Modulating Structure Ordering via Side-Chain Engineering of Thieno[3,4- b]thiophene-Based Electron Acceptors for Efficient Organic Solar Cells with Reduced Energy Losses

Feng Liu; Jianyun Zhang; Yuming Wang; Shanshan Chen; Zichun Zhou; Changduk Yang; Feng Gao; Xiaozhang Zhu

doi:10.1021/acsami.9b10641

Modulating Structure Ordering via Side-Chain Engineering of Thieno[3,4- b]thiophene-Based Electron Acceptors for Efficient Organic Solar Cells with Reduced Energy Losses

ACS Appl Mater Interfaces. 2019 Sep 25;11(38):35193-35200. doi: 10.1021/acsami.9b10641. Epub 2019 Sep 10.

Authors

Feng Liu^{1

2}, Jianyun Zhang^{1

2}, Yuming Wang³, Shanshan Chen⁴, Zichun Zhou^{1

2}, Changduk Yang⁴, Feng Gao³, Xiaozhang Zhu^{1

2}

Affiliations

¹ Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry , Chinese Academy of Sciences , Beijing 100190 , China.
² School of Chemistry and Chemical Engineering , University of Chinese Academy of Sciences , Beijing 100049 , China.
³ Department of Physics Chemistry and Biology (IFM) , Linköping University , Linköping SE-581 83 , Sweden.
⁴ Department of Energy Engineering, School of Energy and Chemical Engineering, Low Dimensional Carbon Material Center , Ulsan National Institute of Science and Technology , Ulsan 689-798 , South-Korea.

PMID: 31405275
DOI: 10.1021/acsami.9b10641

Abstract

Nonfullerene-based organic solar cells (OSCs) have made a huge breakthrough in the recent years. Introducing a proper side chain on the π-conjugated backbone plays a vital role for further improving the power conversion efficiency (PCE) of OSCs due to easy tuning of the physical properties of the molecule such as absorption, energetic level, solid-state stacking, and charge transportation. More importantly, the side chain significantly affected the blend film's morphology and thus determined the PCEs of the devices. In this work, two low-band-gap nonfullerene acceptors, ATT-4 and ATT-5, with an alkyl or branched alkyl substitute on indacenodithiophene (IDT) and thieno[3,4-b]thiophene (TbT) backbone were synthesized for investigating the effect of the substituent on the performance of the nonfullerene acceptors (NFAs). In comparison to ATT-1 with p-hexylphenyl-substituted IDT and n-octyl-substituted TbT moieties, ATT-4 and ATT-5 exhibit better crystallinity with shorter interchain distance and ordered molecular structure in neat and the corresponding blend films. The tailored ATT-5 exhibits a high PCE of 12.36% with a V_oc of 0.93 V, J_sc of 18.86 mA cm^-2, and fill factor (FF) of 0.71, blending with a wide-band-gap polymer donor PBDB-T. Remarkably, although ATT-4 and ATT-5 exhibit broader light absorption, the devices obtained higher V_oc than that of ATT-1 mainly due to the reduced nonradiative recombination in the blend films. These results implied that side-chain engineering is an efficient approach to regulate the electronic structure and molecular packing of NFAs, which can well match with polymer donor, and obtain high PCEs of the OSCs with improved V_oc, J_sc, and FF, simultaneously.

Keywords: energy loss; nonfullerene acceptors; organic solar cells; side-chain engineering; thieno[3,4-b]thiophene.