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The size and spectral dependence of the persistent photocurrent (PPC) of dc sputtered indium oxide (IO) films has been studied under UV and sub-band gap illuminations. PPC follows bi-exponential decay with a fast and a slow process having time constants (denoted by τ f and τ s, respectively) that differ by about two orders of magnitude. τ s is associated with carrier scattering from an initial surface state to a surface or bulk state with the former dominating below a characteristic length scale of ∼60 nm. On the other hand, τ f is characterized by the process where both the initial and final states are surface related. Treating the IO film surface with tetramethyl tetraphenyl trisiloxane (TTTS) decreases τ s by a factor of 5 with τ f remaining almost unaffected, which is a clear indication of reduction of defects specific to the slow relaxation process. Based on the molecular structure and chemical activity of TTTS, it is suggested that TTTS may passivate mainly the dangling oxygen-bonds at the film surf...

Photochromic transitions in silvernanoparticles (AgNPs) embedded titanium dioxide (TiO2) films under green light illumination are marked by reduction in strength and blue shift in the position of the localized surface plasmon resonance (LSPR) associated with AgNPs. These transitions, which happen in the sub-nanometer length scale, have been analysed using the variations observed in the effective dielectric properties of the Ag-TiO2nanocompositefilms in response to the size reduction of AgNPs and subsequent changes in the surrounding medium due to photo-oxidation. Bergman-Milton formulation based on spectral density approach is used to extract dielectric properties and information about the geometrical distribution of the effective medium. Combined with finite element method simulations, we isolate the effects due to the change in average size of the nanoparticles and those due to the change in the dielectric function of the surrounding medium. By analysing the dynamics of photochromic transitions in the effective medium, we conclude that the observed blue shift in LSPR is mainly because of the change in the dielectric function of surrounding medium, while a shape-preserving effective size reduction of the AgNPs causes decrease in the strength of LSPR.