化学学报 ›› 2016, Vol. 74 ›› Issue (12): 1003-1008.DOI: 10.6023/A16080437 上一篇    下一篇

所属专题: 聚集诱导发光

研究论文

第一性原理研究HC(NH2)2PbI3钙钛矿(三方相VS六方相)的结构及光电特性

赵兹罡, 鲁效庆, 李可, 魏淑贤, 刘学锋, 牛恺, 郭文跃   

  1. 中国石油大学(华东) 理学院 山东青岛 266580
  • 收稿日期:2016-08-26 出版日期:2016-12-15 发布日期:2016-10-20
  • 通讯作者: 鲁效庆 E-mail:luxq@upc.edu.cn
  • 基金资助:

    项目受国家自然科学基金(21303266),中央高校基本科研业务费专项资金(15CX05050A,15CX08010A和14CX02214A)和研究生创新工程项目(YCXJ2016084)资助.

First-Principles Theory Investigation on Structural and Photoelectronic Properties of Perovskites:Trigonal versus Hexagonal HC(NH2)2PbI3

Zhao Zigang, Lu Xiaoqing, Li Ke, Wei Shuxian, Liu Xuefeng, Niu Kai, Guo Wenyue   

  1. College of Science, China University of Petroleum, Qingdao 266580, China
  • Received:2016-08-26 Online:2016-12-15 Published:2016-10-20
  • Supported by:

    Project supported by the National Natural Science Foundation of China (21303266), the Fundamental Research Funds for the Central Universities (15CX05050A, 15CX08010A, and 14CX02214A), and Postgraduate's Innovation Project (YCXJ2016084).

采用第一性原理,研究三方及六方相FAPbI3(FA=HC(NH22+)钙钛矿的结构及光电特性.结果表明,FAPbI3钙钛矿由三方到六方的形变能够扭转PbI3骨架,改变Pb—I键合特性,进而改变其禁带宽度值.两种晶体均属于直接带隙半导体,三方相FAPbI3的直接带隙点位于布里渊区Z(0,0,0.5)对称点,具有较为理想的约1.50 eV的禁带宽度;六方相FAPbI3的直接带隙点位于Γ(0,0,0)对称点,具有约2.50 eV的禁带宽度.FA离子不直接参与电子跃迁过程,仅仅充当电荷供体为PbI3骨架提供超过0.7 e的电荷.相比于六方相晶体,三方相FAPbI3具有更小的载流子有效质量,吸收光谱发生了显著的红移,并且其吸收特性优于六方相FAPbI3和四方相MAPbI3(MA=CH3NH3+)钙钛矿.六方相FAPbI3比三方相晶系更稳定,FA和PbI3骨架之间的结合作用力强于MA和PbI3骨架之间的作用力.

关键词: HC(NH2)2PbI3钙钛矿, 第一性原理, 晶体形变, 光电特性, 结合能

Formamidinium lead halide perovskite FAPbI3(FA=HC(NH2)2+) has drawn wide attention as efficient photoelectronic conversion material.First-principles calculations were performed by using the Vienna ab initio simulation package (VASP) based on density functional theory.The structure configuration,electronic property,absorption spectrum,and bonding energy were analyzed to elucidate the structural and photoelectronic properties of trigonal and hexagonal FAPbI3 perovskites.Results showed that the crystal deformation from trigonal to hexagonal crystal would distort the PbI3 framework,change the covalent/ionic Pb-I bonds,and eventually alter the semiconductor bandgaps.The trigonal and hexagonal FAPbI3 perovskites are both direct-bandgap semiconductors.The direct-bandgap nature of trigonal crystal locates at Z (0,0,0.5) symmetry point with the ideal bandgap of ca.1.50 eV;the direct-bandgap nature of hexagonal crystal locates at Γ(0,0,0) symmetry point with the wide bandgap of ca.2.50 eV.For the both crystals,the main contributions to VBM (valence band maximum) are I 5p orbitals with a little overlapping of Pb 6s orbitals,and the main components of CBM (conduction band minimum) are Pb 6p orbitals.The FA cations do not directly participate into the electron transition process,just acting as charge donors to supply PbI3 framework with more than 0.7 e.There exists both covalent and ionic interactions between Pb and I ions.Compared with the hexagonal crystal,the trigonal FAPbI3 possesses smaller electron and hole effective masses.It exhibits dramatic red shifted absorption spectrum and a better absorption efficiency than hexagonal FAPbI3 and tetragonal MAPbI3(MA=CH3NH3+) perovskites.Bonding energy analyses showed that the hexagonal FAPbI3 was more stable than the trigonal crystal,and interaction between FA and PbI3 framework was stronger than that between MA and PbI3 framework.Our results could provide theoretical guidance for the experimental design and synthesis of FAPbI3 perovskite solar cells.

Key words: HC(NH2)2PbI3 perovskite, first-principles theory, crystal deformation, photoelectronic property, bonding energy