Fluorine-substituted indolo-thiadiazoloquinoxaline-based D-A type polymers for photovoltaic applications

Abstract

Two D-A type conjugated polymers, in which the electron-donating benzodithiophene monomers are connected to the electron-accepting indolo-thiadiazoloquinoxaline (ITQ) monomers via a thiophene bridge, are synthesized under Stille coupling conditions. Once the reference PB-ITQ is prepared, one fluorine atom is incorporated into the ITQ unit of PB-ITQ to afford the additional target polymer PB-ITQF. An inverted-type device with the configuration of indium tin oxide (ITO)/ZnO/Polymer:PC₇₁BM/MoO₃/Ag is utilized to examine the photovoltaic properties of the two polymers. Owing to the positive contributions of fluorine atoms, all the photovoltaic parameters of the device based on PB-ITQF such as the short-circuit current density, open-circuit voltage, and fill factor are improved as compared with those of the device based on PB-ITQ. As a result, the highest PCE of 2.32% is achieved from the fullerene-based polymer solar cell based on PB-ITQF.

Keywords:

• Benzodithiophene
• fluorine atom
• indolo-thiadiazoloquinoxaline
• polymer solar cells

Additional information

Funding

This work was supported by the Pukyong National University Research Fund in 2019.