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The effects of the molecular structure of thiazole‐based polymers on the active layer morphologies and performances of electronic and photovoltaic devices were studied. Thus, thiazole‐based conjugated polymers with a novel thiazole‐vinylene‐thiazole (TzVTz) structure were designed and synthesized. The TzVTz structure was introduced to extend the π conjugation and coplanarity of the polymer chains. By combining alkylthienyl‐substituted benzo[1,2‐b:4,5‐b′]dithiophene (BDT) or dithieno[2,3‐d:2′,3′‐d′]benzo[1,2‐b:4,5‐b′]dithiophene (DTBDT) electron‐donating units and a TzVTz electron‐accepting unit, enhanced intermolecular interactions and charge transport were obtained in the novel polymers BDT‐TzVTz and DTBDT‐TzVTz. With a view to using the polymers in transistor and photovoltaic applications, the molecular self‐assembly in and their nanoscale morphologies of the active layers were controlled by thermal annealing to enhance the molecular packing and by introducing a diphenyl ether solvent additive to improve the miscibility between polymer donors and [6,6]phenyl‐C71‐butyric acid methyl ester (PC71BM) acceptors, respectively. The morphological characterization of the photoactive layers showed that a higher degree of π‐electron delocalization and more favorable molecular packing in DTBDT‐TzVTz compared with in BDT‐TzVTz leads to distinctly higher performances in transistor and photovoltaic devices. The superior performance of a photovoltaic device incorporating DTBDT‐TzVTz was achieved through the superior miscibility of DTBDT‐TzVTz with PC71BM and the improved crystallinity of DTBDT‐TzVTz in the nanofibrillar structure. Superior performances! The effects of the molecular structure of thiazole‐based polymers on the active layer morphologies and performances of electronic and photovoltaic devices has been studied. The higher degree of π‐electron delocalization and more favorable morphology of the DTBDT‐TzVTz polymer compared with in BDT‐TzVTz leads to distinctly higher performances in transistor and photovoltaic devices. [ABSTRACT FROM AUTHOR]

The copolymers P24DPP-silole and P29DPP-silole, each composed of diketopyrrolopyrrole (DPP) and silole derivatives, were synthesized using a Stille coupling reaction, and their electrical performances in organic field-effect transistors (OFETs) and circuits were investigated. While both the as-spun OFETs exhibited quite low field-effect hole mobility values, the OFETs subjected to thermal annealing at 150 °C exhibited typical ambipolar transport characteristics with average hole and electron mobility values of 1 × 10 −1 cm 2 /(V s) and 2 × 10 −3 cm 2 /(V s). Because the compact model was necessary to perform circuit design with the synthesized OFETs, a strategy for extracting compact model parameters was proposed for high-voltage logic circuit applications by using the industry standard compact Berkeley short-channel IGFET model (BSIM). [ABSTRACT FROM AUTHOR]

Two donor–acceptor conjugated copolymers comprised of a novel dithienophosphole (DTP) as the acceptor unit and bithiophene (BT) or decylthiophenebenzodithiophene (DTBDT) as the donor unit were synthesized and characterized to elucidate the relationship between donor–acceptor (D–A) architecture and organic field-effect transistors (OFETs) performance. These characteristics of D–A copolymers were affected by the structural suitability of donor and acceptor units. Poly(DTP-BT) had an ordered structure that facilitated charge carrier transfer. The crystallinity of poly(DTP-BT) increased as annealing temperature ( T ann ) increased. In contrast, poly(DTP-DTBDT) was amorphous regardless of T ann due to the long alkyl chains of the DTBDT units. OFET devices made with poly(DTP-BT) and annealed at 200 °C exhibit a highly crystalline morphology and a relatively high field-effect mobility (4.9 × 10 −3 cm 2 /(V·s)). [ABSTRACT FROM AUTHOR]

We investigated the effects of the solvent boiling point on organic field-effect transistor (OFET) device performances in devices prepared using two newly synthesized anthradithiophene derivatives: 9,10-di(4′-pentylphenylethynyl)-anthra[2,3-b:6,7-b′]dithiophene (DPPEADT) and 9,10-bi([9′,9′-dimethyl-fluoren-2-ylethynyl])-anthra[2,3-b:6,7-b′]dithiophene (DFEADT). DPPEADT exhibited a distinct crystalline morphology whereas DFEADT was amorphous. We characterized the relationship between the molecular structures, film morphologies, and OFET device performances in devices prepared using solvents having one of three different boiling points (chlorobenzene, 1,2-dichlorobenzene, and 1,2,4-trichlorobenzene). 1,2,4-Trichlorobenzene, which provided the highest boiling point among the solvents tested and acted as a good solvent for DPPEADT, significantly improved the field-effect mobilities of DPPEADT devices up to 0.16 cm 2 /V by enhancing the crystallinity of the film. OFETs based on amorphous DFEADT films prepared using the three solvents did not provide enhanced electrical performances. The differences between the transistor performances were attributed to the degree of π-overlap, the molecular structures, and the morphological properties of the films. [ABSTRACT FROM AUTHOR]

An organic-field effect transistor (OFET) based on a newly synthesized organic molecule with an ester end group (ANOAT) was tested in a sensor for the detection of ethanol vapor. The linearly fused acene in ANOAT forms channel layers in the OFET and the ester end group of ANOAT interacts with ethanol vapor. The ethanol sensing ability of the ANOAT-based OFET derives not from changes in the crystalline structure of the organic semiconductor but from the interaction between ethanol vapor and the ester end group, which we demonstrated by using FT-IR analysis, computational modeling, X-ray scattering, and AFM analysis. [ABSTRACT FROM AUTHOR]

Highlights: [•] New copolymers based dialkylterthiophene. [•] Among copolymers, PBTOT had relatively good solubility and crystalline structure. [•] PBTOT showed field effect mobility of 1.73×10−2 cm2 V−1 S−1. [•] PBTOT showed power conversion efficiency of 3.2%. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis and characterization of cyclohexylethenyl end-capped quaterthiophenes is reported. Additionally, an investigation of the performance of organic field-effect transistors based on these quaterthiophenes in view of the relationship between the solid-state (or aggregate) order and the electronic performance is described. UV–vis absorption measurements revealed that the quaterthiophene with an asymmetrically substituted cyclohexylethynyl end-group induced the formation of H-type aggregates, whereas the quaterthiophene with a symmetrically substituted cyclohexylethynyl end-groups favored the formation of J-type aggregates. Two-dimensional grazing-incidence wide-angle X-ray scattering studies were performed to support the molecular structure-dependent packing of films of the new quaterthiophenes. Solution-processed quaterthiophenes were tested as the active layers of p-type organic field-effect transistors with a bottom gate/top contact geometry. The field-effect mobility of devices that incorporated asymmetric quaterthiophene molecules was quite high, exceeding 0.02 cm2/V s, due to H-aggregation and good in-plane ordering. In contrast, the field-effect mobility of devices that incorporated symmetrical quaterthiophenes, was low, above 5 × 10−4 cm2/(V s), due to the formation of J-aggregates and poor in-plane ordering. A comparison of the symmetrical and asymmetrical quaterthiophene derivatives revealed that the molecular aggregation-dependent packing, determined by the cyclohexylethynyl end groups, was responsible for influencing the organic field-effect transistor performance. [Copyright &y& Elsevier]

Abstract: We demonstrate the use of n-type N,N′-ditridecyl-3,4,9,10-perylenetetracarboxylic diimide (PTCDI-C13) bottom contact organic field-effect transistors that employ photopatternable highly conductive poly(3,4-ethylenedioxythiophene):tosylate (PEDOT:Tos) source/drain electrodes characterized by a very low work function (4.3eV). Due to the low work function of this material, the electron injection barrier between PTCDI-C13 and PEDOT:Tos was 0.25eV lower than that between PTCDI-C13 and gold. The low injection barrier reduced the contact resistance, yielding a high field effect mobility in transistors based on PEDOT:Tos (0.145cm2/Vs); the field effect mobility was 16 times higher than that in transistors based on gold (0.009cm2/Vs). [Copyright &y& Elsevier]