Exciton Dynamics and Effects of Structural Order in Morphology‐Controlled J‐Aggregate Assemblies

Abstract

Narrow-band photoluminescence (PL) together with high quantum efficiency from organic molecules is essential for high color purity emitters. Supramolecular assemblies like Jaggregates are promising materials due to their narrow PL signal with full-width at half maximum (FWHM) < 20 nm. However, their micro-crystalline nature and coherent exciton migration results in strong non-radiative exciton recombination at the grain boundaries that diminish the photoluminescence quantum yield (PLQY), and possibilities for improving the crystallinity by tuning the growth mechanism were limited. Here, we demonstrate two distinct routes to grow different J-aggregate morphologies like platelets and lamellar crystals with Received: ((will be filled in by the editorial staff))Revised: ((will be filled in by the editorial staff))

Exploiting supramolecular assemblies for filterless ultra-narrowband organic photodetectors with inkjet fabrication capability

“…Two of these dyes are already known to form J-aggregates in solution. The J580 dye is well-known to form J-aggregates in water 47,48 , which is not the case for the J780 dye that forms undesired H-aggregates in this solvent. However, upon addition of sodium chloride Jaggregation can be induced for the J780 dye.…”

“…(d) Comparison of attenuance peaks of aggregate thin films when suspended aggregates are directly deposited from solution (solid line) or obtained in-situ during spin-coating from a monomer solution (dotted line) on ITO/TiO2 substrate.One recurring challenge in fabricating organic thin film devices is to produce high quality thin films with low roughness and a minimum number of defects like pinholes, grain boundaries or crystal interfaces. This is particularly challenging in our case, since J-aggregates consist of two-dimensional platelets complicating the realization of a continuous surface coverage 48. A number of methods are known which are susceptible to form homogeneous and continuous films.…”

Excitonic channels from bio-inspired templated supramolecular assembly of J-aggregate nanowires

“…dendrimers cannot be recognized. 18,42 Imprints of the DP monolayer are visible in the J-aggregate crystal, but a direct guiding or templating effect of the substrate is not apparent. Also, this process was independent of DP generation and dye solution concentration.…”

“…† The aggregates adsorbed from solution crystallized into larger objects following a Volmer-Weber growth model and did not form conformal coatings on the DPs. 18 A crystal morphology of this type is characteristic for J-aggregates deposited onto functionalised substrates, and a direct advantage of using DPs over e.g. dendrimers cannot be recognized.…”

“…5,8 Despite extensive research into tubular J-aggregates, [8][9][10][11][12][13][14][15][16] they are scarce and tuning the morphology of J-aggregate remains challenging. 9,17,18 Given these structural restrictions, it is challenging to modify optical properties without impacting J-aggregate morphology, limiting applications in devices relying on exciton transport. Furthermore, J-aggregates are generally poorly soluble independent of morphology and processing into thin films can be a challenge.…”