Enhancing charge transport and photoluminescence characteristics via transition metals doping in ITO thin films

Abstract

This study presents the synthesis and characterization of pristine and transition metal (Co, Fe, and Zr)-doped indium tin oxide (ITO) thin films fabricated via RF magnetron sputtering. The effect of transition metal doping on ITO thin films properties was comprehensively examined using numerous spectroscopic and microscopic methods such as XRD, FTIR, and SEM coupled with EDX, UV–visible and PL spectroscopy, and four-probe and J–V measurements. The cubic crystal structure of the materials was confirmed through XRD spectroscopy, while FTIR results validated the existence of chemical bonds, signified by sharp peaks at 608 cm−1 and 667 cm−1 in the fingerprint region. SEM imaging revealed a granular-like agglomerated structure, with EDX confirming the elemental composition of the samples. The incorporation of Co, Fe, and Zr ions into ITO is aimed at improving photoconductivity and the optical bandgap, with the ultimate objective of enhancing performance in photovoltaic applications. Our findings showed a significant decrease in optical transmission in the visible spectrum. The bandgap also experienced a minor decrease from 3.67 eV to 3.53 eV. Analysis of the photoluminescence spectra exhibited the majority of emission peaks in the UV region, ascribed to electronic transitions occurring via band-to-band and band-to-impurity interactions within the ITO. Electrical measurements indicated lower resistance, higher current flow, and increased carrier concentration in transition metals–doped ITO compared to the undoped ITO, with Zr-doped ITO exhibiting the highest conductivity and optimal charge flow among all dopants. These promising findings in terms of optical, structural, and electrical attributes signal the potential of these materials for photovoltaic system applications.