Computational modelling of donor–acceptor conjugated polymers through engineered backbone manipulations based on a thiophene–quinoxaline alternating copolymer
Journal article, 2013

The rapid progress of bulk heterojunction organic photovoltaics has been boosted by (i) design and synthesis of novel conjugated donor materials, (ii) control and optimization of device fabrication, and (iii) the development of new device architectures such as tandem and ternary solar cells. Computationally driven material design has attracted increasing interest to accelerate the search for optimal conjugated photovoltaic materials, and the exploration of chemical methodologies is highly desirable in pushing the efficiency further towards the theoretical limit. Based on the motif of donor–acceptor polymers, over 50 comparable polymers were constructed and investigated, derived from an easily accessible thiophene–quinoxaline alternating polymer donor showing power conversion efficiency up to 7%. We performed a systematic density functional theory (DFT) study on the heteroatom effects of combining fluorine, nitrogen and chalcogen substitutions onto the donor/acceptor units as well as the effect of extending π-conjugation in the donor moiety, in order to gain insights into how structural modifications to the conjugated backbone can affect the molecular structure and electronic properties of a conjugated polymer. It is found that the trends in the energy levels and band gaps of these polymers correlate well to their structural modifications. Finally, by examining the systematically evaluated data in the energy diagram, we proposed three important ways of energy level modulation, showing potential chemical methodologies that can be applicable to further modify and optimize existing polymer backbones. Especially such energy level modulation can be applied to meet the particular requirements of different device architectures (including tandem and ternary solar cells) on the donor components, such as a prominent photocurrent or photovoltage combined with a high efficiency, to further maximize the overall performance of organic photovoltaics. This will provide valuable guidance and chemical methodologies for a judicious material design of conjugated polymers for solar cell applications with desirable photovoltaic characteristics.

Author

Wenliu Zhuang

Chalmers, Chemical and Biological Engineering, Polymer Technology

Angelica Lundin

Chalmers, Chemical and Biological Engineering, Polymer Technology

Mats Andersson

Chalmers, Chemical and Biological Engineering, Polymer Technology

Journal of Materials Chemistry A

2050-7488 (ISSN)

Vol. 2 7 2202-2212

Subject Categories

Materials Engineering

Theoretical Chemistry

Infrastructure

C3SE (Chalmers Centre for Computational Science and Engineering)

Areas of Advance

Materials Science

DOI

10.1039/C3TA14456A

More information

Created

10/6/2017