Supramolecularly Engineered J-Aggregates Based on Perylene Bisimide Dyes

Abstract

Conspectus The discovery of the self-assembly of cyanine dyes into J-aggregates had a major impact on the development of dye chemistry due to the emergence of new useful properties in the aggregated state. The unique optical features of these J-aggregates are narrowed, bathochromically shifted absorption bands with almost resonant fluorescence with an increased radiative rate that results from the coherently coupled molecular transition dipoles arranged in a slip-stacked fashion. Because of their desirable properties, J-aggregates gained popularity in the field of functional materials and enabled the efficient photosensitization of silver halide grains in color photography. However, despite a good theoretical understanding of structure–property relationships by the molecular exciton model, further examples of J-aggregates remained scarce for a long time as supramolecular designs to guide the formation of dye aggregates into the required slip-stacked arrangement were lacking. Drawing inspiration from the bacteriochlorophyll c self-organization found in the chlorosomal light-harvesting antennas of green sulfur bacteria, we envisioned the use of nature’s supramolecular blueprint to develop J-aggregates of perylene bisimides (PBIs). This class of materials is applied in high-performance color pigments and as n-type organic semiconductors in transistors and solar cells. Combining outstanding photochemical and thermal stability, high tinctorial strength and excellent fluorescence, PBIs are therefore an ideal model system for the preparation of J-aggregates with a wide range of potential applications. In this Account, we elucidate how a combination of steric constraints and hydrogen bonding receptor sites can guide the self-assembly of PBI dyes into slip-stacked packing motifs with J-type exciton coupling. We will discuss the supramolecular polymerization of multiple hydrogen-bonded PBI strands in organic and aqueous media and how minor structural modifications in monomeric PBI molecules can be used to obtain near-infrared absorbing J-aggregates, organogels, or thermoresponsive hydrogels. Pushing the boundaries of self-assembly into the bulk, engineering of the substituents’ steric requirements by a dendron-wedge approach afforded adjustable numbers of helical strands of PBI J-aggregates in the columnar liquid-crystalline state and the preparation of lamellar phases. To fully explore their potential, we have studied PBI J-aggregates in collaborative work with spectroscopists, physicists, and theoreticians. In this way, exciton migration over distances of up to 180 nm was shown, and insights into the influence of static disorder on the transport of excitation energy in PBI J-aggregates were derived. Furthermore, the application of PBI J-aggregates as functional materials was demonstrated in photonic microcavities, thin-film transistors, and organic solar cells.

Luminescence in Crystalline Organic Materials: From Molecules to Molecular Solids

“…[ 126,147 ] Furthermore, 1D and 2D J‐type arrangements with pronounced V ex were reported for PDIs, see Table 2. [ 103,116,159,275,276 ] In all these cases, however, the relative strength of the exciton coupling is rather moderate, i.e., in the range of F ex ≈ 2. Here, F ex is defined as [ 38–40,92 ] …”

“…[ 273 ] H‐aggregation is usually less pronounced compared to DSB due to a smaller oscillator strength ( f 01,PDI ≈ 1.0), see Table 1 . On the other hand, J‐aggregation is more frequent and pronounced due to possible multiple 2D interactions, [ 103,116 ] see Table 2 . Hence, the comparison of different substituent patterns in DSB and PDI chromophores underlines the need for knowing the exact intermolecular arrangement to gain understanding of its impact on the spectroscopic properties of molecular solids, as discussed in the following.…”

“…[ 269 ] On the other hand, in J‐aggregates (Table 2), bathochromic shifts in absorption can reach −0.25 eV for merocyanines, [ 278 ] and up to −0.36 eV for cyanine‐ [ 277 ] and PDI‐based dyes. [ 116,275,276 ] Emission shifts in J‐aggregates can equally amount about −0.3 eV, [ 116 ] but can reach large values in H‐aggregates with up to −0.8 eV in fluorinated DSB (Figure 8c), here due to pronounced excimeric contributions. It is noted that solid state emission shifts are usually bathochromic, whereas hypsochromic shifts are rather uncommon.…”

Impact of Fluoroalkylation on the n-Type Charge Transport of Two Naphthodithiophene Diimide Derivatives

“…Small molecule and polymeric n-type organic semiconductors are of great significance for the development of p–n diodes, organic field effect transistors (OFETs), thermoelectric organic devices, complementary circuits, and other plastic electronic devices [ 1 , 2 , 3 , 4 , 5 , 6 ]. Among the promising electron-deficient π-building blocks, dithienocoronenediimide [ 7 ], isoindigo derivatives [ 8 ], perylene diimide derivatives (PDI), [ 9 , 10 , 11 , 12 , 13 ] and diketopyrrolopyrrole [ 14 , 15 ] have been reported. Naphthalene diimide (NDI) was reported in 2000 [ 16 ] as a high-performance n-type semiconductor, and since then, several NDI derivatives have been designed to develop materials for dyes, pigments, sensors, and optoelectronic applications [ 13 , 17 , 18 , 19 , 20 , 21 , 22 ].…”

“…Among the promising electron-deficient π-building blocks, dithienocoronenediimide [ 7 ], isoindigo derivatives [ 8 ], perylene diimide derivatives (PDI), [ 9 , 10 , 11 , 12 , 13 ] and diketopyrrolopyrrole [ 14 , 15 ] have been reported. Naphthalene diimide (NDI) was reported in 2000 [ 16 ] as a high-performance n-type semiconductor, and since then, several NDI derivatives have been designed to develop materials for dyes, pigments, sensors, and optoelectronic applications [ 13 , 17 , 18 , 19 , 20 , 21 , 22 ]. While core-linked NDI derivatives enabled the first high-mobility electron transport in polymer-based thin film transistors [ 19 , 23 ], a recently emerging class of materials consists of core-extended NDIs that afford rigid π frameworks with distinct molecular and electronic structures compared with the smaller NDIs [ 24 ].…”