A single-molecule multicolor electrochromic device generated through medium engineering

Abstract

Multicolor organic electrochromic materials are important for the generation of full-color devices. However, achieving multiple colors using a single-molecule material has proved challenging. In this study, a multicolor electrochromic prototype device is generated by integrating medium engineering/in situ 'electro base'/laminated electrode technologies with the simple flying fish-shaped methyl ketone TM1. This multicolor electrochromic (green, blue and magenta) device is durable and has a high coloration efficiency (350 cm 2 C 21 ), a fast switching time (50 ms) and superior reversibility. This study is a successful attempt to integrate solvatochromism and basochromism in an electronic display. This integration not only introduces a new avenue for color tuning, in addition to the structural design of the colorant, but will also inspire further developments in the tuning of many other properties by this medium engineering approach, such as conductance and the redox property, and thereby accelerate versatile applications in data recording, ultrathin flexible displays, and optical communication and sensing. Keywords: electrochromic materials; laminated electrodes; microenvironment; multicolor devices; solvatochromic materials INTRODUCTION Owing to the increasing demand for low-power, ultrathin, flexible electronic displays, organic electrochromic materials 1-3 have become a research focus because of their distinct merits: low weight, high contrast, wide viewing angle, flexibility and the potential for low power consumption. Because the realization of a multicolor switch is preferred in the majority of their applications in displays, 4-10 various electrochromic materials including polymers, 11,12 small organic molecules 13,14 and metal-organic complexes, 15 and technologies aimed at multicolor switches have been intensively explored. Transition metals based on metal-organic complex multicolor electrochromic materials exhibit attractive properties, such as high stability and chemiluminescence. 16 However, the expense and scarcity of the precious metals, such as ruthenium, 15,16 osmium 17 and iridium, 18 limit their practical applications. Polymeric multicolor electrochromic materials with different electrochromic activation units [19][20][21] possess the advantages of easy processing, diverse resources and facile color tunability. However, some intrinsic problems, such as the lack of colorless states, poor transparency, poor color purity and complicated synthesis procedures, hinder their applications. Compared with electrochromic polymers, small organic color switches possess the advantages of low cost, good color purity, distinct transition from colorless to colored states and fine tunability of their photoelectronic properties via easy structure modifications. The lack of multicolor abilities is their intrinsic

Robust Triplatinum Redox‐Chromophore for a Post‐Synthetic Color‐Tunable Electrochromic System

“…2.8-3.4 ), [11] but slightly longer than those previously reportedf or triple-decker Pt II (bpy) complexes bridged by substituted naphthyridine ligands (2.77-2.81 ;s ee Table S1). [12] Long Pt···Pt distances (3.7481(8)a nd 4.4582 (8) )b etween the molecules are indicative of negligible intermolecularP t ···Pt interactions ( Figure S2). Pt 3 (+ 2) exhibited ap ale-green color in solution and am oderately intense broad absorption band with am aximum at 621 nm (e = 3.6 10 3 m À1 cm À1 )( Figure 3d-i and FigureS3, Supporting Information).…”

“…Post-synthetic color-tuning is expected to be one of the most efficient strategiesf or achieving easily color-tunable electrochromic redox-chromophores. [8] For typical electrochromic metal complexes, color-tuning can be achieved by applying ligand modifications and/or the replacement of metal ions (i.e., synthetic color-tuning strategies). [4] In contrast to these systems, as shown in Figure 1, the electron removal and injection processes of multi-decker platinum complexes can be coupled with the coordination/dissociation of axial ligands.…”

A Multi‐Stimuli‐Responsive Oxazine Molecular Switch: A Strategy for the Design of Electrochromic Materials

“…As showni nF igure 3, the first reductive peak of M-c is at À1.0 V. According to the LUMO of M-c as calculated by using DFT (see Figure S6), this peak is presumed to come from the reduction of the nitro group of the p-nitrophenolp art due to its strong electron-withdrawing property. The reduced state of the nitro group has alkalinity, [45,46] which may be used to control the base-sensitive color change of M-c,asw ee xpected. The slight difference in the reduction peaks may come from the different CÀO and HÀOg roups of M-c and p-nitrophenol, and also may come from the spatiale lectron density influence of the indole part.…”

“…However,t he application of pHsensitivem olecular switches in ECM is hindered by the lack of an electrical response ability. [45][46][47] Electro-acids/bases (e.g., pphenylenediamine and benzoquinone) are at ype of molecule in which the oxidative or reductives tate is able to captureo r lose ap roton. [45][46][47] Electro-acids/bases (e.g., pphenylenediamine and benzoquinone) are at ype of molecule in which the oxidative or reductives tate is able to captureo r lose ap roton.…”

“…[42][43][44] An "electro-acid/base" was used by our group to extend the application of pH-sensitive molecular switches into ECM. [45][46][47] Electro-acids/bases (e.g., pphenylenediamine and benzoquinone) are at ype of molecule in which the oxidative or reductives tate is able to captureo r lose ap roton. Compared with chemical acids/bases,t he acidity or alkalinity of the electro-acid/base can be controlled by an externale lectric field in ac losed system.B yu sing these electro-acid/base molecules, variousp H-sensitive molecular switches with possible applications in ECM were obtained.…”