Null Exciton Splitting in Chromophoric Greek Cross (+) Aggregate

Abstract

Exciton interactions in molecular aggregates play ac rucial role in tailoring the optical behaviour of p-conjugated materials.Though vital for optoelectronic applications,i deal Greek cross-dipole (a = 908 8)s tacking of chromophores remains elusive. We report an ovel Greek cross (+ +)a ssembly of 1,7dibromoperylene-3,4,9,10-tetracarboxylic tetrabutylester (PTE-Br 2 )which exhibits null exciton coupling mediated monomer-like optical characteristics in the crystalline state.Incontrast, nonzero exciton coupling in X-type (a = 70.28 8,P TE-Br 0 )a nd J-type (a = 08 8, q = 48.48 8,P TE-Br 4 )a ssemblies have perturbed optical properties.Additionally,the semi-classical Marcus theory of charge-transfer rates predicts aselective hole transport phenomenon in the orthogonally stacked PTE-Br 2 .P recise rotation angle dependent optoelectronic properties in crystalline PTE-Br 2 can have consequences in the rational design of novel p-conjugated materials for photonic and molecular electronic applications. Conflict of interestTheauthors declare no conflict of interest. Figure 3. a) Computed anisotropic mobility along the ac plane and b) schematic depiction of the charge-filtering (selective hole transfer (k h )) phenomenon in PTE-Br 2 Greek cross (+ +)a ggregate.

Crossed 2D versus Slipped 1D π‐Stacking in Polymorphs of Crystalline Organic Thin Films: Impact on the Electronic and Optical Response

“…It should be stressed that only a few crossed stacks were reported in the past, but almost exclusively bearing an 1D stacking motif . On the other hand, 2D crossed π‐stacks—as in the current case—are very rare; in fact, only one example was reported, which exhibited p‐type transport .…”

Protein‐like Enwrapped Perylene Bisimide Chromophore as a Bright Microcrystalline Emitter Material

“…In contrast to previously reported 1,7-diphenoxy-substituted PBI derivatives, [27,28] PBI 1 displays as olid-state fluorescence spectrum that is an almost perfect mirror image of its absorption profile with distinct vibronic progressions at 565, 608, and 663 nm (each separated by 1360 cm À1 ). It is remarkable that even the emission spectrum of PBI 1 in dichloromethane solution is more broadened, less structured, and more red-shifted by 490 cm À1 (Figure 2a nd Supporting Information, Figure S3 a), which hitherto could only be observed for natural pigments (i.e., protein-encapsulated chromophores) [30,31] but not for synthetic pigments.Likewise, the Stokes shift (Dṽ Stokes = 260 cm À1 )and the full width at half maximum (FWHM em = 570 cm À1 )o ft he shortest wavelength emission of microcrystalline PBI 1 is approximately half of that of its monomer emission in solution (Table 1). These observations can be rationalized by ar igidification of the chromophore p-scaffold by its enclosing environment in the solid matrix, thereby preventing structural relaxations of the excited molecules (as well as their environment) as it is given in solution.…”

“…[29] Other recent approaches include the organization of perylene dyes in orthogonally crossed arrangements or at magic angle slipping in which the excitonic coupling vanishes. [30] Interestingly,w hile by these measures solid-state fluorescence quantum yields of up to 59 %c ould indeed be achieved, the absorption and fluorescence spectra of the solid-state materials in all examples still reveal substantial electronic interactions between the PBI dyes whose large p-scaffolds appear to attract each other in sometimes rather unexpected ways with the concomitant deterioration of the fluorescence properties.In this contribution, we report as terically fully enwrapped. [31][32][33][34][35] PBI derivative whose solid-state absorption and emission properties fully match those in solution.…”

Protein‐like Enwrapped Perylene Bisimide Chromophore as a Bright Microcrystalline Emitter Material

“…Because all of these processes are favored by close π–π‐stacking of PBI dyes, much effort has been dedicated to the steric shielding of the chromophore core at imide, headland, or bay positions as well as by isolating individual chromophores in a host matrix . Other recent approaches include the organization of perylene dyes in orthogonally crossed arrangements or at magic angle slipping in which the excitonic coupling vanishes . Interestingly, while by these measures solid‐state fluorescence quantum yields of up to 59 % could indeed be achieved, the absorption and fluorescence spectra of the solid‐state materials in all examples still reveal substantial electronic interactions between the PBI dyes whose large π‐scaffolds appear to attract each other in sometimes rather unexpected ways with the concomitant deterioration of the fluorescence properties.…”