BiFeO3铁电薄膜光伏特性及机制研究

Ferroelectric material BiFeO3 has a narrow bandgap（2.6-2.8eV）and it has outstanding photovoltaic property under visible light. BiFeO3 as a kind of lead-free ferroelectric materials perfoemance both ferroelectric and ferromagnetic properties at room temperature, it is expected to become the new photovoltaic cell or other optoelectronic devices.But for the key factors influencing the photovoltaic effect and mechanism of BiFeO3 thin films, there is still no consensus. Pure perovskite BiFeO3 thin film in this project is prepared by sol-gel method with highly directional. Electrode type, annealing atmosphere and sol-gel process will be explored to establish the growth model of BiFeO3 thin films.We will test the electrical and optical properties of BiFeO3 thin films. We will find out the type, concentration and transport of the carrier from the ferroelectricity, interphase,size and space-charge effect of BiFeO3 thin films.The separate and transport model of carrier in domain and electric domain wall will be established. It not only has the innovation in technology, but also for future optoelectronic devices based on energy preparation materials.

铁电材料BiFeO3具有较窄的禁带宽度（2.6-2.8eV），在可见光范围内具有显著的光伏效应，BiFeO3作为一种无铅铁电材料，室温下同时具有铁电、铁磁性能，有望成为新型光伏电池或其他新型光电子器件。但对于影响BiFeO3薄膜光伏效应的关键因素及作用机理，仍然没有达成共识。本项目拟采用溶胶-凝胶法制备高度定向的纯钙钛矿BiFeO3致密薄膜，考察电极类型、退火气氛以及溶胶-凝胶的工艺参数对BiFeO3薄膜物相和形貌的影响，探讨并建立 BiFeO3薄膜的生长模型。测试BiFeO3薄膜的电学、光学性能，从铁电性、界面、尺度及空间电荷效应对BiFeO3薄膜光伏特性影响因素的角度出发，弄清楚载流子种类、浓度及输运的动态过程，并建立载流子在电畴内部以及畴壁的分离和输运模型。这不仅在技术上具有创新意义，而且可以为未来的光电子能源器件准备和铺垫材料方面的基础。

BiFeO3(BFO)是一种常温下具有铁电性、铁磁性的多铁材料，由于其具有较小的禁带宽度，故在钙钛矿太阳能电池领域中具有较为广阔的应用前景。但是，BFO薄膜在可见光照射下表现出较低的转换效率，其自身存在较大的漏电流缺陷和载流子复合是造成这种现象的主要原因。因此，对BFO薄膜的改性成为了拓展其应用的关键环节。本项目拟采用溶胶-凝胶法制备BFO前驱体溶液，通过工艺改进(如退火方式、基底选择与匀胶制度、退火保温时长、旋涂层数)及石墨烯复合的方法制备光伏性能优异的BFO基薄膜；利用各种现代分析测试手段，探讨影响薄膜光伏性能的因素，研究高效可见光吸收作用机理。实验发现，相比于纯相BFO薄膜(开路电压VOC为0.42V)，石墨烯复合构型薄膜样品VOC提高至0.8V，光伏性能得到明显改善。