ZnO-Doped Tin-Based Oxides P-Type Transparent Conductive Oxides for Solar-Cell Electrodes

The demand for clean energy is rapidly expanding the market of solar panels. Transparent conductive oxide (TCO) materials allow light to pass through a solar cell while efficiently conducting the electricity generated within a device without sacrificing light absorption due to using opaque metal wires as electrodes to collect currents. As a result, TCOs surpass metal wires in efficiency when used as solar cell electrodes. Furthermore, they exhibit excellent chemical stability and durability, enabling long-term stable operation under various environmental conditions. Therefore, using TCOs as solar cell electrodes is a promising approach to drive further development and application for solar energy technology.<br/><br/>This work focuses on developing p-type TCOs using ZnO-doped tin-based oxides. These materials are chosen for their high bandgap and suitable valence difference to achieve p-type carrier conductivity. Zinc oxide is used as a dopant to replace high-valence elements, thereby increasing hole concentration to improve electrical conductivity. The fabrication process involves forming the sputtering targets of ZnO-doped tin-based oxides through solid-state sintering. Subsequently, ZnO-doped tin-based oxide thin films are deposited on glass substrates using radio-frequency (RF) magnetron sputtering. Those films are then annealed under various conditions to optimize their electrical conductivity and transparency.<br/><br/>The crystal structure of ZnO-doped tin-based oxides is analyzed with an X-ray diffractometer (XRD). Their morphology and composition are examined by scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDX), respectively. The optical transparency properties of ZnO-doped tin-based oxide thin films are analyzed by a UV-visible (UV-Vis) spectrophotometer. Four-point probes are used to analyze the resistivity of materials. This work aims to provide novel ZnO-doped tin-based oxide materials for p-type TCOs as potential electrodes for solar cells.