Tailoring ZnO Emission for UV Devices: Enhanced Photoluminescence through Thiophenol Surface Capping

In this research, the optical characteristics of ZnO nanoparticles modified with 4-aminothiophenol were thoroughly examined. The surface modification was achieved through colloidal synthesis, employing a wet chemical precipitation method with carefully selected precursors. The attachment of 4-aminothiophenol molecules to the ZnO nanoparticle surfaces resulted in significant changes to their optical behaviour. These surface-modified nanoparticles were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier-transform infrared (FTIR) spectroscopy. Optical analysis was conducted using UV-Visible absorption and photoluminescence (PL) spectroscopy. The study focused on understanding the underlying mechanisms behind the observed changes in fluorescence and absorption properties. Notably, the surface capping led to a marked enhancement of near-band-edge ultraviolet (UV) emission and a significant suppression of the defect-related green luminescence in the PL spectra. This enhancement indicates that surface defects, such as oxygen vacancies, were effectively passivated by the capping agent. The improved optical performance highlights the potential of these modified ZnO nanoparticles for advanced optoelectronic applications, including UV lasers and LEDs. Overall, the use of 4-aminothiophenol as a capping agent was shown to play a critical role in tuning the optical properties of ZnO nanoparticles.