Abstract
We introduce the first pi-conjugated polymer-based, black-to-transmissive and multicolored switching electrochromic device (ECD) Constructed in a Pseudo 3-Electrode Electrochromic Device (P3-ECD) architecture. In this ECD, the non-electrochromic, yet electroactive, polymer poly(3,4-propylenedioxypyrrole-N-propionitrile) (PProDOP-N-EtCN) serves as a counter electrode material. This transmissive polymer help,; eliminate the contrast limitations seen in dual polymer ECDs that use combinations of anodically and cathodically coloring polymers. The P3-ECD adds colors by transmitting light through two independently Controlled working electrodes (coated with two different electrochromic polymer films) and two counter electrodes (coated with PProDOP-N-EtCN) stacked together with a gel electrolyte. The two cathodically coloring EC polymers that were used in this work are, a diester-substituted poly(3,4-propylenedioxythiophene) (PProDOT-(CH2CO2C12H25)(2)) for the first one, namely PProDOT-ester, and a donor-acceptor analogue, namely PProDOT-BTD, which consists of a specific alternation of donor and acceptor building units spanning the electron-rich 3,4-ethylenedioxythiophene (EDOT), 2-ethylhexyloxy-substituted 3,4-propylenedioxythiophere ProDOT(CH2O(2-EtHX))(2) and the electron-deficient 2,1,3-benzothiadrazole (BTD). The ProDOT-ester switches from a deep purple (L* = 41 a* = 22 b* = -48) to it highly transmissive gray/bluc (L* = 87 a* = -2b* = -7), while the PProDOT-BTD switches from a deep green (L* = 60, a* = -23, b* = 12) to transmissive sky blue (L* = 84, a* = -4, b* = -6). Utilizing PProDOT-ester and PProDOT-BTD in their neutral form in the P3-ECD yields a deep blue-black with color coordinates of L* = 26,a* = -3,b* = -17 switching to a transmissive state with color coordinates of L* = 75,a* = -7,b* = -7. The device has a high Michelson contrast of 0.8 (which can range from 0 to 1). Separate potential control over the electrodes allows color mixing of the polymers in intermediate oxidation states in the P3-ECD. As such, it full palette of colors is accessible through proper choice of EC materia Is as desired for the construction of multicolored information displays, and in the case of black-to-transmissive electronic paper