CH_(3)NH_(3)多聚体的形成对有机-无机杂化钙钛矿太阳能电池性能的影响  

Effects of CH_(3)NH_(3) polymer formation on performance of organic-inorganic hybrid perovskite solar cell

作　　者：张翱 张春秀 张春梅 田益民 闫君 孟涛 Zhang Ao;Zhang Chun-Xiu;Zhang Chun-Mei;Tian Yi-Min;Yan Jun;Meng Tao(Department of Science,Beijing Institute of Graphic Communication,Beijing 102600,China;Institute of Applied Micro-Nano Materials,School of Science,Beijing Jiaotong University,Beijing 100044,China)

机构地区：[1]北京印刷学院基础部,北京102600 [2]北京交通大学理学院,微纳材料及应用研究所,北京100044

出　　处：《物理学报》2021年第16期356-362,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11605012);国家自然科学基金青年科学基金(批准号:51802014)资助的课题;北京市教委科研计划(批准号:KM202010015008)。

摘　　要：采用第一性原理在MP2/aug-cc-PVTZ水平下优化得到CH_(3)NH_(3)多聚体的几何构型,发现多聚体中CH_(3)NH_(3)沿C-N轴取向,多聚体随着CH_(3)NH_(3)数量增加有收缩趋势,这有利于无机框架的结构稳定,多聚体的总偶极矩随着CH_(3)NH_(3)数量线性增加,这导致了CH_(3)NH_(3)PbI_(3)异质结的强极化.CH_(3)NH_(3)多聚体中未配对电子分布在每个CH_(3)NH_(3)的NH_(3-)端,轨道能量在-4.4—-3.2 eV之间.计算静电势矢量场发现CH_(3)NH_(3)~+具有强亲电性,NH_(3-)端比CH_(3-)端有更强的亲电性,CH_(3)NH_(3)单体和CH_(3)NH_(3)多聚体具有弱亲电性和亲核性,CH_(3)NH_(3)多聚体的形成有效地减少CH_(3)NH_(3)与无机[PbI_(3)]-框架之间的非谐振声子振动模式,这有利于提高CH_(3)NH_(3)PbI_(3)异质结中载流子传输.电场作用下CH_(3)NH_(3)五聚体中未配对电子通过量子跃迁机制沿着C-N轴发生转移,施加不同方向电场电子的转移效率是不一样的,转移电子数量随着电场强度增加而增加,通过这样的跃迁机制在外电场作用下电子很容易注入CH_(3)NH_(3)PbI_(3)形成CH_(3)NH_(3)多聚体.这些计算结果将有助于更深刻地理解有机-无机杂化钙钛矿太阳能电池高光电转换效率的根源.CH_(3)NH_(3)PbI_(3) is one of the most promising candidates for high-performance hybrid organic-inorganic perovskite solar cells.The CH_(3)NH_(3)PbI_(3) single crystal and poly crystalline thin film exhibit the unique features of long carrier lifetimes and diffusion lengths,however,their carrier mobilities are in fact rather modest in a range from 1 cm^(2)·V^(-1)·s^(-1) to 100 cm^(2)·V^(-1)·s^(-1).Experimentally,the temperature dependence of mobility is described as T-1.3 to T-1.6 due to the acoustic phonon scattering.To be sure,the rotating CH_(3)NH_(3) cations are disadvantageous to the carrier transport and performance for CH_(3)NH_(3)PbI_(3) solar cells.The effect of the rotating CH_(3)NH_(3) cations on high-performance CH_(3)NH_(3)PbI_(3) solar cells remains an open question.The Gaussian 09 software has been utilized to optimize the geometrical structures of CH_(3)NH_(3) dimer,trimer,tetramer,and pentamer in isolated state at the MP2 level with using the cc-PVTZ basis set.For CH_(3)NH_(3) polymer,the mean distance between two centroids of neighboring CH_(3)NH_(3) decreasing with the number of CH_(3)NH_(3) is slightly smaller than the lattice constant 6.28 A of tetragonal CH_(3)NH_(3)PbI_(3),which is advantageous to structural stability and higher structural order of inorganic[PbI_(3)]-framework.It signifies that the long range order of electrically neutral CH_(3)NH_(3) is easily formed for room-temperature CH_(3)NH_(3)PbI_(3).The total dipole moment linearly increases with the number of CH_(3)NH_(3) for CH_(3)NH_(3) polymer,and attains a large value 19.7 Debye for CH_(3)NH_(3) pentamer,which may be the origin of strong polarization in CH_(3)NH_(3)PbI_(3) heterojunction.The molecular orbitals of five unpaired electrons for CH_(3)NH_(3) pentamer are distributed around NH3-sides of five different CH_(3)NH_(3) pentamers respectively,and these orbital energies are in a range from-4.4 eV to-3.2 eV.The unpaired electrons in CH_(3)NH_(3) polymer have an electrostatic attraction on the CH3-side of neighboring CH_

关 键 词：有机-无机杂化钙钛矿 太阳能电池 第一性原理计算 

分 类 号：TM914.4[电气工程—电力电子与电力传动] TB34[一般工业技术—材料科学与工程]