Bandgap-altered photo-sensing and toxic dye degradation in Al-modified CuO

Abstract

The Cu1-xAlxO (x= 0 , 0.0156 , 0.0234 , 0.0312 , 0.0468) has been synthesized using the sol–gel method. An XRD and Raman spectrum of samples confirm the phase purity and present phonon modes in samples. The direct bandgap tuned from 3.75 to 3.55 eV. However, an insignificant variation of the indirect bandgap from 1.4 to 1.41 eV was observed. The Hall effect experiment suggests the mobility, carrier concentration, and conductivity variation of all samples. The modifications in conductivity, mobility, and carrier concentration were also explained. The modified Urbach energy and conductivity are also detailed in terms of sensitivity and photoresponsivity. Effect of different wavelengths (290 nm, 450 nm, 540 nm, 640 nm) of light on surface conductivity of sol–gel-synthesized Cu1-xAlxO material has been observed. The photoresponsivity (Δ I) and % sensitivity of all samples were studied. The correlation of lattice strain and Urbach energy with the sensitivity is explained. The drastic reduction in % sensitivity from UV (24%) to RGB (below 1%) promises the solar-blind or insensitive nature of Al-doped CuO. © 2022, The Author(s), under exclusive licence to EDP Sciences, Springer-Verlag GmbH Germany, part of Springer Nature.