Defect induced photoluminescence in SnO₂ nanostructures: Evaluation and Utilization for optical sensing and waveguide application

Despite having an excellent reputation in resistive sensing and profound optical properties, SnO₂ is less explored for optical sensing and waveguide application. In the current project SnO₂ quantum dots [QDs~ 2.4 nm] and 1D NSs [d~500nm], are utilized for photoluminescence (PL) based NH₃ sensing and waveguide application respectively. PL spectra collected from SnO₂ QDs using 325 nm excitation show the rise of peaks at 2.77 and 2.96 eV in the presence of NH₃. Sensor response (R) is calculated in different concentrations of NH_3, (10-500 ppm) using the formula R= (I_gas-I₀)/I₀ [I_gas and I₀, PL intensity in the presence and absence of NH₃]. Defects on the surface of QDs, supported by pre-edge SnM₅ resonance peak in XAS spectrum collected from QDs, form energy band just above the valance band and causes diminished PL peak at 2.77 and 2.96 eV. During the interaction, NH₃ provides electron to SnO₂ and enhance 2.77 and 2.96 eV related transition. Room temperature NH₃ detection with excellent selectivity and high recovery rate ensures the technical importance of this work. Further waveguide application using SnO₂ 1D NSs is realized by exciting single 1-D NSs with 325 nm LASER. Optical images and PL spectra were captured to confirm the defect induced PL is guided through 1D NSs.