基于替位掺杂的新型铁电薄膜的光伏效应及光物理机理研究

Ferroelectrics have recently attracted attention as a candidate class of materials for use in photovoltaic devices due to its abnormal photovoltaic effect. However, the efficiency reported so far is still low. Hence it is urgent to develop ferroelectric material with narrow bandgap and strong ferroelectric property. Based on our previous work on double perovskite multiferroic oxide (Bi2NiMnO6) film, this project aims to improve the ferroelectric photovoltaic device performance from three aspects . Firstly, to fabricate ferroelectric films, tune the bandgap of double perovskite multiferroic oxides by site substitution to increase the absoption of solar spectrum, and study the crystal structure, ferroelectric and optical property and mechanism ; Secondly, to study the carrier dynamics in ferroelectric film using ultrafast pump-probe spectroscopy, reveal the effects of polarization, crystal structure, strain, thickness, and the presence of interfaces on carrier lifetimes and photophysics mechanism; Finally, to use ZnO nanostruture as elctrode to improve the charge collection efficiency.

铁电光伏电池所具有的反常光生伏特效应使其具有重要的应用前景而成为研究热点。但是目前报道的效率还较低。迫切需要寻找强铁电性的窄带隙铁电材料。本项目拟在已有的铋基双钙钛矿Bi2NiMnO6 (BNMO)铁电薄膜基础上，从三个方面来开展研究。第一，通过替位掺杂等手段调节材料带隙，制备能带合适、吸光能力强的高质量的铁电薄膜以提高对太阳能的吸收，进一步研究其结构和生长机理、铁电性能、光学性质及其微观机理；第二，采用超快泵浦探测光谱研究载流子动力学，系统研究铁电薄膜极化、晶体结构、应力、薄膜厚度、界面对载流子寿命的影响，揭示铁电薄膜中光伏效应的光物理机制；第三，利用氧化锌纳米结构电极提高载流子的收集，从而提高电池的光电转换效率。

该项目针对目前铁电光伏器件光电流低，转换效率不高的问题，制备了基于宽光谱、强吸收、强铁电性的铁电薄膜的铁电光伏器件并研究其光伏机理；研制了带隙可调的铁电薄膜，研究了铁电性能、界面效应与状态、退火温度对铁电薄膜光伏特性的影响。通过组分和层数的变化对铁电薄膜的晶体结构、能带结构、微结构和化学价态等的影响规律的机理分析，揭示了铁电光伏器件的光电转换机制，从而为开发性能可调、低成本、高效绿色环保型铁电薄膜太阳能电池提供一定的理论指导和技术支持。该项目发表SCI 收录学术论文17篇，其中项目主持人以通讯作者发表的SCI二区论文7篇，授权实用新型专利一项，发明专利1项，培养硕士生2名。已完成合同书规定的验收指标。