Enhancement of intra- and inter-molecular π-conjugated effects for a non-fullerene acceptor to achieve high-efficiency organic solar cells with an extended photoresponse range and optimized morphology

Ning Wang, Lingling Zhan, Shuixing Li, Minmin Shi, Tsz Ki Lau, Xinhui Lu, Rafi Shikler, Chang Zhi Li, Hongzheng Chen

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

In this work, a new A-D-A type non-fullerene electron acceptor, DF-PCNC, which possesses an electron-donating (D) core constructed by linking a 2,5-difluorobenzene ring with two cyclopentadithiophene moieties and two electron-accepting (A) end-groups of 2-(3-oxo-2,3-dihydro-1H-cyclopenta[b]naphthalen-1-ylidene)malononitrile (NC), is designed and synthesized. Because of the extension of the π-conjugation system, DF-PCNC shows stronger and more red-shifted absorption peaks while compared to those of its counterpart, DF-PCIC, which has the same D core but smaller A terminals of 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (IC). Furthermore, NC groups can enhance the intermolecular π-π stacking of DF-PCNC in the condensed state. Thus, when it is blended with a polymer donor, PBDB-T, to fabricate organic solar cells (OSCs), good morphologies of the blended films are achieved through appropriate optimizations: both donor and acceptor form highly crystalline phase-separation domains with appropriate nanoscaled sizes, which is beneficial to charge generation and transport in OSCs. As a result, the short-circuit current density (JSC) of the PBDB-T:DF-PCNC device is increased by 16% compared with that of the PBDB-T:DF-PCIC one, and a high fill factor (FF) of 72.62% is maintained, leading to a better power conversion efficiency (PCE) of 11.63%, which is the highest value for OSCs based on non-fullerene acceptors adopting decreased fused-ring D cores to date.

Original languageEnglish
Pages (from-to)2006-2012
Number of pages7
JournalMaterials Chemistry Frontiers
Volume2
Issue number11
DOIs
StatePublished - 1 Nov 2018

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