### Abstract

A detailed quantum chemical simulation of
the excitonic and charge-transfer (CT) states of a bulk
heterojunction model containing poly(thieno[3,4-b]-
thiophene benzodithiophene) (PTB1)/[6,6]-phenyl-C61-
butyric acid methyl ester (PCBM) is reported. The largest
molecular model contains two stacked PTB1 trimer chains
interacting with C60 positioned on top of and lateral to the
(PTB1)3 stack. The calculations were performed using the
algebraic diagrammatic construction method to second
order (ADC(2)). One main result of the calculations is
that the CT states are located below the bright inter-chain
excitonic state, directly accessible via internal conversion
processes. The other important aspects of the calculations
are the formation of discrete bands of CT states
originating from the lateral C60’s and the importance of
inter-chain charge delocalization for the stability of the CT
states. A simple model for the charge separation step is
also given, revealing the energetic feasibility of

Original language | English |
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Pages (from-to) | 18252-18255 |

Journal | Journal of the American Chemical Society |

State | Published - 2013 |

## Fingerprint Dive into the research topics of 'Ab Initio Modeling of Excitonic and Charge-Transfer States in Organic Semiconductors: The PTB1/PCBM Low Band Gap System'. Together they form a unique fingerprint.

## Cite this

Itamar Borges, J., Aquino, A., Köhn, A., Nieman, R., Hase, W., Chen, L. X., & Lischka, H. (2013). Ab Initio Modeling of Excitonic and Charge-Transfer States in Organic Semiconductors: The PTB1/PCBM Low Band Gap System.

*Journal of the American Chemical Society*, 18252-18255.