A fast-switching light-writable and electric-erasable negative photoelectrochromic cell based on Prussian blue films

Abstract

a b s t r a c tWe report a fast-switching negative photoelectrochromic cell composed of a dye-sensitized nanocrystalline TiO 2 electrode and Prussian blue counter electrode sandwiching a LiI electrolyte. The cell can be bleached under illumination with shorted TiO 2 and Prussian blue electrodes, and re-colored by applying an appropriate external voltage. The photo-bleaching and electric-coloring processes are fast and reversible. A maximum absorbance modulation of 0.44 recorded at 700 nm is obtained between bleached and colored states for the cell when the PB film's thickness is 452 nm. Illuminated under different levels of light intensity or durations of time, the shorted cell shows adjustable optical absorption from 470 to 840 nm. The in-situ transmittance response depicts that the photo-bleaching response is 6.2 s for 70% transmittance change under 100 mW/cm 2 illumination in short circuit configuration, and the re-coloration time is about 600 ms under 2 V bias recorded at 780 nm, with an electrochromic coloration efficiency of 103.4 cm 2 /C. The cell shows a good reversible stability and can be potentially applied in erasable displays.

Electrochromic bilayers of Prussian blue and its Cr analogue

“…The value for Z was found to be 147.8 AE 0.8 cm 2 C À1 , for the blue to bleach process, which is of the same order of magnitude as reported in other studies employing the FeFe PB as part of an electrochromic device. 3,[27][28][29][30] The switching times are defined here as the time taken for 90% of the switch completion. For the blue to bleached state transformation the switching time is 4.4 AE 0.4 s.…”

“…PB and its analogues are coordination polymers comprising transition metal ions linked by cyanide ligands in a rock-salt structure. A wealth of heterostructures exist which contain PB in combination with other materials, such as dye-sensitised titania 3 and conductive polymers. 4,5 There have also been a number of studies that employ multiple Prussian blue analogues (PBAs) to create heterostructures in the form of thin films or nanoparticles to study photoinduced magnetism 6,7 and magneto-structural effects.…”

Performance and stability of “partly covered” photoelectrochromic devices for energy saving and power production

“…Following these early reports, various groups around the world have proposed different PEC device architectures, with alterations to the position of the EC layer (placed at the cathode or the anode), the inclusion of a platinized cathode [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30], the electrical separation of PV and EC elements (also called "photovoltachromic") [31,32] and the use of overlapping regions of WO 3 and Pt at the cathode [32,33].…”

Thermochromic Perovskite Inks for Reversible Smart Window Applications

“…Smart windows are technologically advanced windows that can switch the transmittance of incident light between transparent and opaque states. − This emerging technology reduces the energy consumption of buildings and tailors specific camouflage coatings. The working mechanism of smart windows is related to the materials employed, i.e., electrochromism, thermochromism, photochromism, or gasochromism. − Among these, thermochromics (TCs) attracted broad interest due to their simple reversible mechanism of using thermal energy for switching transmittance. Typically, commercially available TCs are liquid crystals and leuco dyes, and recently vanadium dioxide .…”