Aggregates of PCBM molecules: A computational study

作者：Kaiser Alexander; Probst Michael; Stretz Holly A; Hagelberg Frank^*

来源：International Journal of Mass Spectrometry, 2014, 365: 225-231.

DOI：10.1016/j.ijms.2014.01.019

• PCBM
• Organic photovoltaics
• Solar conversion
• Plane-wave density functional theory
• van-der-Waals interaction

Small clusters of [6,6] phenyl-C61-butyric acid methyl ester (PCBM) molecules are analyzed with respect to their equilibrium geometries and associated electronic as well as energetic properties. Plane wave density functional theory (PWDFT) computations, assisted by molecular dynamics (MD) simulations, are performed on systems of the form PCBMn (n = 1-5). The bonding operative in these units is described as a cooperation between H-O bonding, involving the C5H9O2 groups of the PCBM molecule, and fullerene-fullerene attraction. The maximally stable structures identified tend to include a dimer motif that combines both interaction modes. The great importance of van-der-Waals effects in stabilizing the studied clusters is demonstrated by comparing the PCBM3 series with and without inclusion of a van-der-Waals term in the PWDFT procedure. The two approaches yield reverse orders of stability. A decreasing tendency in the Kohn-Sham HOMO-LUMO gaps of PCBMn with the cluster size may be used to monitor PCBM aggregation in the active layer of organic photovoltaic devices by optical spectroscopy.

• 出版日期2014-5-15