Green synthesis of copper oxide nanoparticles from pumpkin (Cucurbita maxima) dye extract: a platinum free counter electrode for dye sensitized solar cells

Abstract

Energy is a very critical requirement for all nations that boosts economic growth and development. Dye-sensitized solar cells (DSSCs), the 3rd generation photovoltaic technology which imitate the process of photosynthesis in green plants have of recent gained overwhelming attention in solar harnessing because of their simple structure, affordable cost, simple fabrication technique, little toxicity, and comparatively high efficiency of energy conversion. Currently, Platinum is used as a counter electrode for DSSCs. However, the scarcity and high cost of Pt is still a challenge. In this study, copper oxide (CuO) nanoparticles (NPs) were synthesized using Cucurbita maxima plant leaf dye extract and applied as an electrocatalytic CE in DSSCs. The CuO NPs were characterized using XRD, TEM, UV-Visible spectrophotometer and FTIR to obtain their crystal structure, surface morphology, optical properties and chemical bonds respectively. Three individual natural dyes from pumpkin leaves (P), sweet potato leaves (S) and hibiscus flowers (H), along with their composites, P:H and S:H in varying ratios were extracted, their optical properties studied and used as photosensitizers. The results indicate that the fabricated DSSC with P:H-1:3 composite dyes yielded the highest PCE of 8.7×10-4 %, a short circuit current density (Jsc) of 13.94 μA/cm2 and an open circuit voltage (Voc) of 0.29 V compared to S:H-1:3 composite and individual dyes under one-sun illumination from a solar simulator (AM1.5 100 mWcm-2).