Comparative UV–Vis absorption of Bougainvillea spectabilis bract, Moringa oleifera leaf, Mangifera indica leaf and a combined moringa–mango leaf extract for potential dye-sensitized solar cell applications

Natural dye extracts from leaves and bracts are being examined as light absorbers for dye-sensitized solar cells (DSSCs), and where an extract absorbs light is the first property to establish. Ethanolic extracts of Moringa oleifera leaf, Mangifera indica leaf, and Bougainvillea spectabilis bracts were prepared by cold maceration in acidified ethanol, a combined moringa–mango (blend) was prepared, and the absorption of each was recorded with a double-beam spectrophotometer between 200 and 800 nm. The extracts are absorbed in clearly different regions. The mango extract absorbed most at 300–400 nm (absorbance 1.43–1.47), the moringa extract most at 600 nm (0.82), and the Bougainvillea extract most at 500 nm (0.96) among its valid readings. The leaf extracts did not absorb at 700 and 800 nm, whereas the Bougainvillea extract still absorbed there (0.32 and 0.10). The diluted blend absorbed 17–44% more than the expected additive value at 300–500 nm but showed zero absorption at 550 and 600 nm, where both parent extracts do absorb, creating a conflict that cannot be resolved by the current readings. Two Bougainvillea readings (200 and 300 nm) were invalid and were excluded. Because the readings are sparse single values, absorption maxima and optical band gaps are not reported, and the comparison is descriptive. The work is a preliminary optical screening; no solar cell was fabricated or tested.