ELECTRODEPOSITION OF NOVEL POLY(NAPHTHALENEDIIMIDE-QUATERTHIOPHENE) THIN FILMS AND APPLICATIONS IN PLASTIC OPTOELECTRONICS DEVICES

A novel symmetric naphthalenediimide-quaterthiophene derivative (NDIT4d) has been polymerized on different substrates including glassy carbon and ITO/PET electrodes by means of electrochemical methods. XPS and UV-VIS spectroscopy as well as cyclic voltammetry have been employed for characterizing the thin film chemical features, the band gap and the HOMO and LUMO levels. DFT computational studies were in close agreement with the experimental observables also showing intriguing geometrical effects on the band gap energy values. The comparison of the energy levels locations of the electrodeposited poly(naphthalenediimide-quaterthiophene) derivative (e-PNDIT4) and P3HT thin films transferred b…

Enhanced Thin-Film Transistor Performance by Combining 13,6-N-Sulfinylacetamidopentacene with Printed PEDOT:PSS Electrodes

Bottom-contact/bottom-gate organic thin-film transistors (OTFTs) are fabricated using a soluble pentacene precursor (13,6-N-sulfinylacetamidopentacene; SAP) and inkjet printed PEDOT:PSS electrodes on bare SiO2 dielectrics. Saturation mobility, Ion/Ioff ratio, and threshold voltage parameters, respectively, of 0.27 cm2 V−1 s−1, 105, and −4.25 V were measured under ambient conditions after the thermal conversion of SAP to pentacene in 100 μm long channel OTFT devices. The results obtained by the above solution approach are comparable to that of vapor-phase grown pentacene-based OTFTs with photolithographic gold contacts and organic buffer layers and/or inorganic injection layers. The present …

Symmetric naphthalenediimidequaterthiophenes for electropolymerized electrochromic thin films

A new symmetric naphthalenediimidequaterthiophene (s-NDI2ODT4) was synthesized and exhibited the capability to electropolymerize alone or with EDOT affording polymers with controlled donor/acceptor monomer ratios. s-NDI2ODT4-EDOT-based copolymers showed low band gaps, wide optical absorption ranges extending to the near IR region, tuned electrical properties, thin-film surface morphology and hydrophilicity as well as high coloration efficiency in electrochromic devices.

Role of photoactive layer morphology in high fill factor all-polymer bulk heterojunction solar cells

We report on the realization of all-polymer solar cells based on blends of poly(3-hexylthiophene-2,5-diyl) (P3HT) as a donor and poly{[N,N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} (P(NDI2OD-T2)) as an acceptor. High fill factors are demonstrated for the first time in this class of devices suggesting high dissociation efficiency for the bounded electron-hole pairs and balanced electron and hole mobility along the thin films. The use of the high-mobility n-type P(NDI2OD-T2) polymer enables us to overcome one of the problems limiting the efficiency of all-polymer solar cells, resulting in fill factors comparable with those reported for …

Organic Transistors: Supramolecular Order of Solution-Processed Perylenediimide Thin Films: High-Performance Small-Channel n-Type Organic Transistors (Adv. Funct. Mater. 23/2011)

Carbonyl-functionalized quaterthiophenes: a study of the vibrational Raman and electronic absorption/emission properties guided by theoretical calculations.

This work investigates the evolution of the molecular, vibrational, and optical properties within a family of carbonyl-functionalized quaterthiophenes: 5,5'''-diheptanoyl-2,2':5',2'':5'',2'''-quaterthiophene (1), 5,5'''-diperfluorohexylcarbonyl-2,2':5',2'':5'',2'''-quaterthiophene (2), and 2,7-[bis(5-perfluorohexylcarbonylthien-2-yl)]-4H-cyclopenta[2,1-b:3,4-b']-dithiophene-4-one (3). The analysis is performed by Raman and UV/Vis absorption/excitation/fluorescence spectroscopy in combination with density functional calculations. Theoretical calculations show that substitution with carbonyl groups and perfluorohexyl chains induces progressive quinoidization of the π-conjugated backbone in co…

Supramolecular Order of Solution-Processed Perylenediimide Thin Films

N,N ′ -1 H ,1 H -perfl uorobutyl dicyanoperylenecarboxydiimide (PDIF-CN 2 ), a soluble and air stable n-type molecule, undergoes signifi cant reorganization upon thermal annealing after solution deposition on several substrates with different surface energies. Interestingly, this system exhibits an exceptional edge-on orientation regardless of the substrate chemistry. This preferential orientation is rationalized in terms of strong intermolecular interactions between the PDIF-CN 2 molecules. The presence of a pronounced π– π stacking is confi rmed by combining near-edge X-ray absorption fi ne structure spectroscopy (NEXAFS), dynamic scanning force microscopy (SFM) and surface energy measure…

From monolayer to multilayer N-channel polymeric field-effect transistors with precise conformational order

Monolayer field-effect transistors based on a high-mobility n-type polymer are demonstrated. The accurate control of the long-range order by Langmuir-Schafer (LS) deposition yields dense polymer packing exhibiting good injection properties, relevant current on/off ratio and carrier mobility in a staggered configuration. Layer-by-layer LS film transistors of increasing thickness are fabricated and their performance compared to those of spin-coated films.

Naphthalenediimide Polymers with Finely Tuned In-Chain π-Conjugation: Electronic Structure, Film Microstructure, and Charge Transport Properties

Naphthalenediimide-based random copolymers (PNDI-TVTx) with different π-conjugated dithienylvinylene (TVT) versus π-nonconjugated dithienylethane (TET) unit ratios (x = 100→0%) are investigated. The PNDI-TVTx-transistor electron/hole mobilities are affected differently, a result rationalized by molecular orbital topologies and energies, with hole mobility vanishing but electron mobility decreasing only by ≈2.5 times when going from x = 100% to 40%.

Regio(ir)regular naphthalenediimide- and perylenediimide-bithiophene copolymers: How MO localization controls the bandgap

Absorption spectra of regio(ir)regular naphthalenediimide (NDI)- and perylenediimide (PDI)-bithiophene (2T) donor/acceptor (D/A) copolymers are surprisingly similar despite cross-conjugation in the regioirregular structures. This result is traced back to largely localized frontier molecular orbitals (FMOs) as revealed by (time-dependent) DFT calculations. Interestingly, while the FMOs of the P(PDI-2T) copolymer are localized solely in the PDI units, they are predominantly localized in the respective D/A units of the P(NDI-2T) copolymer. The pronounced CT character of the lowest singlet state in P(NDI-2T) should give rise to a close lying CT triplet state, generating small singlet–triplet ga…