Photovoltaic performance and photostability of anthocyanins, isoquinoline alkaloids and betalains as natural sensitizers for DSSCs

Abstract

Natural dyes extracted from fruit (FBV) and root (RBV) of barberry (Berberis vulgaris) and fruit (FPA) and stalk (SPA) of pokeweed (Phytolacca americana) were used as sensitizers for dye-sensitized solar cells (DSSCs). All the extracts were employed without any modifications, such as purifications or addition of stabilizers. Anthocyanin and isoquinoline alkaloid were identified as the main components for FBV and RBV extracts, respectively, whereas betalain for FPA and SPA extracts. SPA and FPA displayed much broader absorption spectra than the others, which is beneficial to light harvesting capability. When tested in DSSCs, the highest power conversion efficiency (PCE) of 3.04% is obtained by SPA, and this followed by PCEs of 2.97, 2.35 and 2.01% for FPA, RBV and FBV, respectively. The lowest PCE for FBV can be attributed to poor electron transfer ability, which may cause reduced photocurrent and photovoltage. On the other hand, after 120 h of sunlight irradiation, FBV, RBV, FPA and SPA retained the PCE values as 91, 54, 63 and 69% of the initial efficiencies. The moderate photovoltaic performance with good photostability for the anthocyanin extract may favorable for low-cost and environmental-friendly DSSC applications.