Critical role of alkyl chain branching of organic semiconductors in enabling solution-processed N-channel organic thin-film transistors with mobility of up to 3.50 cm² V(-1) s(-1).

Substituted side chains are fundamental units in solution processable organic semiconductors in order to achieve a balance of close intermolecular stacking, high crystallinity, and good compatibility with different wet techniques. Based on four air-stable solution-processed naphthalene diimides fused with 2-(1,3-dithiol-2-ylidene)malononitrile groups (NDI-DTYM2) that bear branched alkyl chains with varied side-chain length and different branching position, we have carried out systematic studies on the relationship between film microstructure and charge transport in their organic thin-film transistors (OTFTs). In particular synchrotron measurements (grazing incidence X-ray diffraction and near-edge X-ray absorption fine structure) are combined with device optimization studies to probe the interplay between molecular structure, molecular packing, and OTFT mobility. It is found that the side-chain length has a moderate influence on thin-film microstructure but leads to only limited changes in OTFT performance. In contrast, the position of branching point results in subtle, yet critical changes in molecular packing and leads to dramatic differences in electron mobility ranging from ~0.001 to >3.0 cm(2) V(-1) s(-1). Incorporating a NDI-DTYM2 core with three-branched N-alkyl substituents of C(11,6) results in a dense in-plane molecular packing with an unit cell area of 127 Å(2), larger domain sizes of up to 1000 × 3000 nm(2), and an electron mobility of up to 3.50 cm(2) V(-1) s(-1), which is an unprecedented value for ambient stable n-channel solution-processed OTFTs reported to date. These results demonstrate that variation of the alkyl chain branching point is a powerful strategy for tuning of molecular packing to enable high charge transport mobilities.

[1]  Daoben Zhu,et al.  Diketopyrrolopyrrole-containing quinoidal small molecules for high-performance, air-stable, and solution-processable n-channel organic field-effect transistors. , 2012, Journal of the American Chemical Society.

[2]  I. Osaka,et al.  High-mobility semiconducting naphthodithiophene copolymers. , 2010, Journal of the American Chemical Society.

[3]  B. Cowie,et al.  The Current Performance of the Wide Range (90-2500 eV) Soft X-ray Beamline at the Australian Synchrotron , 2010 .

[4]  Thomas D Anthopoulos,et al.  Air‐Stable and High‐Mobility n‐Channel Organic Transistors Based on Small‐Molecule/Polymer Semiconducting Blends , 2012, Advanced materials.

[5]  S. Jenekhe,et al.  Naphthalene Diimide-Based Polymer Semiconductors: Synthesis, Structure–Property Correlations, and n-Channel and Ambipolar Field-Effect Transistors , 2012 .

[6]  Maxim Shkunov,et al.  Liquid-crystalline semiconducting polymers with high charge-carrier mobility , 2006, Nature materials.

[7]  H. Matsui,et al.  Inkjet printing of single-crystal films , 2011, Nature.

[8]  Aram Amassian,et al.  Solution‐Processed Small Molecule‐Polymer Blend Organic Thin‐Film Transistors with Hole Mobility Greater than 5 cm2/Vs , 2012, Advanced materials.

[9]  R. J. Kline,et al.  Three-dimensional packing structure and electronic properties of biaxially oriented poly(2,5-bis(3-alkylthiophene-2-yl)thieno[3,2-b]thiophene) films. , 2012, Journal of the American Chemical Society.

[10]  Lei Zhang,et al.  All‐Solution‐Processed, High‐Performance n‐Channel Organic Transistors and Circuits: Toward Low‐Cost Ambient Electronics , 2011, Advanced materials.

[11]  Benjamin C. K. Tee,et al.  Highly sensitive flexible pressure sensors with microstructured rubber dielectric layers. , 2010, Nature materials.

[12]  Andrew J. Lovinger,et al.  Soluble Regioregular Polythiophene Derivatives as Semiconducting Materials for Field-Effect Transistors , 1999 .

[13]  Tzung-Fang Guo,et al.  Chicken Albumen Dielectrics in Organic Field‐Effect Transistors , 2011, Advanced materials.

[14]  Zhenan Bao,et al.  Correlating Molecular Structure to Field-Effect Mobility: The Investigation of Side-Chain Functionality in Phenylene−Thiophene Oligomers and Their Application in Field Effect Transistors , 2007 .

[15]  A. Facchetti,et al.  A high-mobility electron-transporting polymer for printed transistors , 2009, Nature.

[16]  Xugang Guo,et al.  Conjugated polymers from naphthalene bisimide. , 2008, Organic letters.

[17]  Feng Zhang,et al.  Core-Expanded Naphthalene Diimides Fused with Sulfur Heterocycles and End-Capped with Electron-Withdrawing Groups for Air-Stable Solution-Processed n-Channel Organic Thin Film Transistors , 2011 .

[18]  Ping Liu,et al.  Low-temperature, solution-processed, high-mobility polymer semiconductors for thin-film transistors. , 2007, Journal of the American Chemical Society.

[19]  P. Dastoor,et al.  Methods in carbon K-edge NEXAFS: Experiment and analysis , 2006 .

[20]  Gui Yu,et al.  A stable solution-processed polymer semiconductor with record high-mobility for printed transistors , 2012, Scientific Reports.

[21]  Zhenan Bao,et al.  High‐Mobility Air‐Stable Solution‐Shear‐Processed n‐Channel Organic Transistors Based on Core‐Chlorinated Naphthalene Diimides , 2011 .

[22]  Masakazu Yamagishi,et al.  Patternable Solution‐Crystallized Organic Transistors with High Charge Carrier Mobility , 2011, Advanced materials.

[23]  E. W. Meijer,et al.  Two-dimensional charge transport in self-organized, high-mobility conjugated polymers , 1999, Nature.

[24]  Zhenan Bao,et al.  Siloxane-terminated solubilizing side chains: bringing conjugated polymer backbones closer and boosting hole mobilities in thin-film transistors. , 2011, Journal of the American Chemical Society.

[25]  V. R. Raju,et al.  Paper-like electronic displays: Large-area rubber-stamped plastic sheets of electronics and microencapsulated electrophoretic inks , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[26]  Alán Aspuru-Guzik,et al.  Tuning charge transport in solution-sheared organic semiconductors using lattice strain , 2011, Nature.

[27]  Daoben Zhu,et al.  Dicyanomethylene-Substituted Fused Tetrathienoquinoid for High-Performance, Ambient-Stable, Solution-Processable n-Channel Organic Thin-Film Transistors. , 2011 .

[28]  Myung‐Gil Kim,et al.  Thieno[3,4-c]pyrrole-4,6-dione-based polymer semiconductors: toward high-performance, air-stable organic thin-film transistors. , 2011, Journal of the American Chemical Society.

[29]  G. Gelinck,et al.  Flexible active-matrix displays and shift registers based on solution-processed organic transistors , 2004, Nature materials.

[30]  Daoben Zhu,et al.  Core-expanded naphthalene diimides fused with 2-(1,3-dithiol-2-ylidene)malonitrile groups for high-performance, ambient-stable, solution-processed n-channel organic thin film transistors. , 2010, Journal of the American Chemical Society.

[31]  Gui Yu,et al.  Highly π‐Extended Copolymers with Diketopyrrolopyrrole Moieties for High‐Performance Field‐Effect Transistors , 2012, Advanced materials.

[32]  T. Kowalewski,et al.  High-lamellar ordering and amorphous-like pi-network in short-chain thiazolothiazole-thiophene copolymers lead to high mobilities. , 2009, Journal of the American Chemical Society.

[33]  Henning Sirringhaus,et al.  Device Physics of Solution‐Processed Organic Field‐Effect Transistors , 2005 .

[34]  Yong‐Young Noh,et al.  Bithiophene-imide-based polymeric semiconductors for field-effect transistors: synthesis, structure-property correlations, charge carrier polarity, and device stability. , 2011, Journal of the American Chemical Society.

[35]  Jin-Hu Dou,et al.  Influence of Alkyl Chain Branching Positions on the Hole Mobilities of Polymer Thin‐Film Transistors , 2012, Advanced materials.

[36]  Stephen R. Forrest,et al.  The path to ubiquitous and low-cost organic electronic appliances on plastic , 2004, Nature.

[37]  K. Müllen,et al.  The Influence of Morphology on High‐Performance Polymer Field‐Effect Transistors , 2009 .

[38]  F. Würthner,et al.  Improved ambient operation of n-channel organic transistors of solution-sheared naphthalene diimide under bias stress. , 2012, Physical chemistry chemical physics : PCCP.

[39]  Daoben Zhu,et al.  One-pot synthesis of core-expanded naphthalene diimides: enabling N-substituent modulation for diverse n-type organic materials. , 2012, Organic letters.

[40]  Henning Sirringhaus,et al.  Microstructure of polycrystalline PBTTT films: domain mapping and structure formation. , 2012, ACS nano.

[41]  R. J. Kline,et al.  X-ray scattering study of thin films of poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene). , 2007, Journal of the American Chemical Society.

[42]  Robert Graf,et al.  Ultrahigh mobility in polymer field-effect transistors by design. , 2011, Journal of the American Chemical Society.

[43]  Shouke Yan,et al.  Solution-processed, high-performance nanoribbon transistors based on dithioperylene. , 2011, Journal of the American Chemical Society.

[44]  Ping Liu,et al.  High-performance semiconducting polythiophenes for organic thin-film transistors. , 2004, Journal of the American Chemical Society.

[45]  Takao Someya,et al.  Chemical and Physical Sensing by Organic Field‐Effect Transistors and Related Devices , 2010, Advanced materials.

[46]  Takao Someya,et al.  A large-area, flexible pressure sensor matrix with organic field-effect transistors for artificial skin applications. , 2004, Proceedings of the National Academy of Sciences of the United States of America.

[47]  S. Jenekhe,et al.  Phthalimide-based polymers for high performance organic thin-film transistors. , 2009, Journal of the American Chemical Society.

[48]  Henning Sirringhaus,et al.  High‐Performance Ambipolar Diketopyrrolopyrrole‐Thieno[3,2‐b]thiophene Copolymer Field‐Effect Transistors with Balanced Hole and Electron Mobilities , 2012, Advanced materials.

[49]  Chen Li,et al.  Charge transport in fibre-based perylene-diimide transistors: effect of the alkyl substitution and processing technique. , 2012, Nanoscale.

[50]  Ananth Dodabalapur,et al.  Organic and polymer transistors for electronics , 2006 .

[51]  Eric K. Lin,et al.  Critical Role of Side-Chain Attachment Density on the Order and Device Performance of Polythiophenes , 2007 .

[52]  Daoben Zhu,et al.  Multi‐Functional Integration of Organic Field‐Effect Transistors (OFETs): Advances and Perspectives , 2013, Advanced materials.

[53]  K. Müllen,et al.  Synthesis and Self-Organization of Core-Extended Perylene Tetracarboxdiimides with Branched Alkyl Substituents , 2006 .

[54]  Zhenan Bao,et al.  Chemical and engineering approaches to enable organic field-effect transistors for electronic skin applications. , 2012, Accounts of chemical research.

[55]  K. Müllen,et al.  Microstructure evolution and device performance in solution-processed polymeric field-effect transistors: the key role of the first monolayer. , 2012, Journal of the American Chemical Society.

[56]  S. P. Tiwari,et al.  Solution-Processed Molecular Bis(Naphthalene Diimide) Derivatives with High Electron Mobility , 2011 .

[57]  Wei Xu,et al.  Interface engineering of semiconductor/dielectric heterojunctions toward functional organic thin-film transistors. , 2011, Nano letters.

[58]  Bernard Kippelen,et al.  A high-mobility electron-transport polymer with broad absorption and its use in field-effect transistors and all-polymer solar cells. , 2007, Journal of the American Chemical Society.

[59]  Zhenan Bao,et al.  High-mobility field-effect transistors from large-area solution-grown aligned C60 single crystals. , 2012, Journal of the American Chemical Society.

[60]  A. Facchetti,et al.  Design, synthesis, and characterization of ladder-type molecules and polymers. Air-stable, solution-processable n-channel and ambipolar semiconductors for thin-film transistors via experiment and theory. , 2009, Journal of the American Chemical Society.

[61]  Michael A. Haase,et al.  Pentacene-based radio-frequency identification circuitry , 2003 .

[62]  Zhihua Chen,et al.  Naphthalenedicarboximide- vs perylenedicarboximide-based copolymers. Synthesis and semiconducting properties in bottom-gate N-channel organic transistors. , 2009, Journal of the American Chemical Society.