From Capacitance-Controlled to Diffusion-Controlled  Electrochromism in Nb-Doped TiO2 Nanocrystalline Electrodes

Monday, 29 May 2017: 15:00
Durham (Hilton New Orleans Riverside)
M. Barawi, R. Da Silva, R. Giannuzzi, L. De Trizio, L. Manna, and M. Manca (Italian Institute of Technology)
A reliable exploitation of localized surface plasmon resonance in transparent conductive oxides is being prospected to push the blooming of a new class of advanced dynamic windows, which offer the unique opportunity to selectively, and dynamically, control the intensity of the incoming thermal radiation without affecting the transparency in the visible range. In this view, Nb-doped TiO2 colloidal nanocrystals are particularly promising as they have a wide bandgap and their plasmonic features can be largely modulated across the near infrared region, by varying the concentration of dopants. Four batches of Nb-doped TiO2 nanocrystals with different doping levels (from 0% to 15% of niobium content) have been used here to produce highly transparent mesoporous electrodes for near-infrared selective electrochromic devices, capable of dynamically modulating the intensity of the transmitted radiation upon the application of a relatively small bias voltage. An engineered dual-band electrochromic device (made of 10%_Nb-doped TiO2 nanocrystals) has been eventually fabricated. Such device was shown to provide two complementary spectroelectrochemical responses, which can be independently controlled through the intensity of the applied potential: a large modulation of the optical transmittance in the near infrared region -via the intensification of the LSPR scattering- is achievable in the 0-3V voltage window, reaching values greater than 64% in the spectral range from 800 to 2000 nm, whereas the visible absorption can be also intensively varied at higher potentials (from 3V to 4V), driven by the consistent Li intercalation into TiO2 anatase lattice