KNbO3-BaNi1/2Nb1/2O3铁电纳米线阵列的可控制备及其光伏性能研究

The development of high performance photovoltaic materials is of great significance to improve the efficiency of solar cells. Above-bandgap voltages can be produced from ferroelectric due to their unique photovoltaic effect, however, the efficiency of photoelectric conversion is limited by the low visible absorption and the weak photo-generated current. Aim to the issues above, this project intends to prepare ferroelectric [KNbO3]1-x[BaNi1/2Nb1/2O3]x (KBNNO) nanowire arrays on a transparent conductive substrate to serve as photovoltaic cells derived by sunlight. Firstly, The growth mechanism of KBNNO nanowires by hydrothermal method will be investigated to realize the controllable growth of the morphology and orientation of KBNNO nanowires. The influences of components, morphology and orientation of the KBNNO on light absorption and electrons transport will be investigated. Secondly, The domains structures of the nanowires, along with the change of components and the orientation will be analyzed to explore the role of law concerning the infect of polarization potential on light carriers separation and transport. The physical mechanism of photoelectric conversion efficiency, photovoltage and photocurrent derived from polarization of KBNNO nanowires will be revealed. Finally, photovoltaic materials based on ferroelectric nanowires with wide range of visible light spectral, high photovoltage and improved photoelectric conversion efficiency will be prepared. It is of important theoretical and practical significance for the successful implementation of this project to develop a new type of ferroelectric nanowires photovoltaic materials and promote the development of solar energy battery components.

铁电材料具有独特的光伏效应，可产生高于其禁带宽度的光生电压，但过窄的可见光谱吸收范围和较低的光生电流制约了材料的光电转换效率。针对上述问题，本项目拟采用水热法制备单晶[KNbO3]1-x[BaNi1/2Nb1/2O3]x(KBNNO)铁电纳米线阵列，通过优化材料的光吸收和电输运性能实现高效光电能量转换。首先研究KBNNO纳米线阵列的可控制备技术，分析组分、形貌和结构对材料带隙宽度的影响规律，实现铁电纳米线阵列可见光吸收性能的调控。其次，分析KBNNO纳米线的尺寸和取向对材料的畴结构的影响规律，探索光生载流子的分离和输运与纳米线畴结构的关联性，揭示KBNNO纳米线的极化行为对光伏特性的影响机理。最终，获得可见光谱响应范围宽且光电转换效率高的铁电光伏材料。本项目的顺利实施对研制新型铁电纳米线光伏材料，促进高性能太阳能电池的开发与应用具有重要的理论和实际意义。

本项目针对钙钛矿铁电材料较窄的可见光谱吸收范围和较低太阳光利用率等问题，采用B位Ni掺杂部分取代的手段，实现钙钛矿铁电材料的带隙调控的研究目的，并以TiO2纳米棒阵列为电子传输介质，进而研究铁电负载TiO2复合薄膜在可见光下的光电转换，光电化学行为及其光催化性能。本项目研究的主要内容包括：（1）Ni:KNbO3与KNbO3-Ba(Ni,Nb)O3 纳米粉体的制备及其光吸收性能的研究；（2）Ba(Ni1/3Nb2/3)O3（BNN）的电子结构的第一性原理方法计算，并对其本征光学性能的分析和预测；（3）Pb(Ti,Ni)O3/TiO2纳米棒阵列复合薄膜的制备及其光电化学性能研究；（4）BiFeO3/TiO2纳米棒阵列复合薄膜的制备及其光电化学性能和光催化性能的研究。获得了PTN/TiO2复合薄膜的开路电压1.3V，短路电流0.4mA/cm2，光电转换效率2.6%。此外，这类铁电材料负载TiO2的复合结构在其他光学和光电化学器件中也表现出潜在的应用前景。