Naphthodithiophenediimide (NDTI): Synthesis, Structure, and Applications

Abstract

A straightforward synthesis of α,β-unsubstituted and α-halogenated naphtho[2,3-b:6,7-b']dithiophenediimides (NDTIs) is described. Electrochemical and optical studies of N,N-dioctyl-NDTI demonstrate that the compound has a low-lying LUMO energy level (4.0 eV below the vacuum level) and a small HOMO-LUMO gap (~2.1 eV). With its interesting electronic and optical properties, in addition to its planar structure, NDTI is a promising building block for the development of novel π-functional materials. In fact, it afforded n-channel, p-channel, and ambipolar materials, depending on the molecular modification.

Naphthodithiophene-Based Semiconducting Materials for Applications in Organic Solar Cells

“…Incorporation of these novel building blocks into donor-acceptor π-conjugated systems should enable the ne-tuning of materials property and optimize the device performance. Highly electron-de cient diimide-functionalized naphthodithiophene is designed and synthesized; [64] the incorporation of this electron de cient naphthodithiophene should a ord a class of n-channel organic semiconductors as electron-acceptor layer in solar cells. During the development of high performance benzodithiophene-based organic semiconductors, aryl-substituted benzodithiophene building block plays an important role in advancing solar cell power conversion e ciency.…”

“…Furthermore, naphthodithiophene (NDT) shows greater versatility towards structure modi cations than benzodithiophene (BDT) since there are more opening sites on NDT. Naphthodithiophene can be functionalized with strong electron withdrawing units such as diimide groups [64] and the functionalization can be carried out at various positions [65][66][67][68]. In spite of these promising characteristics, in comparison to BDT-based organic semiconductors, NDT-based semiconductors received much less attentions in organic solar cells, which is likely due to the lack of practical synthetic routes to the NDT units.…”

N,N′-Bis(2-cyclohexylethyl)naphtho[2,3-b:6,7-b′]dithiophene Diimides: Effects of Substituents

“…The relatively low mobility of 1-based devices can be explained by its one-dimensional (1D) π-stacking columnar structure, which is not necessarily suitable for high-performance TFTs, and by the polymorphism in the thin-film state. The out-of-plane X-ray diffraction (XRD) patterns of vapor-deposited 1 thin films showed two series of peaks, one of which could be assigned to the bulk single-crystal phase and the other, to an unknown phase [16]. Naphtho[2,3-b:6,7-b 1 ]dithiophene-4,5,9,10-tetracarboxylic diimide (NDTI, Figure 1d) is an example of core-extended NDI derivatives.…”

“…Naphtho [2,3-b:6,7-b′]dithiophene-4,5,9,10-tetracarboxylic diimide (NDTI, Figure 1d) is an example of core-extended NDI derivatives. We have been interested in the NDTI structure for the following reasons [16,17]: (i) It has "chemical flexibility", which enables chemical modifications of both the imide nitrogen atoms and the thiophene α-positions. The modification of the imide nitrogens can be used to enhance solubility and/or supramolecular organization in the solid state of the resulting materials, and the substitution at the α-positions of fused thiophenes can be used to tune the electronic structure of the resulting systems by both inductive and resonance effects [18][19][20][21]; (ii) It possesses a planar structure, which is beneficial for carrier transport owing to the less sterically demanding fused-thiophene rings without β-substituents; (iii) It has slightly lower LUMO energy levels (ELUMOs: ~ −4.0 eV) and smaller HOMO-LUMO gaps than the corresponding NDI derivatives.…”

“…The modification of the imide nitrogens can be used to enhance solubility and/or supramolecular organization in the solid state of the resulting materials, and the substitution at the α-positions of fused thiophenes can be used to tune the electronic structure of the resulting systems by both inductive and resonance effects [18][19][20][21]; (ii) It possesses a planar structure, which is beneficial for carrier transport owing to the less sterically demanding fused-thiophene rings without β-substituents; (iii) It has slightly lower LUMO energy levels (ELUMOs: ~ −4.0 eV) and smaller HOMO-LUMO gaps than the corresponding NDI derivatives. In fact, with the NDTI core structure, a range of optoelectronic materials, e.g., n-type organic semiconductors, and ambipolar polymers and oligomers for field-effect transistors (FETs) and solar cell applications, have been developed [16][17][18][19][20][21].…”