Executive Summary : | The significant rise in the demand of high-performance transparent conducting oxides (TCOs) as top electrodes in optical detectors, solar cells and LEDs, of late, is due to the rapidly increasing sector of next-generation smart electronics. However, the challenge in screening an efficient transparent conductor lies in finding materials with high optical transparency and high electrical conductivity. Heavily doped wide bandgap semiconductor oxides such as indium tin oxide (ITO), are generally used as transparent conductors. However, the major bottlenecks in mass-scale commercialization of these devices are the high cost and scarcity of Indium and the fragility and inability of ITO-coated substrates to withstand high temperature. The other wide gaped semiconductors used in the visible spectra suffer from insufficient electrical conductivity and the synthesis of thin films possessing both high electrical conductivity as well as optical transparency has been proven to be very challenging. Motivated by the alternate design strategy that relies on strong electron interactions and the subsequent enhancement of the carrier effective mass in a material, this project intends to explore Strontium-based perovskites (SrMO₃, M=V, Nb, W) as potential TCOs. Forcing a correlated material close to the metal-insulator transition (MIT) where the carriers will possess enhanced effective mass albeit retaining the conducting nature is the key in this approach and has already been experimentally verified for SrVO₃. Although several studies on SrVO₃ and a very few on SrNbO₃ have projected them to be potential TCs, how to drive the compounds near MIT through is still unexplored and is necessary to use them in top electrodes. In addition, SrWO3 sharing similar electronic structure as SrVO₃ and SrNbO₃ (partially filled d band) is the least explored TC material, till date. High energy implantation of Cu, Ni, Fe dopants in a host provides the user with precise control over the concentration and targeted doping and helps altering the hosts’ electronic structure significantly. Previous studies in similar strongly correlated metals such as LaNiO₃ have also shown that while oxygen vacancy drives the system closer to the MIT, application of strain can result in enhanced carrier mobility in the material. Employing a combination of density functional theory (DFT) and the semiclassical Boltzmann transport theory, this project aims to explore the role of (i) doping via ion-implantation (ii) incorporation of oxygen vacancy and (iii) application of external strain in modulating the degree of strong electronic correlation in the SrMO3 compounds. The extent of these modulations will be realized through changes in the electronic structure, optical and transport properties, effective mass of charge carriers and plasma frequency of all the SrMO₃ compounds, which in turn will unravel the ways to the rational design of low cost and highly performance TCO materials. |