Single-Component Organic Light-Harvesting Red Luminescent Crystal

Abstract

Highly efficient photoinduced energy transfer is observed in an orthogonal bichromophore naphthalenimideperylenimide (NP), leading to strong solid-state luminescence (Φ = 0.5 ± 0.04) in the red region (λ em = 631 nm). Steric hindrance imparted by orthogonal naphthalenimide and diisopropyl phenyl units prevents the association of perylenimide moieties, thereby retaining a high quantum yield of fluorescence emission even in the crystalline state. Upon photoexcitation at 340 nm, the intramolecular parallel orientation of the transition dipoles permits efficient Coulombic coupling between naphthalenimide and perylenimide in combination with weak H-type excitonic interactions between the intermolecular perylenimide units that results in intense red fluorescence in the crystalline state of dyad NP. Negligible photoinduced electron transfer from the singlet excited state of the perylenimide to the naphthalenimide unit (ΔG = 0.44 eV) and a marginal feasibility (ca. 10%) of photoinduced electron transfer from the singlet excited state of the naphthalenimide to the peryleninimide unit (ΔG = −0.17 eV) makes the dyad strongly fluorescent when excited at both 340 and 475 nm, corresponding to the naphthalenimide and perylenimide units, respectively. A narrow emission at 631 nm, wide absorption window (300−600 nm), and high fluorescence quantum yield in the crystalline state make the dyad NP a potential candidate for optoelectronic and photonic applications.

Excited‐State Deactivation of Branched Phthalocyanine Compounds

“…This face‐to‐face stacked structure involves intramolecular aggregation; this occurs between the two Pc branches linked by the triazine group in the bis‐Pc chromophore. According to Kasha's H‐type exciton theory, the coupling of two monomers bound in a face‐to‐face geometry leads to the first excited state splitting into two exciton states, the higher of which has all of the oscillator strength, whereas the lower one is a forbidden transition . As a consequence, the absorption spectrum will blueshift .…”

“…According to Kasha's H-typee xciton theory,t he coupling of two monomers bound in af ace-to-face geometry leads to the first excited state splitting into two excitons tates, the highero fw hich has all of the oscillator strength,w hereas the lower one is af orbiddent ransition. [43][44][45] As ac onsequence, the absorption spectrum will blueshift. [43] In our results, the spectrumd oes not show an apparent blueshift, but shows as ignificant change of the intensity ratio between the vibrational bands, which is in accordance with an extension of the excitontheory.Insome studies achange of the relative intensity have been reported, similar to that occurring in the PDI chromophore dimers.…”

Structure‐Packing‐Property Correlation of Self‐Sorted Versus Interdigitated Assembly in TTF⋅TCNQ‐Based Charge‐Transport Materials

“…The Cambridge Structural Database (CSD) provides an excellent platform for a comprehensive study of a series of F⋅Q derivatives crystallized over around half a century. Our continued interests in devising de novo strategies to modulate crystal structure to enhance the functional properties of materials led to a comprehensive database study on F⋅Q‐based co‐crystals. In the current study, crystal structures of F⋅Q derivatives identified from CSD were critically analyzed with the aim of introducing a general classification of multicomponent D‐A crystals based on their packing modes.…”

“…Ac ombined study based on as eries of F·Q-based co-crystals to address the subtle intermoleculari nteractions that dictate the crystalline packinga nd its corresponding structure-packing-property relationship remains elusive. The Cambridge StructuralD atabase (CSD) [44] provides an excellent platform for ac omprehensive study of as eries of F·Q derivatives crystallized over aroundh alf ac entury.O ur continued interests in devising de novo strategies to modulate crystal structure to enhance the functional properties of materials [45][46][47][48][49][50][51] led to ac omprehensive database study on F·Q-based co-crystals. In the current study,c rystal structures of F·Q derivatives identified from CSD were critically analyzed with the aim of introducing ag eneral classification of multicomponent D-A crystalsb ased on their packing modes.…”

Excitation Energy Transfer in meta‐Substituted Phenylacetylene Multibranched Chromophores

“…[3b, 4] Optical excitation ande nergy transfer have been an important subjecta nd providedaconceptual basis for designing ands ynthesizingn ovel artificial light-harvesting and -emittingm aterials. [5] Am ajor issue in branched molecules concerns the influence of branching central core specieso ni ntramolecular interactions and energytransfer dynamics, although an umber of experimental and theoretical investigations have been carriedo ut on branched molecules with different chemical structures. [5e, 6] As an example, for branched molecules with an itrogen core, [6a,b] energy transfer among the branches may be partially coherenta tt he limit of strong electronic interactions with very fast energy transfer betweenb ranches on a3 0f ss cale and subsequent localization on one branch,w hereas, at the other extreme, a" hopping" mechanism can also be involved in the energytransfer process in the case of weak electronic interactions.…”