Electroluminochromic Materials: From Molecules to Polymers

Abstract

Electroluminochromism is an interesting property found in certain classes of molecules and polymers whose photoluminescence can be modulated through the application of an external electrical bias. Unlike electrochromic materials, electroluminochromic counterparts and their applications are comparatively fewer in quantity and are less established. Nonetheless, there prevails an increasing interest in this class of electro-active materials due to their potential applications in optoelectronics, such as smart-displays, and chemical and biological sensing. This review seeks to showcase the different classes of electroluminochromic materials with focus on (i) organic molecules, (ii) transition metal complexes, and (iii) organic polymers. The mechanisms and electroluminochromic performance of these classes of materials are summarized. This review should allow scientists to have a better and deeper understanding of materials design strategies and, more importantly, structure-property relationships and, thus, develops electroluminochromic materials with desired performance in the future.

Overview on the Recent Progress on Electrofluorochromic Materials and Devices: A Critical Synopsis

“…This electroluminochromic effect is important and can be used to control the color of the emitted light, too. [19,62,92] The exceptional properties of compound I have been exploited in all-in-one single layer devices, [33] where the electrofluorochromic layer was formed by polymer gels incorporating different amounts of the mixed valence compound, where the C 6 H 13 chains are replaced with the C 5 H 11 O 2 chains (1% to 10% (w/w)), as anodic component and ethylviologen perchlorate as cathodic one. The EFC MV IV in the gel preserves its high photoluminescence quantum yield (63%) by restriction of the intramolecular motions in the more viscous device environment, despite its concentration ranged from (10 −3 -10 −2 m), thus no significant ACQ occurs.…”

“…The aggregation-caused quenching, also in this contest, is the main drawback as by Montilla et al [93] and as widely discussed in a few reviews on polymeric electrofluorochromic materials reported so far. [19,29,94] For example, this problem is often found in polythiophenes and polypyrroles base polymers due to their high planarity. Usually, these polymers are good emitters in dilute solution but very weak in solid state.…”

“…This is mainly observed in metal organic complexes based on metals with d 6 , d 8 , and d 10 configuration such as Ir III , Ru II , and Eu III that, in contrast to entirely organic systems, exhibit emission lifetimes of several seconds. [ 19,20 ] Metal complexes generally have also rich excited state properties, good redox reversibility, high emission quantum yields, thereby showing electroluminochromic response with multicolor tunable emission in a wide wavelength range. [ 19,20 ] This interesting class of ELC materials has been extensively discussed in a some very recent reviews [ 19,20,21 ] to which the reader is reminded.…”

Electroluminochromic Materials and Devices Based on Metal Complexes

“…ELC behaviors can be achieved by tuning the following processeso fp hotofunctional metal complexes under electric field, including photoinduced electron transfer (PeT), Fçrster resonance energy transfer (FRET), redox states, and ion migration. [39][40][41] PeT and FRET mechanisms are primarily applied to the conjugated or non-conjugated dyads or triads, which consist of a redox-active moiety and al uminophore linked either directly or throughabridge. The redox-actives egmentc an induce the occurrence of electrochemical reaction,i nfluencing the PeT or FRET process and resulting in the change of emissionp roperties of luminophore.…”

Solution‐Processable Copolymers Based on Triphenylamine and 3,4‐Ethylenedioxythiophene: Facile Synthesis and Multielectrochromism

“…[ 6–9 ] In the event of changes to fluorescence color and intensity occurring as well, these materials can be said to also exhibit electrofluorochromic properties. [ 10–12 ] In general, color switching in EC materials can occur reversibly between i) a transmissive and a colored state, ii) two colored states, or iii) multiple colored states, which can be termed polyelectrochromism or multielectrochromism. [ 5 ] The development of EC materials and engineering of EC devices have gained significant research interest over the past years, due to the EC technology offering many useful applications, such as smart windows, antiglare rear‐view mirrors, optical displays, and military camouflage paints, some of which have been commercialized.…”