富勒烯衍生物苯基C71-丁酸甲酯的结构和电学性质第一性原理研究

使用B3LYP/6-31G（d）方法对有机太阳电池中作为电子受体材料的富勒烯衍生物苯基C₇₁-丁酸甲酯（［70］PCBM）的同分异构体进行了计算.PCBM与C₇₀通过六元环和六元环共用的CC双键加成得到的产物是热力学控制产物；通过五元环和六元环共用的C—C键加成得到的产物则是动力学控制产物.［70］PCBM与C₇₀的第一绝热电子亲和势很接近.PCBM对前线轨道贡献很小，［70］PCBM的最高占据分子轨道和最低未占据分子轨道（LUMO）的电子云主要分布在C₇₀笼上.PCBM提升了C₇₀的LUMO能级水平，有利于提高太阳电池的光电转换效率.自然布居分析表明，PCBM与C₇₀之间没有发生显著的电荷转移.所有的性质研究表明，PCBM基团并不涉及电池光电转换过程，但在调整C₇₀能级水平提高光电转换效率中发挥了重要作用. 关键词： 71-丁酸甲酯')" href="#">苯基C₇₁-丁酸甲酯 电子受体 结合能 第一绝热电子亲和势

First principles calculations of structure and the electronic properties of fullerene derivative phenyl-C71-butyric acid methyl ester

Phenyl-C₇₁-butyric acid methyl ester （［70］PCBM） clusters are investigated by using the B3LYP method with 6-31G（d） basis set. The optimized results indicate that the addition of PCBM into the ［6，6］-junction produces a closed methanofullerene which is thermodynamically stable product; and the addition into the ［5，6］-junction results in an enlarged fullerene （an open fulleroid） which is a kinetically controlled product. The first adiabatic electron affinity for ［70］PCBM is similar to that for C₇₀. The energy gaps of ［70］PCBM are reduced compared with those of C₇₀. PCBM derivatives and show increased level of the lowest unoccupied molecular orbital of fullerenes. From the natural charge populations， it is found that adding PCBM unit onto the C₇₀ cages does not change the charge populations remarkably; attaching a PCBM has no effect on the electronic structures of C₇₀. The results of theoretical calculation suggest that PCBM is not involved in the process of photoelectric conversion but it plays a key role in adjusting the level of HOMO-LUMO for increasing photoelectric conversion efficiencies.