First-principles investigation of organic photovoltaic materials C$_{60}$, C$_{70}$, [C$_{60}$]PCBM, and bis-[C$_{60}$]PCBM using a many-body $G_0W_0$-Lanczos approach

Xiaofeng Qian; Paolo Umari; Nicola Marzari

doi:10.1103/PhysRevB.91.245105

paper

First-principles investigation of organic photovoltaic materials C $_{60}$ , C $_{70}$ , [C $_{60}$ ]PCBM, and bis-[C $_{60}$ ]PCBM using a many-body $G_{0} W_{0}$ -Lanczos approach

arXiv:1411.2149 · doi:10.1103/PhysRevB.91.245105

Abstract

We present a first-principles investigation of the excited-state properties of electron acceptors in organic photovoltaics including C $_{60}$ , C $_{70}$ , [6,6]-phenyl-C $_{61}$ -butyric-acid-methyl-ester ([C $_{60}$ ]PCBM), and bis-[C $_{60}$ ]PCBM using many-body perturbation theory within the Hedin's $G_{0} W_{0}$ approximation and an efficient Lanczos approach. Calculated vertical ionization potentials (VIP) and vertical electron affinities (VEA) of C $_{60}$ and C $_{70}$ agree very well with experimental values measured in gas phase. The density of states of all three molecules is also compared to photoemission and inverse photoemission spectra measured on thin-films, exhibiting a close agreement - a rigid energy-gap renormalization owing to intermolecular interactions in the thin-films. In addition, it is shown that the low-lying unoccupied states of [C $_{60}$ ]PCBM are all derived from the highest-occupied molecular orbitals and the lowest-unoccupied molecular orbitals of fullerene C $_{60}$ . The functional side group in [C $_{60}$ ]PCBM introduces a slight electron transfer to the fullerene cage, resulting in small decreases of both VIP and VEA. This small change of VEA provides a solid justification for the increase of open-circuit voltage when replacing fullerene C $_{60}$ with [C $_{60}$ ]PCBM as the electron acceptor in bulk heterojunction polymer solar cells.

9 pages, 4 figures, and 7 tables

First-principles investigation of organic photovoltaic materials C $_{60}$ , C $_{70}$ , [C $_{60}$ ]PCBM, and bis-[C $_{60}$ ]PCBM using a many-body $G_{0} W_{0}$ -Lanczos approach

Abstract

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First-principles investigation of organic photovoltaic materials C60​, C70​, [C60​]PCBM, and bis-[C60​]PCBM using a many-body G0​W0​-Lanczos approach

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Cited by in corpus (5)

First-principles investigation of organic photovoltaic materials C $_{60}$ , C $_{70}$ , [C $_{60}$ ]PCBM, and bis-[C $_{60}$ ]PCBM using a many-body $G_{0} W_{0}$ -Lanczos approach