钙钛矿光伏器件中异常迟滞现象的扫描探针研究

项目名称： 钙钛矿光伏器件中异常迟滞现象的扫描探针研究

项目编号： No.11504408

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 数理科学和化学

项目作者： 陈琪

作者单位： 中国科学院苏州纳米技术与纳米仿生研究所

项目金额： 24万元

中文摘要： 光伏器件在性能测试过程中常会表现出电流-电压曲线随电压扫描方向、扫描速度等参数的选择而变化的迟滞现象，影响测得的器件光电转换效率的准确性。这种迟滞现象源于不同扫描参数下，载流子产生、分离、复合、输运和收集等微观过程的变化。但是对于目前光伏器件中的明星材料有机金属钙钛矿而言，其表现出的迟滞现象难以用解释传统光伏器件的机理来理解。为了解析钙钛矿器件异常迟滞现象的成因，我们需要原位研究钙钛矿中光生载流子的输运性质，获得不同扫描参数下载流子微观运动过程的变化规律。为此，我们提出利用已建立的器件截面制备技术，将扫描开尔文探针显微镜和自主开发的介电力显微镜协同应用于载流子微观运动过程与迟滞现象关系的研究中，理解钙钛矿极化和表界面缺陷态等关键科学问题对迟滞现象的影响，从而有效抑制迟滞现象并为器件性能优化提供依据。

中文关键词： 扫描探针显微镜；钙钛矿；异常迟滞现象；铁电极化；表界面

英文摘要： Hysteresis is an perennial problem in photovoltaic devices, which manifests as different shapes of current-voltage curves when voltage sweeping parameters, e.g. scanning direction, scan rate et al, has been changed, thus hinders the measurement of true power conversion efficiency (PCE). Hysteresis is originated from the change of elementary photovoltaic processes, such as the generation, separation, transport, recombination and collection of charge carriers, when different scan parameters are used. However, it is naive to explain hysteresis of the state-of-the-art organometallic perovskite photovoltaic devices based on mechanism of that in traditional photovoltaic devices. To explore the reasons of anomalous hysteresis in perovskite devices, it is necessary to investigate the transport properties of photogenerated carriers in situ, and understand the behaviour of carriers with different scan parameters. Thus, based on our previous work, we proposed synergetic application of scanning Kelvin probe microscopy (SKPM) and dielectric force microscopy (DFM) in cross-sectional organometallic perovskite devices, to investigate the relationship between behavior of carriers and hysteresis. Furthermore, understanding this relationship is important to explore the mechanism of hysteresis and its connection with perovskite polarization and surface/interface defect states, which is helpful to resolve hysteresis and further improve device performance.

英文关键词： scanning probe microscopy;perovskite;anomolous hysteresis;ferroelectric polrization;surface/interface