Effect of N-Substituents on Redox, Optical, and Electronic Properties of Naphthalene Bisimides Used for Field-Effect Transistors Fabrication

Abstract

Three groups of naphthalene bisimides were synthesized and comparatively studied, namely, alkyl bisimides, alkylaryl ones, and novel bisimides containing the alkylthienyl moiety in the N-substituent. The experimental absorption spectra measured in CHCl(3) exhibit one intensive absorption band that is uniformly detected in the spectral range of 340 to 400 nm for all studied molecules. This band consists of three or four vibronic peaks. The introduction of an alkylthienyl group results in the appearance of an additional band (in the spectral range from 282 to 326 nm, depending on the position of the substituent) that can be ascribed to the pi-pi* transition in the thienyl chromophore. The minimal substituent effect on the lowest electronic transitions was explained using the quantum chemical calculations based on the time-dependent density functional theory. The investigation of the shapes of frontier orbitals have also shown that the oxidation of bisimides containing thiophene moiety is primary connected with the electron abstraction from the thienyl ring. To the contrary, the addition of an electron in the reduction process leads to an increase in the electron density in the central bisimide core. As shown by the electrochemical measurements, the onset of the first reduction potential (so-called "electrochemically determined LUMO level") is sensitive toward the type of the substituent being shifted from about -3.72 eV for bisimides with alkyl substituents to about -3.83 eV for alkylaryl ones and to about -3.94 eV for bisimides with thienyl groups. The presence of the thienyl ring also lowers the energy difference between the HOMO and LUMO orbitals. These experimental data can be well correlated with the DFT calculations in terms of HOMO/LUMO shapes and energies. Taking into account the low position of their LUMO level and their highly ordered supramolecular organization, the new bisimides are good candidates for the use in n-channel field effect transistors, operating in air. The fabricated "all organic" transistors show effective charge carrier mobilities in the range 10(-2) to 10(-4) cm(2) V(-1) s(-1) and the ON/OFF ratios exceed 10(5) for the majority of cases.

New Electron Transport Materials for High Performance Organic Solar Cells: Synthesis and Properties of Symmetrical and Asymmetrical 1,4,5,8‐Naphthalenetetracarboxylic Dianhydride Derivatives

“…A short inspection of the results indicates that HOMO and LUMO values fall quite low in the energy scale indicative of the facilitated electron injection process in the compounds under consideration. [ 26 ] LUMO energies of ND1−ND3 are close and comparable, while the LUMO of ND4 is positioned much lower (−3.78 eV) due to the presence of 1,3,4-thiadiazolyl moiety, which is characterized by higher accepting strength than pyridinyl fragments. Apparently, asymmetrical compounds exhibit similar LUMO energies with slightly lower ones found for ND6 , ND8 , and ND10 , bearing pyrimidinyl unit in the condensed part.…”

Physical, optical and gas transport properties of new processable polyimides and poly(amideimide)s obtained from 4,4′-[oxybis(4,1-phenylenethio)]dianiline and aromatic dianhydrides

“…The growth of modern technology has posed a constantly increasing need for materials that can perform well under harsh conditions, such as elevated temperatures, 4 and processable PIs with special properties have become a subject of great interest all over the world. 5,6 It was found that compounds containing imine rings have prospective applications in organic (opto)electronics and related fields, and that they are exemplary as materials for fabricating field-effect transistors, [6][7][8] organic light-emitting diodes, 9-12 solar cells [12][13][14] and photonic devices. [15][16][17] With regard to the PI microstructure, much effort is being devoted to the design and synthesis of PIs with thioether linkages.…”

Low and High Molecular Mass Dithienopyrrole–Naphthalene Bisimide Donor–Acceptor Compounds: Synthesis, Electrochemical and Spectroelectrochemical Behaviour

“…[23] In the case of NBI-(DTP) 2 the value of E red1-E red2 is by 0.05 to 0.08 Vl ower than in naphthaleneb isimides that are not core-functionalized. [19,22] This may suggest that the radical anion charged ensity is partially delocalized from the core to dithienopyrrole substituents, as corroboratedb yt he DFT calculations of unpaired spin density distribution (vide infra). The electrochemical data, concerning the negative potentialr ange, are collected in Table 1.…”

“…UV/Vis spectra of naphthalene bisimides with no substituents in the core are characterized by as trong absorption band of av ibronic character,a scribed to the arylene p-p*t ransition, with the 0-0 vibronic peak, in the vicinity of 380 nm, showing the highesti ntensity. [19] Core functionalization of these compounds with electron-donatings ubstituents gives rise to an ew band at significantly longerw avelengths, usually of charge-transfer (CT) character. [6b, 20] This CT band, with am aximum at 689 nm, is also clearly seen in the spectrum of NBI-(DTP) 2 (Figure 1a).…”