Issue 10, 2016

A non-fullerene electron acceptor modified by thiophene-2-carbonitrile for solution-processed organic solar cells

Abstract

Effective electron acceptor materials usually have a deep lowest unoccupied molecular orbital (LUMO) energy level that can split excitons and generate current. A non-fullerene electron acceptor (F8-DPPTCN) was developed, using fluorene as the core with arms of diketopyrrolopyrrole (DPP) having thiophene-2-carbonitrile as the terminal units. The new molecule had a LUMO of −3.65 eV and a narrow bandgap (Eg) of 1.66 eV, owing to the electronegativity of the thiophene-2-carbonitrile group and its conjugation with DPP units. Organic solar cells (OSCs) with F8-DPPTCN as the acceptor and poly(3-hexylthiophene) (P3HT) as the donor were fabricated. A power conversion efficiency (PCE) of 2.37% was obtained with an open-circuit voltage (Voc) of 0.97 V, a short-circuit current (Jsc) of 6.25 mA cm−2, and a fill factor (FF) of 0.39. Structural characterization showed that P3HT and F8-DPPTCN were kinetically trapped in a weakly separated state whereas thermal annealing led to the crystallization of P3HT and the formation of a network structure with a mesh-size of several hundred nanometers. When a solvent additive, diiodooctane, was used and the mixture was thermally annealed, both P3HT and F8-DPPTCN crystallized and a multi-length scale network was formed. Though the PCEs were low, the changes in the PCE could be correlated with the morphological changes, opening pathways to increase performance further.

Graphical abstract: A non-fullerene electron acceptor modified by thiophene-2-carbonitrile for solution-processed organic solar cells

Supplementary files

Article information

Article type
Paper
Submitted
24 ربيع الأول 1437
Accepted
24 ربيع الثاني 1437
First published
25 ربيع الثاني 1437

J. Mater. Chem. A, 2016,4, 3777-3783

A non-fullerene electron acceptor modified by thiophene-2-carbonitrile for solution-processed organic solar cells

S. Li, J. Yan, C. Li, F. Liu, M. Shi, H. Chen and T. P. Russell, J. Mater. Chem. A, 2016, 4, 3777 DOI: 10.1039/C6TA00056H

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