Surface defect-related luminescence properties of SnO₂ nanorods and nanoparticles

Abstract

We demonstrate the surface defect-related luminescence properties of SnO₂ nanorods and nanoparticles using steady-state and time-resolved spectroscopy. Defect-related bands are identified by Raman and EPR spectroscopy. On the basis of the experimental results, we propose a schematic model for different relaxation processes in SnO₂ nanocrystals upon photoexcitation. Analysis suggests that the visible emission of SnO₂ nanocrystals is due to a transition of an electron from a level close to the conduction band edge to a deeply trapped hole in the bulk (V₀^••) of the SnO₂ nanocrystals. Analysis suggests that the surface-related defects are more prominent in smaller nanocrystals than in nanorods. It is found that the PL emission and decay time strongly depend on the shape of the nanocrystals. This proposed model is further confirmed by time-resolved spectroscopy.