有机钙钛矿材料的铁电性及铁电极化对光伏调控研究

Successively broken records on the photoelectric conversion efficiency of the solar cell based on organic perovskite material have been made, which aroused the people to study on the basic nature of the CH3NH3PbI3 (MAPbI3).The latest research shows that many properties of MAPbI3 material such as the ambipolar self-doping, high dielectric constant and current-voltage hysteresis may.be related to the potential ferroelectric properties on MAPbI3 material. In this project, we will choose the MA PbI3 as the object and systematically investigate the potential ferroelectric property and the regulation of ferroelectric polarization on the photovoltaic control by performing first principles calculations and Monte Carlo methods.The main research contents including: i) Constructing MAPbI3.system with different orientation of MA+ configuration, and study its structural stability, polarization and ferroelectric phase transition temperature. ii) Under the action of stress or electric field, studying on the MA+ alignment and the structural stability of the MAPbI3 materials and trying to find a method to realize the potential ferroelectric polarization of MAPbI3 material. iii) Investigation on the regulation of ferroelectric polarization on the photovoltaic control. By constructing the interface configuration of the MAPbI3 material layer and the TiO2 layer, to study the effect of MAPbI3 polarization layer on the separation and transport properties of photo electron and hole, to explore its physical mechanism and provide some theoretical reference for the experimental and practical application.

基于有机钙钛矿材料的太阳能电池的光电转化效率不断刷新。激起人们对CH3NH3PbI3 (MAPbI3)材料的基本性质的研究热潮，最新研究表明MAPbI3 材料很多性质如双极自掺杂性、高介电常数等性质可能与其潜在铁电性有关。本项目将采用第一性原理计算和蒙特卡洛模拟相结合的方法，系统研究MAPbI3 材料潜在的铁电性及其铁电极化对光伏调控的微观机理。主要研究内容包括：i) 构建MA+离子具有不同取向的MAPbI3 构型，研究其结构稳定性、极化和铁电相变温度。ii)在应力、电场作用下，研究MAPbI3中的MA+取向排列及结构稳定性，寻找实现MAPbI3 材料铁电极化的方法。iii) 研究铁电极化对光伏调控的微观机理。通过构建MAPbI3 和TiO2 材料的界面构型，研究MAPbI3 层极化对光生电子-空穴的分离以及输运特性等的调控作用。探究其物理机理为实验和实际应用提供理论一定的参考。

有机钙钛矿材料和TiO2材料都是很好的光电材料，在光催化、太阳能电池等方面有着重要的应用价值，本项目对不同掺杂构型的机钙钛矿材料和TiO2材料的磁性、铁电以及光学性质进行了深入研究，此外对用光子晶体构建的多种滤波器的滤波调控性能进行了理论研究。（1）采用基本结构建模和第一性原理计算相结合的方法，通过对有机钙钛矿材料CH3NH3PbI3 (MAPbI3)不同极化构型和掺杂构型研究，从理论上获得结构稳定性高、高光伏转换效率有机钙钛矿材料构型。考虑在不同应力作用下，计算上述MAPbI3极化构型的稳定结构所对应的能量、铁电极化变化情况,寻找通过应力作用实现MAPbI3材料潜在铁电极化的可行性方法。（2）研究不同的V掺杂浓度和四种不同的双V原子掺杂金红石型TiO2的电子结构，磁学性质和光学特性；研究多种补偿共掺TiO2的电子结构和光学特性，寻找掺杂提高TiO2的可见光吸收方案。（3）利用光子晶体设计多种滤波器，用特征矩阵法和紧束缚理论研究了各种滤波器的光学传输等特性。