Morphological and Electrical Characterization of ZnO Co-Doped with Al and B Via Sol-Gel for Window Layer Applications in Solar Cells

This paper presents the synthesis and characterization of zinc oxide (ZnO) films co-doped with aluminum (Al) and boron (B) via sol-gel method for use as a window layer in photovoltaic devices. The morphology of the particles, degree of crystallinity, and size distribution of the ZnO particles are critical parameters to window layer performance, and were examined by high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED). The electrical properties of the films were assessed using the Hall Effect method. As a result, the film's resistivity of 3.18 x 10-4,,  carrier concentration of 6.2 x 1020 and the mobility of 31.7 cm2/V•s demonstrated that the charge transport properties of the ZnO:Al:B films were comparable to high-quality indium tin oxide (ITO). Based on HRTEM analysis, the particle size of undoped ZnO is 24.40 nm, but decreases for ZnO:Al, ZnO:B, and ZnO:B:Al to 20.48 nm, 23.83 nm, and 17.30 nm respectively. ZnO:Al:B co-doped thin film can be considered a viable alternative to ITO in photovoltaic solar cell applications, offering comparable electrical performance with the added advantages of lower material cost and greater elemental abundance.