P(VDF-TrFE)/MAPbBr3光控电极化效应及多场耦合

Photoferroelectric materials possess both ferroelectricity and light absorption properties, they are quite promising for the applications in the fields of multi-energy conversion, information storage and multifunctional sensing. At present, most of the research focus on the controlling of photovoltaic effect via ferroelectric properties, while, little is known about how the light influences the ferroelectricity. Compared with ferroelectric oxides, polymers show better photostability, chemical stability, and easy processability. However, the polarization of polymer is still low and new approach is necessary for breakthrough. Here, we design the P(VDF-TrFE)/MAPbBr3 composites based on the idea that the product property between the photostriction effect from MAPbBr3 and piezoelectric effect from P(VDF-TrFE) would result in giant ferroelectric polarization induced by light. The optical and electrical properties, light induced polarization effect and their responses to the external fields would be studied comprehensively. The intrinsic connection between the micro/macrostructures, the physical and chemical properties of the constituents around interfaces and the light induced polarization effect will be established. Moreover, the coupling effect among photon, lattice and charge in the photoferroelectric composites will be revealed. The studies shall provide physical fundamentals for developing new multifunctional optoelectronic devices, sensors and energy harvesting devices.

光敏铁电材料同时具有铁电性和光吸收相关性质，在多源能源转化、信息存储和多功能传感领域有广泛的应用前景。当前研究集中在如何调节铁电材料的物理化学性质实现光伏性能的优化，而光对铁电性的影响却缺乏认知。铁电聚合物具有比氧化物更稳定的光学、化学性质和易加工性，但其电极化强度低。本项目通过构建P(VDF-TrFE)/MAPbBr3复合体系，巧妙的利用光电金属卤化物钙钛矿的光致伸缩效应与铁电聚合物的压电效应相耦合，产生全新的光致电极化‘积性能’，实现巨光控电极化效应。系统研究复合材料的光、电特性，光控电极化效应及外场的调控作用，获得多场作用下复合材料光、电响应规律，建立复合材料的微/介观结构、两相界面物理化学性质与光控电极化效应内在关联，揭示复合光敏铁电材料中光子-晶格-电荷耦合机制，为发展新型多功能光电子器件、传感器件以及能量收集装置提供理论依据。

随着物联网深化发展，对传感器的微型化、柔性化、智能化、集成化提出更高层次需求。具有多场耦合效应的功能材料，利用其外场响应和涉及的能量转换原理，可构筑多功能器件实现传感与供能功能的高度融合。光敏铁电材料同时具有铁电性和光吸收相关性质，然而两种功能是否相互耦合、能否实现多场调控，特别是光如何调控电极化，缺乏深入认知。本项目通过构建MAPbBr3/P(VDF-TrFE)复合体系，巧妙利用卤素钙钛矿中光子-晶格耦合与铁电聚合物的晶格-电荷耦合，通过两相界面应力建立光子-晶格-电荷耦合作用，产生全新的光致电极化‘积性能’，实现光控电极化效应。通过研究PVDF基纳米复合材料制备工艺，发展了聚合物限域卤素钙钛矿原位生长方法，制备出一类兼具强极化、优异发光与机械柔性的新颖光敏铁电纳米复合材料；通过系统表征测试复合材料的组成含量、物相、显微结构，光学、电极化、力学性能，建立结构-性能关联；通过研究电场极化对复合材料结构、光学性质影响，光照前后复合材料力电耦合效应变化，分析并关联两种功能相互影响的过程与结果，提出了光-力-电多场耦合机制：光激发钙钛矿产生激子，电子和空穴由铁电聚合物内建电场分离并被偶极束缚，从而增加净电荷、提高极化强度。针对研究过程中发现的钙钛矿/PVDF纳米复合材料极化异常增强现象，深入开展增强原理研究。通过高分辨钙钛矿原子结构表征、微观压力电响应原位实验、DFT结合相场模拟计算，阐明了电场诱导钙钛矿产生Frenkel缺陷对，复合材料界面的交换耦合作用稳定缺陷对偶极，从而贡献异常增强的宏观铁电极化。利用钙钛矿/PVDF纳米复合膜优异的机电耦合效应，开发出压力传感电子皮肤应用于人体体征监测，具有灵敏准确、稳定性好等优势。本项目的研究结果不但为开发新型多功能光电子器件提供了理论依据，也为推动基于多场耦合功能材料的传感器件在物理网中应用提供了实验基础。