Glycol bearing perylene monoimide based non-fullerene acceptors with increased dielectric permittivity

• Published in: Monatshefte für Chemie Vol. 154; no. 12; pp. 1369 - 1381
• Main Authors: Fürk, Peter, Hofinger, Jakob, Reinfelds, Matiss, Rath, Thomas, Amenitsch, Heinz, Scharber, Markus Clark, Trimmel, Gregor
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01.12.2023; Springer Nature; Springer Nature B.V
• Subjects: Analytical Chemistry; Carbazoles; Chemistry; Chemistry and Materials Science; Chemistry, Multidisciplinary; Chemistry/Food Science; Dielectric properties; Energy conversion efficiency; Ethylene glycol; Excitons; Fullerenes; Inorganic Chemistry; Organic Chemistry; Original Paper; Permittivity; Photovoltaic cells; Physical Chemistry; Physical Sciences; Science & Technology; Solar cells; Synthesis; Theoretical and Computational Chemistry; Thermal stability; Organic semiconductors; Density functional theory; Material science; Organic photovoltaics; Optical properties; STRATEGY; CONSTANT; FLUORENE
• ISSN: 0026-9247; 1434-4475
• DOI: 10.1007/s00706-022-02956-2

Perylene monoimide based electron acceptors have great properties for use in organic solar cells, like thermal stability, strong absorption, and simple synthesis. However, they typically exhibit low values for the dielectric permittivity. This hinders efficient exciton dissociation, limiting the achievable power conversion efficiencies. In this work, we present the synthesis and utilization of two new acceptor–donor-acceptor (A-D-A) molecules, comprising perylene monoimide as electron withdrawing A unit. Oligo ethylene glycol side chain modified carbazole (PMI-[ C-OEG ]) and fluorene (PMI-[ F-OEG ]) linkers were used as electron rich D units, respectively. The polar side chains are expected to increase the polarizability of the molecules and, thus, their permittivity according to the Clausius–Mossotti relationship. We found that the incorporation of glycol chains improved the dielectric properties of both materials in comparison to the reference compounds with alkyl chains. The permittivity increased by 18% from 3.17 to 3.75 for the carbazole-based non-fullerene acceptor PMI-[ C-OEG ] and by 12% from 3.10 to 3.47 for the fluorene-based acceptor PMI-[ F-OEG ]. The fabricated solar cells revealed power conversion efficiencies of 3.71 ± 0.20% (record 3.92%) with PMI-[ C-OEG ], and 1.21 ± 0.06% (record 1.51%) with PMI-[ F-OEG ]. Graphical abstract