Low‐Voltage Electrically Responsive Photonic Crystal Based on Weak‐Polar Colloidal System

Abstract

Electrically responsive photonic crystal (ERPC) based on particle electrophoresis is a promising material to construct reflective color displays with low‐power‐consumption and antiglare advantages. However, the high driving voltages for the polar ERPC inevitably cause electrochemical reactions on the electrode, which decreases the stability and reversibility of electrical response. Here, a weak‐polar EPRC composed of hydrophobic SiO2 particles, 1,2‐dichlorobenzene (DCB), and dioctyl sulfosuccinate sodium salt (AOT) is fabricated based on the charge separation by AOT reverse micelles and formation of highly charged particles in DCB. Compared to the polar ERPCs, the SiO2/DCB‐AOT ERPC works at much lower voltages (0.5–1.7 V) and still possesses a wide color tuning range because the weak‐polar solvent applies less screening to the coulombic interactions. The low potential further renders the ERPC good capability against color fading in a strong field and long‐term reversibility during color switching, which addresses the critical concerns for its application in reflective displays.

Low-voltage and wide-tuning-range SiO2/aniline electrically responsive photonic crystal fabricated by solvent assisted charge separation

“…This is a common limitation for known low-voltage ERPCs. 4 Typically, it took about 45 s and 90 s for the ERPC to achieve its balanced optical signal when a voltage of 0.8 V was directly applied to or withdrawn from the SiO 2 /ANI ERPC (Fig. S13a, ESI †).…”

“…Various stimuli, including electric field, [1][2][3][4][5][6][7] magnetic field, [8][9][10][11] thermal interaction, [12][13][14] mechanical force, [15][16][17] and the chemical environment, [18][19][20][21][22][23][24] are capable of changing the color of photonic crystals. Considering the feasibility of controlling the electric field on a miniaturized scale, an electrically responsive photonic crystal (ERPC) was an ideal system for realizing instant and accurate tuning of colors.…”

“…In earlier work, polar solvents, such as water, 25,34,37 ethylene glycol, 38 and PCb, 1,26,33,[39][40][41][42] were selected to construct the ERPC because the particles were well dispersed in these solvents and a high surface charge on the particles was easier to achieve, 43,44 although the Coulombic interaction was screened. Recently, weak polar ERPCs in 1,2-dichlorobenzene (DCB) or Isopar G-halocarbon oil (IPG-HC) were fabricated, 4,5,45,46 where the solvents applied less screening to the Coulombic interaction, leading to low working potential, a broad color tuning range, and good stability under electric fields. Although weak polar ERPCs achieved an improved performance, their synthesis was not easy.…”

Highly Stable Microcapsules of Colloidal Photonic Ink in Nonpolar Medium for Full Color E‐Skin Device

“…[11] Ge and co-workers recently reported that a weak-polar medium can enhance voltage response of electrically responsive photonic crystal. [12] They also investigated a bistable EPD which is suitable for a low-power consumption display. [13] Microencapsulation of particle dispersion is a prerequisite to expediting the commercialization of color EPD, as the microcapsule (μ-capsule) is an ideal form for the EPD material, which can be coated on the transparent electrode with no leakage concern.…”

“…[ 11 ] Ge and co‐workers recently reported that a weak‐polar medium can enhance voltage response of electrically responsive photonic crystal. [ 12 ] They also investigated a bistable EPD which is suitable for a low‐power consumption display. [ 13 ]…”