Optoelectronic properties of fluorine and antimony-doped tin dioxide nanoparticles

Nano-sized tin dioxide SnO2 (TO) has garnered great potential for use in optoelectronic applications, gas sensors, and solar cell technology thanks to its unique properties. These properties can be further enhanced by altering dopants and crystallinity. To achieve these aims, we successfully synthesized nanoparticles of fluorine (F) and antimony (Sb) doped tin dioxide by using a modified sol-gel method. The synthesis process involved supercritical drying of ethyl alcohol. The effect of doping on TO sample microstructure, optical and electrical properties was studied, which is crucial to understanding its potential applications. The X-ray diffraction pattern reveals that the nanoparticles crystallized in the tetragonal rutile structure with a size varying from 22 to 25 nm depending on element doping. The structural analysis was further proved by Raman spectroscopy and FTIR investigations. The optical band gap energy decreases upon the doping, as evidenced by the Eg values of 3.88, 3.87, and 3.72 eV corresponding to, FTO, and ATO respectively. This result proves that our compounds are good candidates for optoelectronic applications. Further, the electrical properties proved the semiconductor behavior for all the samples. Its conductivity is thermally activated, with a decrease in activation energy observed upon the addition of dopants. Moreover, the temperature dependence of the exponents's'of the (ac) conductivity proves that the conduction mechanism varies with dopants. The decrease of s values for undoped and FTO samples revealed a dominant correlated barrier hopping, while the increase of 's' for ATO confirmed the tunneling hopping mechanism. Furthermore, the representation of real and imaginary parts of impedance has also been analyzed. Thus, the obtained results open exciting opportunities for using these samples in many fields that foster the combination of optical and electrical properties.