓷中微观结构形成过程的深入认识，阐明了材料内部形成体相异质结网络的动力学条件和热力学条件；在脉冲激光沉积制备的基质玻璃薄膜中，实现了类似块体材料的体相异质结网络的构筑，并指明薄膜沉积以及热处理过程中，保持成分与最佳组分一致对构筑完整体相异质结网络的重要性；在建立光电玻璃陶瓷的光电过程机理模型的基础上，采取打破器件结构对称性的思路，设计并成功制作了以光电玻璃陶瓷薄膜为活性层的纳米结构太阳能电池。上述研究成果不仅提供了一种通过非晶薄膜的晶化处理构筑体相异质结网络、进而自上而下制备纳米结构太阳能电池的新思路，同时对寻找其他光电玻璃陶瓷材料体系也具有一定的指导意义。