The Influence of Alkoxy Substitutions on the Properties of Diketopyrrolopyrrole-Phenyl Copolymers for Solar Cells
Journal article, 2013

A previously reported diketopyrrolopyrrole (DPP)-phenyl copolymer is modified by adding methoxy or octyloxy side chains on the phenyl spacer. The influence of these alkoxy substitutions on the physical, opto-electronic properties, and photovoltaic performance were investigated. It was found that the altered physical properties correlated with an increase in chain flexibility. Well-defined oligomers were synthesized to verify the observed structure-property relationship. Surprisingly, methoxy substitution on the benzene spacer resulted in higher melting and crystallization temperatures in the synthesized oligomers. This trend is not observed in the polymers, where the improved interactions are most likely counteracted by the larger conformational possibilities in the polymer chain upon alkoxy substitution. The best photovoltaic performance was obtained for the parent polymer: fullerene blends whereas the modifications on the other two polymers result in reduced open-circuit voltage and varying current densities under similar processing conditions. The current densities could be related to different polymer: fullerene blend morphologies. These results show that supposed small structural alterations such as methoxy substitution already significantly altered the physical properties of the parent polymer and also that oligomers and polymers respond divergent to structural alterations made on a parent structure.

Density Functional Theory (DFT)

DPP

synthesis

conjugated polymers

organic solar cells

Author

Zandra George

Chalmers, Chemical and Biological Engineering, Polymer Technology

Renee Kroon

Chalmers, Chemical and Biological Engineering, Polymer Technology

R. Gehlhaar

PV/PMEPV/OPV

Gabin Gbabode

Université libre de Bruxelles (ULB)

Angelica Lundin

Chalmers, Chemical and Biological Engineering, Polymer Technology

Stefan Hellström

Chalmers, Chemical and Biological Engineering, Polymer Technology

Christian Müller

Chalmers, Chemical and Biological Engineering, Polymer Technology

Yves Geerts

Université libre de Bruxelles (ULB)

P. Heremans

PV/PMEPV/OPV

Mats Andersson

Chalmers, Chemical and Biological Engineering, Polymer Technology

Materials

1996-1944 (ISSN)

Vol. 6 7 3022-3034

Subject Categories

Materials Engineering

DOI

10.3390/ma6073022

More information

Latest update

5/3/2018 9