Synergistic Effects of Side‐Chain Engineering and Fluorination on Small Molecule Acceptors to Simultaneously Broaden Spectral Response and Minimize Voltage Loss for 13.8% Efficiency Organic Solar Cells. Issue 11 (19th July 2019)

• Record Type: Journal Article
• Authors: Fan, Qunping; Su, Wenyan; Zhang, Ming; Wu, Jingnan; Jiang, Yufeng; Guo, Xia; Liu, Feng; Russell, Thomas P.; Zhang, Maojie; Li, Yongfang
• Is Part Of: Solar RRL. Volume 3:Issue 11(2019)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-07-19
• Subjects: fluorination -- organic solar cells -- power conversion efficiency -- side-chain engineering -- small molecule acceptors; Solar energy -- Periodicals; Photovoltaic power generation -- Periodicals; Solar energy -- Research -- Periodicals; Photovoltaic power generation -- Research -- Periodicals; Periodicals; 333.7923
• DOI: 10.1002/solr.201900169
• Languages: English
• ISSNs: 2367-198X

Abstract

Abstract : Herein, three small molecule (SM)‐acceptors (POIT‐IC, POIT‐IC2F, and POIT‐IC4F) are developed by combining the side‐chain engineering located on the sp 3 ‐hybridized carbon atoms of the fused‐ring core and the fluorination of end groups. From ITIC to POIT‐IC, POIT‐IC2F, and then to POIT‐IC4F, the SM‐acceptors show gradually broadened absorption spectra, increased maximum extinction coefficient, crystallinity, and electron mobilities due to the synergistic effects of side‐chain engineering and fluorination. Compared with nonfluorinated ITIC and POIT‐IC, as fluorination broadens the molecular spectra, POIT‐IC2F and POIT‐IC4F with alkoxyphenyl side chains show less decreased LUMO levels than IT‐IC2F and IT‐IC4F with alkylphenyl side chains, which are conducive to both higher V oc and J sc for organic solar cells (OSCs). Combined with polymer donor PM6, the POIT‐IC4F‐based OSCs achieve a device efficiency of up to 13.8% with a high V oc of 0.91 V and J sc of 20.9 mA cm −2, which are significantly higher than that of the control OSCs based on ITIC (8.9%), POIT‐IC (10.1%), or IT‐IC4F (12.2%). An efficiency of 13.8% is one of the highest PCEs reported for the annealing‐free OSCs. Our results show that the synergistic effects of side‐chain engineering and fluorination on SM‐acceptor can simultaneously broaden spectral response and minimize voltage loss of OSCs and ultimately achieve high device efficiency. Abstract : A new small molecule (SM)‐acceptor, POIT‐IC4F, is developed. Due to the synergistic effects of side‐chain engineering and fluorination on the SM‐acceptor to simultaneously broaden spectral response and minimize voltage loss, the annealing‐free organic solar cells achieve a high device efficiency of 13.8%.