title: Color purity in polymer electrochromic window devices on indium-tin oxide and single-walled carbon nanotube electrodes.
abstract: Dual polymer absorptive/transmissive electrochromic (EC) window devices have been assembled using the solution-processable and high-EC-contrast polymer PProDOT-(CH(2)OEtHx)(2) as the EC material, along with a non-color-changing electroactive polymer, poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl methacrylate) (PTMA), as the counter electrode material. Indium-tin oxide (ITO) and highly transmissive single-walled carbon nanotube (SWNT) film coated glass electrodes are used as electrode substrates. The use of the EC/non-color-changing polymer combination allowed us to construct window devices that rapidly switch between magenta and highly transmissive (>95% T for ITO and approximately 79% T for SWNT) states with large optical modulation (>71% DeltaT for ITO and 66% DeltaT for SWNT). The devices showed effective coloration and bleaching: the lightness parameter (L*) changing from 67 to 95 for ITO (approximately 50-92 for SWNT), essentially reaching a diffuse white upon oxidation. The color modulates from highly pure magenta with a* = 28 (red hue) and b* = -28 (blue chroma) for ITO (a* = 40 and b* = -36 for SWNT) to nearly colorless with a* = 1 and b* = -1 for ITO (a* = -2 and b* = -3 for SWNT) devices. Increasing the switching voltage from 2.55 V up to 3.5 V resulted in faster SWNT-based window device performance.
authors.affiliation: The George and Josephine Butler Polymer Research Laboratory, Department of Chemistry, Center for Macromolecular Science and Engineering, University of Florida, Gainesville, Florida 32611-7200, USA.
authors.forename: Svetlana V
authors.initials: SV
authors.lastname: Vasilyeva
authors.forename: Ece
authors.initials: E
authors.lastname: Unur
authors.forename: Ryan M
authors.initials: RM
authors.lastname: Walczak
authors.forename: Evan P
authors.initials: EP
authors.lastname: Donoghue
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Rinzler
authors.forename: John R
authors.initials: JR
authors.lastname: Reynolds