Naphthobisthiadiazole-Based π-Conjugated Polymers for Nonfullerene Solar Cells: Suppressing Intermolecular Interaction Improves Photovoltaic Performance
Journal
ACS Applied Materials and Interfaces
Journal Volume
14
Journal Issue
12
Pages
14400-14409
Date Issued
2022
Author(s)
Abstract
Naphthobisthiadiazole has been known as a promising building unit of π-conjugated polymers for organic photovoltaics (OPVs). Here, we synthesized new NTz-based polymers that were combined with a benzodithiophene (BDT) unit having alkylthienyl substituents in the polymer backbone, named PNTzBDT, and PNTzBDT-F and PNTzBDT-Cl with fluorine and chlorine groups in the substituents, respectively. The polymers had significantly improved solubility than the previously reported NTz-based polymer (PNTz4T), most likely due to the torsion of the alkylthienyl substituents with respect to the BDT moiety, which suppresses the intermolecular interaction between the backbones. Despite the lower intermolecular interaction and thereby lower crystallinity, these polymers, in particular PNTzBDT and PNTzBDT-F, exhibited higher photovoltaic performances, with power conversion efficiencies as high as 13.3%, than PNTz4T in the cells that used Y6 as the acceptor material. The improved performance was ascribed to the enhanced miscibility of the polymers with the nonfullerene acceptor due to the increased solubility, which in addition led to the better charge generation and reduced charge recombination. These results indicate that NTz-based π-conjugated polymers have high potential for nonfullerene-based OPVs. © 2022 American Chemical Society. All rights reserved.
Subjects
benzodithiophene; naphthobisthiadiazole; nonfullerene; organic photovoltaics; semiconducting polymer; π-conjugated polymer
Other Subjects
Conjugated polymers; Crystallinity; Polymer solar cells; Semiconducting polymers; Solar power generation; Benzodithiophene; Building units; Intermolecular interactions; Naphthobisthiadiazole; Nonfullerene; Organic photovoltaics; Photovoltaic performance; Polymer backbones; Synthesised; π-conjugated polymer; Solubility
Type
journal article