Modulating molecular aggregation by facile heteroatom substitution of diketopyrrolopyrrole based small molecules for efficient organic solar cells
Journal article, 2015

In conjugated polymers and small molecules of organic solar cells, aggregation induced by intermolecular interactions governs the performance of photovoltaics. However, little attention has been paid to the connection between molecular structure and aggregation within solar cells based on soluble small molecules. Here we demonstrate modulation of intermolecular aggregation of two synthesized molecules through heteroatom substitution to develop an understanding of the role of aggregation in conjugated molecules. Molecule 1 (M1) based on 2-ethylhexyloxy-benzene substituted benzo[1,2-b:4,5-b']dithiophene (BDTP) and diketopyrrolopyrrole (DPP) displays strong aggregation in commonly used organic solvents, which is reduced in molecule 2 (M2) by facile oxygen atom substitution on the BDTP unit confirmed by absorption spectroscopy and optical microscopy, while it successfully maintains molecular planarity and favorable charge transport characteristics. Solar cells based on M2 exhibit more than double the photocurrent of devices based on M1 and yield a power conversion efficiency of 5.5%. A systematic investigation of molecular conformation, optoelectronic properties, molecular packing and crystallinity as well as film morphology reveals structure dependent aggregation responsible for the performance difference between the two conjugated molecules.

Materials Science



Energy & Fuels



conjugated polymers

high fill factors


conversion efficiency

field-effect transistors

charge-transfer excitons



D. P. Qian

Linköping University

B. Liu

Linköping University

S. H. Wang

Linköping University

Scott Himmelberger

Stanford University

M. Linares

Linköping University

M. Vagin

Linköping University

Christian Müller

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Polymer Technology

Z. F. Ma

Linköping University

S. Fabiano

Linköping University

M. Berggren

Linköping University

Alberto Salleo

Stanford University

Olle Inganäs

Linköping University

Y. P. Zou

Central South University

Fengling Zhang

Linköping University

Journal of Materials Chemistry A

20507488 (ISSN) 20507496 (eISSN)

Vol. 3 48 24349-24357

Driving Forces

Sustainable development

Subject Categories

Chemical Engineering



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3/6/2018 1