Side Chain Engineered Naphthalene Diimide-Based Terpolymer for Efficient and Mechanically Robust All-Polymer Solar Cells

• DOI: 10.1021/acs.chemmater.0c04721
• Publication Date: 2021-01-19T19:44:17Z
• Authors: Jin-Woo Lee; Nayoun Choi; Dongjun Kim; Tan Ngoc-Lan Phan; Hyunbum Kang; Taek-Soo Kim; Bumjoon J. Kim
• Keywords: Side chain; Electron Mobility

The recent evolution of new polymer acceptors (PAs) using small-molecule building blocks with high light absorption has significantly increased the power conversion efficiency (PCE) all-polymer solar cells (all-PSCs), but their mechanical properties are typically poor. Thus, poly[[N,N′-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5′-(2,2′-bithiophene)] (N2200) is still considered one most successful PAs in all-PSCs. Herein, we report development naphthalene dimide-based (NDI-PAs) that enable achievement both superior PCEs and robustness all-PSCs compared to those N2200-based devices. Our approach very simple effective for constructing a series [PNDIHD/DT-x, where x = 0–1], consisting two NDI units different side chains (2-hexyldecyl (HD) 2-decyltetradecyl (DT)). PNDIHD/DT-0.41-based poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b′]dithiophene))-alt-(5,5-(1′,3′-di-2-thienyl-5′,7′-bis(2-ethylhexyl)benzo[1′,2′-c:4′,5′-c′]dithiophene-4,8-dione))] (PBDB-T) donor achieve PCE 9.3%, which outperforms device (PCE 7.7%). This mainly attributed enhanced charge generation transport abilities all-PSCs, as result optimal domain size purity well electron mobility. Importantly, PBDB-T:PNDIHD/DT-0.41 blend shows excellent robustness, crack onset strain (COS) 30% toughness 7.5 MJ m–3. In addition, flexible cell (FPSC) initial 6.73%, maintained over 6% even after bending 1500 times.