三维纳米阵列铁电光伏电池的制备与研究

Ferroelectric materials exhibiting abnormal photovoltaic effect is one of the foci of photovoltaic research. Unlike the traditional pn junction, ferroelectric photovoltaic is a kind of bulk effect, in which photogenerated carriers can be separated in the whole material, the photogenerated voltage is not limited by the band gap and the built-in electric field can approach to 1000 ~ 100000 V/cm. Theoretically, this comes to a high photo-to-electric conversion efficiency. However, due to its low photogenerated current, the photo-to-electric conversion efficiency of ferroelectric thin film is not high enough. In view of this problem and improving the photo-to-electric conversion efficiency of ferroelectric materials, three-dimensional nano-array ferroelectric photovoltaic devices by anodic aluminum oxide will be built firstly in this project, and then the ferroelectric/electrode interface will be improved. Based on the advantages of nanostructures ,such as large surface area, light trapping effect, shorting carrier diffusion length, etc., combined with the interface modification (the interface Schottky barrier is eliminated), the utilization efficiency of visible light will be improved and the separation of photoelectrons from vacancies will be promoted. The law of enhancing the efficiency of photoelectric conversion of ferroelectric materials will be explored as well as its physical processes and mechanisms to develop a high efficient ferroelectric photovoltaic cells.

铁电材料由于具有反常光伏效应（abnormal photovoltaic effect）而备受关注，与传统的pn结所不同的是，铁电光伏是一种体效应，光生载流子能在整个材料中被分离开来，光生电压不受禁带宽度的限制，內建电场达到1000 ~ 100000 V/cm，理论上具有较高的光电转换效率。然而，由于其光生电流较低，以至铁电薄膜的光电转换效率还不够高。针对这个问题，本项目以提高铁电材料光电转换效率为目标，率先提出利用阳极氧化铝模板构筑三维纳米阵列的铁电光伏器件，并对铁电/电极界面进行修饰。基于纳米结构的优势（如比表面积大、陷光效应、缩短载流子扩散长度等），结合界面修饰，消除界面肖特基势垒，来提高可见光利用率，并实现光生电子/空穴的有效分离，探索提升铁电材料光电转换效率的规律，分析其物理过程和机理，研制出高效的铁电光伏电池。

铁电材料由于具有反常光伏效应而备受关注，与传统的pn结所不同的是，铁电光伏是一种体效应，形成的內建电场贯穿整个材料，能够达到1000 ~ 100000 V/cm，光生电压不受禁带宽度的限制，理论上具有较高的电荷分离效率。但是其光生电流较低，以至铁基器件的效率很低。因此，本项目提出利用纳米结构的优势（如比表面积大、陷光效应、缩短载流子扩散长度等），结合界面修饰，来提高铁电材料的光电转换效率。本项目主要研究内容包括铁电材料（BFO和PZT）三维纳米结构的制备，界面调控（包括纳米颗粒修饰、异质结构建等），双极性光电流的机理探究，铁电材料极性电场的应用研究等。研究结果发现，相对于平面结构的薄膜来说，三维纳米结构的铁电材料光电流得到有效的提高（5倍，0.6 V vs RHE）；PZT能够实现双极性光电流（阳极电流和阴极电流）；铁电材料极化引起的内建电场能有效分离电子空穴对，使TiO2等材料的光电化学性能得到大幅提升，有助于铁电的应用发展。