钙钛矿CH_3NH_3PbI_3晶体的电化学（英文）  

Electrochemistry of Perovskite CH_3NH_3PbI_3 Crystals

作　　者：杨春和[1] 唐爱伟[1] 滕枫[2] 蒋克健[3] YANG Chunhe;TANG Aiwei;TENG Feng;JIANG Kejian(Department of Chemistry,School of Science,Beijing Jiaotong University,Beijing 100044,P.R.China;Institute of Optoelectronic Technology,School of Science,Beijing Jiaotong University,Beijing 100044,P.R.China;Key Laboratory of Green Printing,Institute of Chemistry,Chinese Academy of Sciences,Beijing 100190,P.R.China)

机构地区：[1]北京交通大学理学院化学系,北京100044 [2]北京交通大学理学院光电技术研究所,北京100044 [3]中国科学院化学研究所绿色印刷院重点实验室,北京100190

出　　处：《物理化学学报》2018年第11期1197-1201,共5页Acta Physico-Chimica Sinica

基　　金：supported by the Scientific Research Fund of Beijing Jiaotong University(KSRC12006536);the National Natural Science Foundation of China(61674011,61735004)~~

摘　　要：电化学方波伏安及循环伏安测量表明,钙钛矿CH_3NH_3PbI_3晶体在有机电解质中的氧化还原过程伴随着化学降解。该化学降解源于CH_3NH_3PbI_3晶体中铅离子的还原以及碘离子的氧化。通过电化学伏安法可以测定晶体的能带。Perovskite CH3NH3PbI3 is an ionic crystal with suitable band gap and conductivity for optoelectronic applications.The sensitivity of the CH3NH3PbI3 crystal and its derivatives to chemical composition,filmforming process,and even moisture lead to difficulties in evaluating its electronic structure and redox behavior using electrochemical techniques.Nevertheless,full understanding of the electrochemical behavior of the perovskite crystal is certainly beneficial for tuning its redox properties and chemical stability,especially for device fabrication.We show that the band structure of CH3NH3PbI3 can be successfully evaluated based on electrochemical square wave voltammetry.The energy level of the bottom of the conduction band of the perovskite crystal was determined directly from the onset reduction potential with reference to the onset oxidation potential of ferrocene,and estimated to be?3.56 eV;the top of the valence band,at–5.07 eV,was determined indirectly after taking into consideration the bandgap,because the oxidation current of the iodide ions shields that corresponding to the valence band of the CH3NH3PbI3 crystal.The overlap of the oxidation currents from the iodide ions and the valence band of the crystal suggests that there are excess iodide ions in CH3NH3PbI3 not involved in the development of the valence band.In addition,the alternating current(AC)impedance spectra of CH3NH3PbI3 indicate that the iodide ions are not completely immobilized.These imply that the defects in the crystal are related to the iodide ions to a large extent.The electrochemistry of CH3NH3PbI3 in an organic electrolyte reveals its coupling degradation during the redox processes in square wave and cyclic voltammetry.The degradation reactions result from the reduction of lead ions and oxidation of iodide ions in the perovskite crystal.In electrochemical reduction,along with the reduction that occurs in the conduction band,the lead ions in the crystal are reduced to metallic lead,which introduces a phase change in the crystal,as reve

关 键 词：钙钛矿 太阳能电池 电化学 能带 氧化还原反应 

分 类 号：O646[理学—物理化学]