Using a “multifluorination” strategy, ambipolar donor–acceptor conjugated polymer with hole and electron mobility (μh and μe) up to 3.94 and 3.50 cm2 V−1 s−1, respectively, and unipolar n‐type ...donor–acceptor conjugated polymers with μe up to 4.97 cm2 V−1 s−1 is synthesized with isoindigo as acceptor units.
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 cm2 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.
n‐Type Azaacenes Containing B←N Units Min, Yang; Dou, Chuandong; Tian, Hongkun ...
Angewandte Chemie International Edition,
February 12, 2018, Volume:
57, Issue:
7
Journal Article
Peer reviewed
We disclose a novel strategy to design n‐type acenes through the introduction of boron–nitrogen coordination bonds (B←N). We synthesized two azaacenes composed of two B←N units and six/eight linearly ...annelated rings. The B←N unit significantly perturbed the electronic structures of the azaacenes: Unique LUMOs delocalized over the entire acene skeletons and decreased aromaticity of the B←N‐adjacent rings. Most importantly, these B←N‐containing azaacenes exhibited low‐lying LUMO energy levels and high electron affinities, thus leading to n‐type character. The solution‐processed organic field‐effect transistor based on one such azaacene exhibited unipolar n‐type characteristics with an electron mobility of 0.21 cm2 V−1 s−1.
BN there makes all the difference: The introduction of B←N units into azaacenes causes significant perturbations of their electronic structures and properties: Unique LUMOs delocalized over the acene skeletons (see picture) decrease aromaticity of the B←N‐adjacent rings and n‐type character. A solution‐processed organic field‐effect transistor based on one of the azaacenes exhibited unipolar n‐type characteristics and high electron mobility.
Aggregation‐structure formation of conjugated polymers is a fundamental problem in the field of organic electronics and remains poorly understood. Herein, the molar mass dependence of the aggregation ...structure of a high‐mobility conjugated copolymer (TDPP‐Se) comprising thiophene‐flanked diketopyrrolopyrrole and selenophene is thoroughly shown. Five batches of TDPP‐Se are prepared with the number‐average molecular weights (Mn) varied greatly from 21 to 135 kg mol−1. Small‐angle neutron scattering and transmission electron microscopy are combined to probe the solution structure of these polymers, consistently using a deuterated solvent. All the polymers adopt 1D rod‐like aggregation structures and the radius of the 1D rods is not sensitive to the Mn, while the length increases monotonically with Mn. By utilizing the ordered packing of the aggregated structure in solution, a highly aligned and ordered film is prepared and, thereafter, a reliable hole mobility of 13.8 cm2 V−1 s−1 is realized in organic thin‐film transistors with the moderate Mn batch via bar coating. The hole mobility is among the highest values reported for diketopyrrolopyrrole‐based polymers. This work paves the way to visualize the real aggregated structure of polymer semiconductors in solution and sheds light on the microstructure control of high‐performance electronic devices.
The molar mass dependence on aggregation structure evolution and charge transport of TDPP‐Se is thoroughly examined by neutron scattering and complementary techniques. The rod‐like preaggregate with moderate length favors a highly aligned and ordered structure by bar coating. Hence, a reliable hole mobility up to ≈14 cm2 V−1 s−1 is recorded for thin‐film transistors using diketopyrrolopyrrole‐based polymers.
High‐performance unipolar n‐type conjugated polymers (CPs) are critical for the development of organic electronics. In the current paper, four “weak donor–strong acceptor” n‐type CPs based on ...pyridine flanked diketopyrrolopyrrole (PyDPP), namely PPyDPP1‐4FBT, PPyDPP2‐4FBT, PPyDPP1‐4FTVT, and PPyDPP2‐4FTVT, are synthesized via direct arylation polycondensation by using 3,3′,4,4′‐tetrafluoro‐2,2′‐bithiophene (4FBT) or (E)‐1,2‐bis(3,4‐difluorothien‐2‐yl)ethene (4FTVT) as weak donor unit. All four polymers exhibit low‐lying highest occupied molecular orbital (≈ −5.90 eV) and lowest unoccupied molecular orbital energy levels (≈ −3.70 eV). Top‐gate/bottom‐contact organic field‐effect transistors based on all four polymers display unipolar n‐channel characteristics with electron mobility (µe) above 1 cm2 V−1 s−1 in air, and presented linear |ISD|1/2 −VGS plots and weak dependence of the extracted moblity on gate voltage (VGS), indicative of the reliability of the extracted mobility values. Importantly, the devices based on PPyDPP1‐4FBT and PPyDPP2‐4FBT show a pure unipolar n‐channel transistor behavior as revealed by the typical unipolar n‐channel output characteristics and clear off‐regimes in transfer characteristics. Attributed to its high crystallinity and favorable thin film morphology, PPyDPP2‐4FBT shows the highest µe of 2.45 cm2 V−1 s−1, which is among the highest for unipolar n‐type CPs reported to date. This is also the first report for DPP based pure n‐type CPs with µe greater than 1 cm2 V−1 s−1.
The “weak donor–strong acceptor” strategy is adopted to synthesize unipolar n‐type conjugated polymers via direct arylation polycondensation by using fluorinated thiophene moieties as the weak donors and pyridine flanked diketopyrrolopyrrole as the strong acceptor. Pure unipolar n‐channel organic field effect transistors (OFETs) with an electron mobility of 2.45 cm2 V−1 s−1 and a current on/off ratio of ≈105 in the air are fabricated.
A series of 1,3‐indandione‐terminated π‐conjugated quinoids were synthesized by alkoxide‐mediated rearrangement reaction of the respective alkene precursors, followed by air oxidation. This new ...protocol allows access to quinoidal compounds with variable termini and cores. The resulting quinoids all show LUMO levels below −4.0 eV and molar extinction coefficients above 105 L mol−1 cm−1. The optoelectronic properties of these compounds can be regulated by tuning the central cores as well as the aryl termini ascribed to the delocalized frontier molecular orbitals over the entire molecular skeleton involving aryl termini. n‐Channel organic thin‐film transistors with electron mobility of up to 0.38 cm2 V−1 s−1 were fabricated, showing the potential of this new class of quinoids as organic semiconductors.
Electronic building blocks: 1,3‐Indandione‐terminated quinoids with various termini and central cores were synthesized by an alkoxide‐mediated rearrangement reaction. Their properties can be regulated by tuning the central cores and the aryl termini. These compounds display unipolar n‐type semiconductor characteristics with electron mobilities of up to 0.38 cm2 V−1 s−1.
Three highly rigid and planar low‐bandgap conjugated polymers comprising alternate isoindigo and dithienocarbazole groups are synthesized for the fabrication of high performance polymer solar cells. ...Power conversion efficiencies of up to 7.2% for conventional devices and 8.2% for inverted devices are demonstrated.
Synthesis of triangulene and its derivatives is challenging due to their intrinsic high spin nature. Herein, we report solution‐phase synthesis and isolation of a nitrogen‐doped triangulene (i.e., ...aza‐triangulene) (NT) and its cation (NT+) in single‐crystal form. Notably, the cation NT+ can be regarded as an isoelectronic structure of the corresponding all‐carbon triangulene. Both NT and NT+ show reasonable stability due to kinetic blocking by bulky and electron‐withdrawing aryl substituents, and intramolecular donor‐acceptor interaction. Bond length analysis, magnetic measurements and theoretical calculations reveal that the neutral NT has a doublet ground state with a zwitterionic character, while the cation NT+ exhibits a triplet ground state with a singlet‐triplet energy gap of +0.84 kcal mol−1. This study provides a rational strategy to access high‐spin systems by heteroatom doping of pure π‐conjugated polycyclic hydrocarbons.
A nitrogen‐doped triangulene and its cation were synthesized and isolated in crystalline form. The cation is an isoelectronic structure of triangulene, showing a triplet ground state with a singlet‐triplet energy gap of about 0.84 kcal mol−1.
Herein, we report the synthesis and characterization of a series of 1benzothieno3,2-b1benzothiophene (BTBT)-based asymmetric conjugated molecules, that is, ...2-(5-alkylthiophen-2-yl)1benzothieno3,2-b1benzothiophene (BTBT-Tn, in which T and n represent thiophene and the number of carbons in the alkyl group, respectively). All of the molecules with n ≥ 4 show mesomorphism and display smectic A, smectic B (n = 4), or smectic E (n > 4) phases and then crystalline phases in succession upon cooling from the isotropic state. Alkyl chain length has a noticeable influence on the microstructures of vacuum-deposited films and therefore on the performance of the organic thin-film transistors (OTFTs). All molecules except for 2-(thiophen-2-yl)1benzothieno3,2-b1benzothiophene and 2-(5-ethylthiophen-2-yl)1benzothieno3,2-b1benzothiophene showed OTFT mobilities above 5 cm2 V–1 s–1. 2-(5-Hexylthiophen-2-yl)1benzothieno3,2-b1benzothiophene and 2-(5-heptylthiophen-2-yl)1benzothieno3,2-b1benzothiophene showed the greatest OTFT performance with reliable hole mobilities (μ) up to 10.5 cm2 V–1 s–1 because they formed highly ordered and homogeneous films with diminished grain boundaries.
