Low-cost anthocyanin dye from broad bean flower (Parkia platycephala) for Pt-free DSSC

Abstract

The growing interest in clean and renewable energy sources is driving research into technologies such as dye-sensitized solar cells (DSSCs). Despite their potential, DSSCs still face limitations related to efficiency and cost. This work investigated the potential of anthocyanin extract from broad bean flower (Parkia platycephala) as a sensitizer in DSSCs. Anthocyanins were extracted from different parts of the flower, with the granule extract (EAG) being the richest in anthocyanins (369.5 mg/100 g). The EAG was characterized by several techniques, including atomic absorption spectrometry, which revealed the presence of metals such as rubidium, calcium and potassium. A new material, zinc-anthocyanin extract (Zn-EAG), was synthesized from the reaction of EAG with a zinc salt. Spectroscopic and colorimetric analysis of Zn-EAG confirmed the chelation of anthocyanins to Zn(II). DSSCs were fabricated using EAG and Zn-EAG as sensitizers, and their photovoltaic performance was evaluated under natural solar irradiation. The results showed that DSSC with Zn-EAG presented better performance, even under diffuse light, while DSSC with EAG presented voltage drop under shade conditions. The chelation of anthocyanins to Zn(II) in Zn-EAG favors electron transfer, resulting in better DSSC performance. This study demonstrates the potential of P. platycephala as a source of materials for application in DSSCs, contributing to the development of clean and sustainable energy technologies.