Explore fused-ring core incorporated A-π-D-π-A type acceptors and their application in organic solar cells: Insight into molecular conformation, optical and electrochemical properties, film morphology, and energy loss. (December 2021)

• Record Type: Journal Article
• Authors: Zhang, Zhuohan; Zhu, Jintao; Lv, Yifan; Lan, Ai; Lu, Hong; Chen, Fei; Huang, Wei
• Is Part Of: Dyes and pigments. Volume 196(2022)
• Publication Date: 2021-12
• Subjects: Organic solar cells -- π-bridge -- Core change -- Nonfullerene acceptors -- Low energy loss; Dyes and dyeing -- Periodicals; Pigments -- Periodicals; 667.2
• DOI: 10.1016/j.dyepig.2021.109572
• Languages: English
• ISSNs: 0143-7208

Abstract

Abstract: Acceptor-π-Donor-π-Acceptor (A-π-D-π-A) type fused-ring electron acceptors (FREAs) are a class of important nonfullerene acceptors for fabricating high efficiency organic solar cells (OSCs). However, limited by the rare types of the central D core, the efficiencies of the OSCs based on A-π-D-π-A FREAs are falling behind. In this work, dithienopyrrolobenzothiadiazole (DTPBT) was employed in developing A-π-D-π-A type FREAs, and was assessed as a D core. DTPBT based FREAs were synthesized and compared with the typical A-π-D-π-A type FREAs using IDT as the D core, from aspects of molecular conformation, optical and electrochemical properties, blend film morphology, and energy loss. Compared to traditional IDT based A-π-D-π-A type FREAs (IRIC-4F), A-π-D-π-A FREAs containing DTPBT (BTOT-OD-4F) showed C-type molecular conformation, redshifted absorption and downshifted energy levels. As a result, the corresponding devices achieved an efficiency of over 13% with improved JSC of 23.44 mA cm −2 and a fair FF of 66.9%. Meanwhile, the energy loss of the PBDB-T: BTOT-OD-4F blends reduced effectively, due to the contribution of suppressed nonradiative recombination. Above all, DTPBT has presented its potential in developing highly efficient A-π-D-π-A type FREAs. To realize the best performance of the novel acceptors, further systematic and synergetic optimization of the molecule structure and device fabrication are needed. This work has demonstrated a new design manner of A-π-D-π-A type FREAs through exploring novel fused-ring cores, which facilitates reduced energy loss of the corresponding devices. Graphical abstract: The impacts of Fused-ring core difference on molecular conformation, optical and electrochemical properties, film morphology, and energy loss were systematically explored. The DAD typed core incorporated acceptor shows an extended absorption range and lower energy levels compared with D typed core based counterpart, and the related devices exhibited a higher J SC, μ e and lower energy loss. Image 1 Highlights: Two π-bridged nonfullerene acceptors (π-NFAs) IRIC-4F and BTOT-OD-4F were developed with strong near-infrared absorption. BTOT-OD-4F is an exploratory example of π-NFAs with an electron-deficient core. The efficiency of BTOT-OD-4F photovoltaic devices was achieved over 13%, which was one of the highest values for π-NFAs based photovoltaic devices. Smaller energy loss was observed in the novel π-NFAs fabricated devices.