Diselenophene-Dithioalkylthiophene Based Quinoidal Small Molecules for Ambipolar Organic Field Effect Transistors

This work presents a series of novel quinoidal organic semiconductors based on diselenophene-dithioalkylthiophene (DSpDST) conjugated cores with various side-chain lengths (-thiohexyl, -thiodecyl, and -thiotetradecyl, designated DSpDSTQ-6, DSpDSTQ-10, and DSpDSTQ-14, respectively). The purpose of this research is to develop solution-processable organic semiconductors using dicyanomethylene end-capped organic small molecules for organic field effect transistors (OFETs) application. The physical, electrochemical, and electrical properties of these new DSpDSTQs are systematically studied, along with their performance in OFETs and thin film morphologies. Additionally, the molecular structures of DSpDSTQ are determined through density functional theory (DFT) calculations and single-crystal X-ray diffraction analysis. The results reveal the presence of intramolecular S (alkyl)···Se (selenophene) interactions, which result in a planar SR-containing DSpDSTQ core, thereby promoting extended π-orbital interactions and efficient charge transport in the OFETs. Moreover, the influence of thioalkyl side chain length on surface morphologies and microstructures is investigated. Remarkably, the compound with the shortest thioalkyl chain, DSpDSTQ-6, demonstrates ambipolar carrier transport with the highest electron and hole mobilities of 0.334 and 0.463 cm2 V-1 s-1 , respectively. These findings highlight the excellence of ambipolar characteristics of solution-processable OFETs based on DSpDSTQs even under ambient conditions.

Novel Diketopyrrolopyrrole-Based π-Conjugated Molecules Synthesized Via One-Pot Direct Arylation Reaction

Diketopyrrolopyrrole (DPP) is an important type of π-conjugated building block for high-performance organic electronic materials. DPP-based conjugated materials are usually synthesized via Suzuki, Stille, or Negishi cross-coupling reactions, which require organometallic precursors. In this paper, a series of novel phenyl-cored DPP molecules, including five meta-phenyl-cored molecules and four para-phenyl-cored molecules, have been synthesized in moderate to good yields, in a facile manner, through the Pd-catalyzed direct arylation of C–H bonds, and their optoelectrical properties have been investigated in detail. All new molecules have been fully characterized by NMR, MALDI-TOF MS, elemental analysis, UV–visible spectroscopy, and cyclic voltammetry. This synthetic strategy has evident advantages of atom- and step-economy and low cost, compared with traditional cross-coupling reactions.

Self-assembly, self-sorting, and electronic properties of a diketopyrrolopyrrole hydrogelator

We show here the first example of a hydrogel formed from a symmetrically functionalised diketopyrrolopyrrole aromatic core. Gelation is triggered by change in pH. Not only does this gelator form aggregated, entangled structures at low pH, but it also forms worm-like micelles at high pH. The structures at high pH can be aligned using shear to provide conductive materials.

Direct heteroarylation polymerization: guidelines for defect-free conjugated polymers

Direct (hetero)arylation polymerization (DHAP) has emerged as a valuable and atom-economical alternative to traditional cross-coupling methods for the synthesis of low-cost and efficient conjugated polymers for organic electronics. However, when applied to the synthesis of certain (hetero)arene-based materials, a lack of C-H bond selectivity has been observed. To prevent such undesirable side-reactions, we report the design and synthesis of new, bulky, phosphine-based ligands that significantly enhance selectivity of the DHAP process for both halogenated and non-halogenated electron-rich and electron-deficient thiophene-based comonomers. To better understand the selectivity issues, density functional theory (DFT) calculations have been performed on various halogenated and non-halogenated electron-rich and electron-deficient thiophene-based comonomers. Calculations showed that the presence of bromine atoms decreases the energy of activation (Ea) of the adjacent C-H bonds, allowing undesirable β-defects for some brominated aromatic units. Both calculations and the new ligands should lead to the rational design of monomers and methods for the preparation of defect-free conjugated polymers from DHAP.

Diketopyrrolopyrrole derivative functionalized graphene for high performance visible-light photodetectors

Although graphene has unique electronic and optical properties, its application in photodetectors is still limited due to its low optical absorption.

Control of consistent ordering in π-conjugated polymer films for organic field-effect transistor applications

A conjugated copolymer, pDPP-(TV)₂B-2DO, including donor and acceptor blocks of 1,4-bis((E)-2-(thiophen-2-yl)vinyl)benzene and diketopyrrolopyrrole derivatives, respectively, was synthesized for organic field-effect transistor applications.

Broadband photoresponse promoted by interfacial electron transfer in diketopyrrolopyrrole-based compound/ZnO hybrid nanocomposites

High photoresponse covering the UV-vis region was realized in the TTDPP/ZnO hybrid system, which is attributed to the efficient cascade electron transfer process.

Facile synthesis of arylthiophenyl-functionalized diketopyrrolopyrrole derivatives via direct C–H arylation: characterization and utilization in organic electronic devices

We report the synthesis and characterization of three arylthiophenyl-functionalized diketopyrrolopyrrole derivatives with different end-capping groups via direct C–H arylation.

High Mobility Ambipolar Diketopyrrolopyrrole-Based Conjugated Polymer Synthesized Via Direct Arylation Polycondensation

A diketopyrrolopyrrole-based conjugated polymer, PDPP-4FTVT, which exhibits ambipolar transport behavior in air with hole and electron mobilities up to 3.40 and 5.86 cm(2) V(-1) s(-1), respectively, is synthesized via direct arylation polycondensation. Incorporation of F-atoms in β-positions of thiophene rings dramatically improves the efficiency of direct arylation polycondensation.

Enabling high-mobility, ambipolar charge-transport in a DPP-benzotriazole copolymer by side-chain engineering

In this article we discuss the synthesis of four new low band-gap co-polymers based on the diketopyrrolopyrrole (DPP) and benzotriazole (BTZ) monomer unit.

In this article we discuss the synthesis of four new low band-gap co-polymers based on the diketopyrrolopyrrole (DPP) and benzotriazole (BTZ) monomer unit. We demonstrate that the BTZ unit allows for additional solubilizing side-chains on the co-monomer and show that the introduction of a linear side-chain on the DPP-unit leads to an increase in thin-film order and charge-carrier mobility if a sufficiently solubilizing, branched, side chain is attached to the BTZ. We compare two different synthetic routes, direct arylation and Suzuki-polycondensation, by a direct comparison of polymers obtained via the two routes and show that direct arylation produces polymers with lower electrical performance which we attribute to a higher density of chain Furthermore we demonstrate that a polymer utilizing this design motif and synthesized via Suzuki-polycondensation ((l-C₁₈)-DPP-(b-C₁₇)-BTZ) exhibits exceptionally high and near balanced average electron and hole mobilities >2 cm² V^–1 s^–1 which are among the highest, robustly extracted mobility values reported for DPP copolymers in a top-gate configuration to date. Our results demonstrate clearly that linear side chain substitution of the DPP unit together with co-monomers that allow for the use of sufficiently long or branched solubilizing side chains can be an attractive design motif for solution processable, high mobility DPP copolymers.

A high mobility DPP-based polymer obtained via direct (hetero)arylation polymerization

Many diketopyrrolopyrrole-based (DPP) polymers have shown remarkable transport properties and to fabricate cost efficient materials, the new direct (hetero)arylation polymerization (DHAP) could become a valuable tool.

Solution-grown single-crystalline microwires of a molecular semiconductor with improved charge transport properties

Preparation and structural analysis of highly ordered single crystalline wires of a diketopyrrolopyrrole (DPP) molecular semiconductor grown through a solution process are reported, and the static/dynamic electrical response of an organic electronic device using the DPP semiconductor has been analyzed.