Dye-sensitized solar cells conventionally used environmentally concerning metal-based dyes. Natural dyes are emerging as safe easy-to-use alternatives. Six natural-dye extracts from Algerian plants, Lawsonia inermis leaves (ND1), Pistacia atlantica basidiomycete (Inonotus hispidus) (ND2), D'bagha tannin powder (ND3), Hammada scoparia flowers (ND4), Phillyrea angustifolia fruit (ND5), and Opuntia stricta fruit (ND6), are examined, where ND2, ND3, ND4, and ND5 are newly studied. Electronic-absorption spectra indicate optical-band gaps ranging 1.79-2.78 eV. From cyclovoltammetry, the extracts possess LUMO levels ranging (-3.66)-(-4.04 eV), and HOMO levels ranging (-5.45)-(-6.72 eV). ND1, ND2, ND4, ND5 and ND6 LUMO levels are higher than TiO₂ conduction band (-4.2 eV) by 0.26-0.54 eV, enough for injection. ND3 LUMO level (-4.04 eV) is only 0.16 eV above TiO₂, not enough for efficient injection. All dyes have HOMO levels below I⁻/I₃⁻ redox potential, for dye regeneration. From atomic-force microscopy, anatase TiO₂ nanoparticles (18.46-3.39 nm, porosity 76%) confirm the stated manufacturer specifications. High root-mean-square values in ND6 (7.74) and ND2 (8.11) indicate higher adsorption. Fourier-transform infrared-spectra confirm dye-TiO₂ interaction via carbonyl and hydroxyl groups. TiO₂-based natural dye-sensitized solar cells (NDSSCs) are fabricated using activated-charcoal counter electrodes. Under AM1.5G, ND2 exhibits highest performance, with efficiency 0.073%, short-circuit current density 0.502 mA/cm² and open-circuit voltage 0.401 V, due to high chemical capacitance 8.99 µF despite moderate recombination resistance 400.6 W. ND6 demonstrates highest fill factor 49.15%. From electrochemical-impedance spectroscopy, the counter electrode demonstrates significant resistance (R_CE>61 W), which lowers efficiency. Recommendations to improve the NDSSCs are discussed here.

Title

Chemical Papers

Publisher

Springer-Verlach

Publisher Country

Slovakia

Indexing

Thomson Reuters

Impact Factor

2.5

Publication Type

Both (Printed and Online)

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Year

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Pages

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