Molecular Engineering Approaches Towards All‐Organic White Light Emitting Materials

Abstract

White light emitting (WLE) materials are of increasing interesto wing to their promising applicationsi na rtificial lighting, display devices, molecular sensors, and switches.I n this context,o rganic WLE materials cater to the interesto f the scientific community owing to their promising features like color purity,l ong-term stability,s olutionp rocessability, cost-effectiveness,a nd low toxicity.T he typical methodf or the generation of white light is to combine three primary (red, green, and blue) or the two complementary (e.g., yellow and blue or red and cyan) emissive units covering the whole visible spectralw indow (400-800 nm). The judicious choice of molecular buildingb locks and connecting them through either strong covalentb onds or assembling through weakn oncovalent interactions are the key to achieve enhanced emissions panning the entire visible region.In the present review article, moleculare ngineering approaches for the development of all-organic WLE materials are analyzed in view of different photophysical processes like fluorescencer esonance energy transfer (FRET), excitedstate intramolecular protont ransfer (ESIPT), charget ransfer (CT), monomer-excimer emission, triplet-state harvesting, etc. The key aspect of tuning the molecular fluorescence under the influence of pH, heat, and host-guest interactions is also discussed. The white light emission obtained from small organic molecules to supramolecular assemblies is presented,i ncluding polymers, micelles,a nd also employing covalent organic frameworks. The state-of-the-art knowledge in the field of organic WLE materials, challenges, and future scope are delineated.

Fundamental Aspects of Xanthene Dye Aggregation on the Surfaces of Nanocluster Polyoxometalates: H‐ to J‐Aggregate Switching

“…Caused by its molecular structure, the aggregation behavior of the sensitizer is one of the most important features in determining the general efficiency of the photochemical process. Therefore, to achieve the best result, the aggregation of a sensitizer needs to be controlled . In addition to photovoltaics, there is the aggregation‐induced emission (AIE) phenomenon; here, the self‐assembly of dye molecules is the main requirement for tuning fluorescent properties .…”

Recent Advances in Mechanochromic Luminescence of Organic Crystalline Compounds

“…However, the design and fabrication of white-light-emissive single molecules still remain a challenging task. 61,62 In 2020, Murai and coworkers demonstrated the whitelight emission from multi-stimuli-responsive N,N-diarylthiazole-5-amine derivative 30 (Figure 7h). 63 Although only a slight change in the emission properties was observed by grinding pristine orange-emissive solid of 30, the emission color of the ground sample significantly changed to white (CIE coordinate: 0.32, 0.33) upon fuming with acetone.…”

Rare Earth‐Free Luminescent Materials for WLEDs: Recent Progress and Perspectives

“…Some comprehensive summaries of the preparation methods and luminescence mechanisms of organic white light-emitting materials are available. [106,107] LED light conversion materials are one of the important applications of organic white light materials. Additionally, many organic materials have been successfully applied to rare earth-free WLEDs.…”