Magnesium-doped green solar cells using natural chromophores

Abstract

The current study tested the hypothesis of whether specific metal doping may show synergy with plant chromophore-based solar cells using a titanium dioxide (TiO2) electrode. A natural dye-sensitized, magnesium-doped TiO2 solar cell was assembled using the methanol extract from various western African plants including Lawsonia inermis (henna). Mg2+–TiO2 nanoparticles were applied on fluorine-doped tin oxide (FTO) glass to serve as the photoanode of the solar cells with $$I^{ - } /I_{3}^{ - }$$ electrolyte. A surface-modified TiO2 photoanode was prepared through the immersion method using a selective dopant including magnesium and potash. An inductively coupled plasma-optical emission spectrophotometer (ICP-OES) was utilized to characterize the potash dopant for comparative analysis. Instrumental analysis including ultraviolet–visible spectroscopy (UV–Vis), infrared spectroscopy (IR), and gas chromatography and mass spectrometry (GC–MS) analysis were carried out to characterize the natural henna dye extracts. The photovoltaic performance including open-circuit voltage (Voc), short circuit current density (Jsc), current (I), and power output (P) was analyzed quantitatively. ICP-OES analysis demonstrated that potash contains a composite of 26 elemental metals with K and Na accounting for 72.2% (5192.2 mg/kg) and 9.5% (682.6 mg/kg), respectively. GC–MS analysis confirmed the presence of lawsone and tocopherol in henna extracts. Among the tested samples, the Mg-doped TiO2 group generated the highest improvement in Jsc, from 0.66 to 1.28 (mA/cm2), representing a 93% increase. Our experiments demonstrated that the presence of magnesium as a doping agent improves the photogenerated electron transport and the light-harvesting performance of the henna dye to increase the overall efficiency of light-to-electricity conversion of the photovoltaic cells.