Microstructure of polycrystalline PBTTT films: domain mapping and structure formation.

We utilize near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and scanning transmission X-ray microscopy (STXM) to study the microstructure and domain structure of polycrystalline films of the semiconducting polymer poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT). Total electron yield NEXAFS spectroscopy is used to examine the surface structure of the first 1-2 molecular layers, while bulk-sensitive STXM is used to produce maps of domain orientation and order sampled through the entire film thickness. We study different phases of PBTTT including as-cast, terraced and nanoribbon morphologies produced via spin-coating as well as aligned films of as-cast and nanoribbon morphologies produced by zone-casting. For the terraced morphology, domains are observed that are larger than the size of the terraced surface features, and the calculated degree of order is reduced compared to the nanoribbon morphology. For zone-cast films, we find that, although little optical anisotropy is observed in the bulk of as-cast films, a high degree of surface structural anisotropy is observed with NEXAFS spectroscopy, similar to what is observed in annealed nanoribbon films. This observation indicates that the aligned surface structure in unannealed zone-cast films templates the bulk ordering of the aligned nanoribbon phase. STXM domain mapping of aligned nanoribbon films reveals elongated, micrometer-wide domains with each domain misoriented with respect to its neighbor by up to 45°, but with broad domain boundaries. Within each nanoribbon domain, a high degree of X-ray dichroism is observed, indicating correlated ordering throughout the bulk of the film.

[1]  M. Antognazza,et al.  Sub‐Micrometer Charge Modulation Microscopy of a High Mobility Polymeric n‐Channel Field‐Effect Transistor , 2011, Advanced materials.

[2]  C. McNeill.  Imaging the domain structure of organic semiconductor films , 2011 .

[3]  C. McNeill,et al.  Mapping of Domain Orientation and Molecular Order in Polycrystalline Semiconducting Polymer Films with Soft X‐Ray Microscopy , 2011 .

[4]  H. Sirringhaus,et al.  Anisotropy of Charge Transport in a Uniaxially Aligned and Chain‐Extended, High‐Mobility, Conjugated Polymer Semiconductor , 2011 .

[5]  T. Elsaesser,et al.  High‐Resolution Near‐Field Optical Investigation of Crystalline Domains in Oligomeric PQT‐12 Thin Films , 2011 .

[6]  R. J. Kline,et al.  Molecular Characterization of Organic Electronic Films , 2011, Advanced materials.

[7]  R. J. Kline,et al.  Structural Origin of Gap States in Semicrystalline Polymers and the Implications for Charge Transport , 2010, 1012.2240.

[8]  S. D. Hudson,et al.  In‐Plane Liquid Crystalline Texture of High‐Performance Thienothiophene Copolymer Thin Films , 2010 .

[9]  Paul Heremans,et al.  Organic Transistors in Optical Displays and Microelectronic Applications , 2010, Advanced materials.

[10]  H. Sirringhaus,et al.  Charge Transport Physics of Conjugated Polymer Field‐Effect Transistors , 2010, Advanced materials.

[11]  Alberto Salleo,et al.  Microstructural Characterization and Charge Transport in Thin Films of Conjugated Polymers , 2010, Advanced materials.

[12]  M. Brinkmann,et al.  Highly Oriented and Nanotextured Films of Regioregular Poly(3-hexylthiophene) Grown by Epitaxy on the Nanostructured Surface of an Aromatic Substrate , 2010 .

[13]  S. Leone,et al.  Crystal Grain Orientation in Organic Homo- and Heteroepitaxy of Pentacene and Perfluoropentacene Studied with X-ray Spectromicroscopy , 2010 .

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

[15]  M. Halik,et al.  In situ STXM investigations of pentacene-based OFETs during operation , 2010 .

[16]  T. Tyliszczak,et al.  X-ray Microscopy Imaging of the Grain Orientation in a Pentacene Field-Effect Transistor , 2010 .

[17]  A. Salleo,et al.  Microstructural Origin of High Mobility in High‐Performance Poly(thieno‐thiophene) Thin‐Film Transistors , 2010, Advanced materials.

[18]  Henning Sirringhaus,et al.  Local charge trapping in conjugated polymers resolved by scanning Kelvin probe microscopy. , 2009, Physical review letters.

[19]  Alberto Salleo,et al.  Large modulation of carrier transport by grain-boundary molecular packing and microstructure in organic thin films. , 2009, Nature materials.

[20]  M. Toney,et al.  Charge‐Transport Anisotropy Due to Grain Boundaries in Directionally Crystallized Thin Films of Regioregular Poly(3‐hexylthiophene) , 2009 .

[21]  David S. Germack,et al.  Controlling the orientation of terraced nanoscale "ribbons" of a poly(thiophene) semiconductor. , 2009, ACS nano.

[22]  R. J. Kline,et al.  Semiconducting Thienothiophene Copolymers: Design, Synthesis, Morphology, and Performance in Thin‐Film Organic Transistors , 2009 .

[23]  Maxim Shkunov,et al.  Solid‐State Supramolecular Organization of Polythiophene Chains Containing Thienothiophene Units , 2009 .

[24]  H. Sirringhaus,et al.  A scanning Kelvin probe study of charge trapping in zone-cast pentacene thin film transistors , 2009, Nanotechnology.

[25]  T. Tyliszczak,et al.  PolLux: a new facility for soft x-ray spectromicroscopy at the Swiss Light Source. , 2008, The Review of scientific instruments.

[26]  E. Tadmor,et al.  Grain Orientation Mapping of Polycrystalline Organic Semiconductor Films by Transverse Shear Microscopy , 2008 .

[27]  N. Koch,et al.  Grain‐Boundary Evolution in a Pentacene Monolayer , 2008 .

[28]  Andrew J. Moad,et al.  Molecular Basis of Mesophase Ordering in a Thiophene-Based Copolymer , 2008 .

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

[30]  C. McNeill,et al.  X-Ray Microscopy of Photovoltaic Polyfluorene Blends: Relating Nanomorphology to Device Performance , 2007 .

[31]  R. J. Kline,et al.  High Carrier Mobility Polythiophene Thin Films: Structure Determination by Experiment and Theory† , 2007 .

[32]  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.

[33]  Eric K. Lin,et al.  Significant dependence of morphology and charge carrier mobility on substrate surface chemistry in high performance polythiophene semiconductor films , 2007 .

[34]  H. Ade,et al.  The PolLux Microspectroscopy Beam line at the Swiss Light Source , 2007 .

[35]  C. McNeill,et al.  X-ray spectromicroscopy of polymer/fullerene composites: quantitative chemical mapping. , 2006, Small.

[36]  A. Wee,et al.  Large damage threshold and small electron escape depth in X-ray absorption spectroscopy of a conjugated polymer thin film. , 2006, Langmuir : the ACS journal of surfaces and colloids.

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

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

[39]  Krzysztof Matyjaszewski,et al.  Long-range ordered thin films of block copolymers prepared by zone-casting and their thermal conversion into ordered nanostructured carbon. , 2005, Journal of the American Chemical Society.

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

[41]  Gilles Horowitz,et al.  Organic Field‐Effect Transistors , 1998 .