Subtle Side Chain Triggers Unexpected Two-Channel Charge Transport Property Enabling 80% Fill Factors and Efficient Thick-Film Organic Photovoltaics

Yonghai Li; Lu Yu; Liangliang Chen; Chenyu Han; Huanxiang Jiang; Zitong Liu; Nan Zheng; Jiuxing Wang; Mingliang Sun; Renqiang Yang; Xichang Bao

doi:10.1016/j.xinn.2021.100090

Subtle Side Chain Triggers Unexpected Two-Channel Charge Transport Property Enabling 80% Fill Factors and Efficient Thick-Film Organic Photovoltaics

Innovation (Camb). 2021 Feb 5;2(1):100090. doi: 10.1016/j.xinn.2021.100090. eCollection 2021 Feb 28.

Authors

Yonghai Li^{1

2}, Lu Yu^{1

3}, Liangliang Chen⁴, Chenyu Han¹, Huanxiang Jiang¹, Zitong Liu⁴, Nan Zheng⁵, Jiuxing Wang⁶, Mingliang Sun³, Renqiang Yang^{1

7}, Xichang Bao^{1

2}

Affiliations

¹ CAS Key Laboratory of Bio-based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China.
² Functional Laboratory of Solar Energy, Shandong Energy Institute, Qingdao 266101, China.
³ School of Material Science and Engineering, Ocean University of China, Qingdao 266100, China.
⁴ Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
⁵ State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640, China.
⁶ School of Materials Science and Engineering, Qingdao University, Qingdao 266071, China.
⁷ Key Laboratory of Optoelectronic Chemical Materials and Devices (Ministry of Education), School of Chemical and Environmental Engineering, Jianghan University, Wuhan 430056, China.

Abstract

To clearly show how important the impact of side chains on organic solar cells (OSCs) is, we designed three acceptors IDIC-CxPh (x = 4, 5, or 6) via subtle side-chain regulation. Despite this small change, significant distinctions were detected. IDIC-C4Ph devices achieve an optimal efficiency of 13.94% under thermal annealing, but thermal-assistant solvent-vapor annealing hugely suppresses the efficiencies to 10%. However, the C6Ph side chain endows extremely disordered stacking orientations, generating moderate efficiencies of ~12.50%. Excitingly, the IDIC-C5Ph affords an unexpected two-channel π-π charge transport (TCCT) property, boosting the fill factor (FF) by up to 80.02% and efficiency to 14.56%, ranking the best among five-ring fused-ladder-type acceptors. Impressively, the special TCCT behavior of IDIC-C5Ph enables 470 nm thick-film OSC with a high FF of up to 70.12% and efficiency of 13.01%, demonstrating the great promise in fabricating large-scale OSCs.

Keywords: molecular assembly; organic solar cells; side chain; thick-film; two-channel charge transport.