Jin-Hu Dou

Influence of Alkyl Chain Branching Positions on the Hole Mobilities of Polymer Thin‐Film Transistors

Four polymers that contain alkyl chains branched at different positions on the polymer backbone are prepared. A polymer with 4-decyltetradecyl chains gives an impressive mobility of 3.62 cm(2) V(-1) s(-1) . This may arise from tighter polymer packing as well as stacking conformation change of the polymer backbone induced by the branching of the alkyl chains.

Ambipolar polymer field-effect transistors based on fluorinated isoindigo: high performance and improved ambient stability.

Ambipolar transport behavior in isoindigo-based conjugated polymers is observed for the first time. Fluorination on the isoindigo unit effectively lowers the LUMO level of the polymer and significantly increases the electron mobility from 10(-2) to 0.43 cm(2) V(-1) s(-1) while maintaining high hole mobility up to 1.85 cm(2) V(-1) s(-1) for FET devices fabricated in ambient. Further investigation indicates that fluorination also affects the interchain interactions of polymer backbones, thus leading to different polymer packing in thin films.

Electron-Deficient Poly(p-phenylene vinylene) Provides Electron Mobility over 1 cm2 V-1 s-1 under Ambient Conditions

Poly(p-phenylene vinylene) derivatives (PPVs) are one of the most widely investigated p-type polymers in organic electronics. PPVs generally exhibit electron mobilities lower than 10(-4) cm(2) V(-1) s(-1), thus hindering their applications in high-performance polymer field-effect transistors and organic photovoltaics. Herein, we design and synthesize a novel electron-deficient PPV derivative, benzodifurandione-based PPV (BDPPV). This new PPV derivative displays high electron mobilities up to 1.1 cm(2) V(-1) s(-1) under ambient conditions (4 orders of magnitude higher than those of other PPVs), because it overcomes common defects in PPVs, such as conformational disorder, weak interchain interaction, and a high LUMO level. BDPPV represents the first polymer that can transport electrons over 1 cm(2) V(-1) s(-1) under ambient conditions.

A BDOPV-Based Donor-Acceptor Polymer for High-Performance n-Type and Oxygen-Doped Ambipolar Field-Effect Transistors

An electron-deficient building block BDOPV is developed to construct a new donor-acceptor conjugated polymer BDOPV-2T for high-performance n-type and oxygen-doped ambipolar polymer field-effect transistors. A high electron mobility up to 1.74 cm(2) V(-1) s(-1) is demonstrated under ambient conditions. Furthermore, the oxygen-doping effect and possible mechanism are discussed.

Chlorination as a useful method to modulate conjugated polymers: balanced and ambient-stable ambipolar high-performance field-effect transistors and inverters based on chlorinated isoindigo polymers

For the first time, ambient-stable and balanced carrier transport is achieved in polymer ambipolar field-effect transistors (FETs) and inverters with high performance. With chlorinated isoindigo polymers, FETs fabricated in ambient conditions show hole mobilities up to 0.81 cm2 V−1 s−1 and dramatically increased electron mobilities from 10−2 to 0.66 cm2 V−1 s−1. Hence, chlorination is effective to modulate electronic properties and improve the device performance of conjugated polymers.

Fine-Tuning of Crystal Packing and Charge Transport Properties of BDOPV Derivatives through Fluorine Substitution

Molecular packing in organic single crystals greatly influences their charge transport properties but can hardly be predicted and designed because of the complex intermolecular interactions. In this work, we have realized systematic fine-tuning of the single-crystal molecular packing of five benzodifurandione-based oligo(p-phenylenevinylene) (BDOPV)-based small molecules through incorporation of electronegative fluorine atoms on the BDOPV backbone. While these molecules all exhibit similar column stacking configurations in their single crystals, the intermolecular displacements and distances can be substantially modified by tuning of the amounts and/or the positions of the substituent fluorine atoms. Density functional theory calculations showed that the subtle differences in charge distribution or electrostatic potential induced by different fluorine substitutions play an important role in regulating the molecular packing of the BDOPV compounds. Consequently, the electronic couplings for electron transfer can vary from 71 meV in a slipped stack to 201 meV in a nearly cofacial antiparallel stack, leading to an increase in the electron mobility of the BDOPV derivatives from 2.6 to 12.6 cm(2) V(-1) s(-1). The electron mobility of the five molecules did not show a good correlation with the LUMO levels, indicating that the distinct difference in charge transport properties is a result of the molecular packing. Our work not only provides a series of high-electron-mobility organic semiconductors but also demonstrates that fluorination is an effective approach for fine-tuning of single-crystal packing modes beyond simply lowering the molecular energy levels.

Strong Electron‐Deficient Polymers Lead to High Electron Mobility in Air and Their Morphology‐Dependent Transport Behaviors

Planar backbone, locked conformation, and low lowest unoccupied molecular orbital level provide polymer F4 BDOPV-2T with ultrahigh electron mobilities of up to 14.9 cm(2) V(-1) s(-1) and good air stability. It is found that the nonlinear transfer curves can be tuned to near-ideal ones by changing fabrication conditions, indicating that film morphology largely contributes to the nonlinear transfer curves in high-mobility conjugated polymers.

A Cofacially Stacked Electron-Deficient Small Molecule with a High Electron Mobility of over 10 cm(2) V-1 s(-1) in Air

A strong, electron-deficient small molecule, F4 -BDOPV, has a lowest unoccupied molecular orbital (LUMO) level down to -4.44 eV and exhibits cofacial packing in single crystals. These features provide F4 -BDOPV with good ambient stability and large charge-transfer integrals for electrons, leading to a high electron mobility of up to 12.6 cm(2) V(-1) s(-1) in air.

A corannulene-based donor–acceptor polymer for organic field-effect transistors

For the first time, the corannulene unit was incorporated directly into the backbone of conjugated polymers. A new donor–acceptor (D–A) copolymer PICBT using imide-fused corannulene as acceptor was synthesized and its performance in organic field-effect transistors (OFETs) was tested. PICBT exhibited ambipolar transporting property with a hole mobility of 0.025 cm2 V−1 s−1 and electron mobility of 7.45 × 10−5 cm2 V−1 s−1 when the substrates were treated with octyltrimethoxysilane (OTS). If the substrates were not modified with OTS, PICBT showed lower device performances with a hole mobility of 4.62 × 10−3 cm2 V−1 s−1 and electron mobility of 1.54 × 10−4 cm2 V−1 s−1. The device performances are competitive among the amorphous materials. This work paved the way for incorporating the corannulene unit into conjugated materials.

Field-Effect Transistors: A Cofacially Stacked Electron-Deficient Small Molecule with a High Electron Mobility of over 10 cm2 V−1 s−1 in Air (Adv. Mater. 48/2015)

Compared with abundant p-type organic semiconductors with high mobilities, n-type semiconductors with mobilities over 1 cm(2) V(-1) s(-1) are rare. On page 8051, Y. Yi, J. Pei, and co-workers report a new small molecule, F4-BDOPV, with unprecedentedly high electron mobilities of up to 12.6 cm(2) V(-1) s(-1) . This is the first time that air-stable n-type organic semiconductors have shown mobilities surpassing 10 cm(2) V(-1) s(-1) , an important benchmark for practical applications.