?-Expanded dibenzo-BODIPY with near-infrared light absorption: Investigation of photosensitizing properties of NiO-based p-type dye-sensitized solar cells

Much attention has been devoted to the synthesis of dyes that absorb near-infrared (NIR) radiation because of numerous demands for them as functional materials. Given that NIR sensitizers applicable to p-type dye-sensitized solar cell (DSSC) devices are extremely rare, ?-extended dibenzo-BODIPY sensitizer 1 containing triphenylamine and nitrothiophene units was synthesized; the absorption spectrum of 1 showed an intense absorption band at 730 nm with a molar extinction coefficient of 7.14 × 104 M-1 cm-1. A p-type DSSC device with a 1-loaded NiO electrode was fabricated and its cell performance was investigated. It showed an open circuit voltage (VOC), a short circuit current density (JSC), and a fill factor (FF) of 79 mV, 0.61 mA cm-2, and 0.25, respectively. Consequently, the power conversion efficiency was 0.012%. Its performance was low, mainly owing to very fast recombination between the NiO and reduced dye at the surface of the electrode. However, EQE measurement showed that the 1-loaded p-type DSSC devices convert photons into current at wavelengths up to 850 nm, so further investigation to improve the cell performance is deserved. © 2019 Elsevier LtdTakahashi Industrial and Economic Research FoundationThis research is partially supported by Takahashi Industrial and Economic Research Foundation . Appendix A -