Electronic structure of PCBM

• 作 者: 盛春荠 王鹏 沈影 李艳君 张文华 徐法强 朱俊发 来国桥 李宏年
• 机 构: Department of Physics,Zhejiang University,Key Laboratory of Organosilicon Chemistry and Material Tec
• 出 处: Chinese Physics B
• 发表日期: 2012年01期
• 关键词: backbone photoelectron butyric bonding hybridize abundant occupied parent synchr

We have studied the electronic structure of [6,6]-phenyl-C 61-butyric-acid-methyl-ester (PCBM) using synchrotron radiation photoelectron spectroscopy (PES) measurements and first-principles calculations.The PES spectrum of the entire occupied valence band is reported,which exhibits abundant spectral features from the Fermi level to ～ 24 eV binding energy.All the spectral features are broadened as compared with the cases of C 60.The reasons for the broadening are analysed by comparing the experimental data with the calculated energy levels and density of states.Special attention is paid to the analysis of the C 60 highest occupied molecular orbital (HOMO)-1 derived states,which can play a crucial role in the bonding at the interfaces of PCBM/polymer blenders or PCBM/electrodes.Besides the well-known energy level splitting of the C 60 backbone caused by the lowered symmetry,C 2p states from the side chain mix or hybridize with the molecular orbitals of parent C 60.The contribution of the O 2p states can substantially modify the PES spectrum.

We have studied the electronic structure of [6,6] -phenyl-C 61-butyric-acid-methyl-ester (PCBM) using synchrotron radiation photoelectron spectroscopy (PES) measurements and first-principles calculations.The PES spectrum of the entire occupied valence band is reported, which exhibits abundant spectral features from the Fermi level to ~ 24 eV binding energy. All of the spectral features are broadened as compared with the cases of C 60. reasons for the broadening are analyzed by comparing the experimental data with the calculated energy levels and density of states. Special attention is paid to the analysis of the C 60 most occupied molecular orbital (HOMO) -1 derived states, which can play a crucial role in the bonding at the interfaces of PCBM / polymer blenders or PCBM / electrons. Besides the well-known energy level splitting of the C 60 backbone caused by the lowered symmetry, C 2p states from the side chain mix or hybridize with the molecular orbitals of parent C 60. the contribution of t he O 2p states can substantially modify the PES spectrum.