Structure correlated optoelectronic and electrochemical properties of Al/Li modified ZnO

Abstract

ZnO with novel optoelectronic properties has been considered as a potential candidate for supercapacitor applications. In this study, a varying content ratio of Al3+ and Li1+ is incorporated in ZnO, and its influence on various physical and electronic properties has been explored. Rietveld analysis reveals that all samples crystallize in the wurtzite structure with the P63mc space group. Additional Li1+ doping in Al3+ substituted ZnO results in variations in lattice parameters, bandgap, and crystalline nature with increasing Li1+ content. Photoluminescence studies indicate that oxygen vacancies decrease and oxygen richness increases as Li is introduced nominally (x = 0.125) in Al-doped ZnO; but, with the further addition of Li, the oxygen content decreases resulting in enhanced green emission. Interestingly, no near band emission is observed in codoped samples suggesting a defected lattice. The addition of a nominal amount of Li1+ (x = 0.125) shows enhanced electrochemical performance with higher specific capacitance. All samples show quasireversible behavior. A correlation among lattice parameters, strain, bandgap, oxygen and dopant related defects, and electrochemical properties is established. © 2019 Author(s).