@article{mukherjee_gann_nahid_mcafee_herzing_delongchamp_ade_2021, title={Orientational Ordering within Semiconducting Polymer Fibrils}, volume={31}, ISSN={["1616-3028"]}, DOI={10.1002/adfm.202102522}, abstractNote={Abstract}, number={28}, journal={ADVANCED FUNCTIONAL MATERIALS}, author={Mukherjee, Subhrangsu and Gann, Eliot and Nahid, Masrur Morshed and McAfee, Terry and Herzing, Andrew A. and DeLongchamp, Dean M. and Ade, Harald}, year={2021}, month={Jul} }
 @article{carpenter_ghasemi_gann_angunawela_stuard_rech_ritchie_brendan t. o'connor_atkin_you_et al._2019, title={Competition between Exceptionally Long-Range Alkyl Sidechain Ordering and Backbone Ordering in Semiconducting Polymers and Its Impact on Electronic and Optoelectronic Properties}, volume={29}, ISSN={["1616-3028"]}, DOI={10.1002/adfm.201806977}, abstractNote={Abstract}, number={5}, journal={ADVANCED FUNCTIONAL MATERIALS}, author={Carpenter, Joshua H. and Ghasemi, Masoud and Gann, Eliot and Angunawela, Indunil and Stuard, Samuel J. and Rech, Jeromy James and Ritchie, Earl and Brendan T. O'Connor and Atkin, Joanna and You, Wei and et al.}, year={2019}, month={Feb} }
 @article{gann_collins_tang_tumbleston_mukherjee_ade_2016, title={Origins of polarization-dependent anisotropic X-ray scattering from organic thin films}, volume={23}, ISSN={["1600-5775"]}, DOI={10.1107/s1600577515019074}, abstractNote={Organic thin films that have no overall in-plane directional ordering often nonetheless produce anisotropic scattering patterns that rotate with the polarization of incident resonant X-rays. Isotropic symmetry is broken by local correlations between molecular orientation and domain structure. Such examples of molecular alignment at domain interfaces and within the bulk of domains, which are both critical to fields such as organic electronics, are simulated and compared with experimental scattering. Anisotropic scattering patterns are found to allow unambiguous identification of the mechanism of local molecular orientation correlations and, as such, promise to be both distinct and complementary to isotropic scattering intensity as a general measure of thin film microstructure.}, journal={JOURNAL OF SYNCHROTRON RADIATION}, author={Gann, Eliot and Collins, Brian A. and Tang, Maolong and Tumbleston, John R. and Mukherjee, Subrangsu and Ade, Harald}, year={2016}, month={Jan}, pages={219–227} }
 @article{tumbleston_collins_yang_stuart_gann_ma_you_ade_2014, title={The influence of molecular orientation on organic bulk heterojunction solar cells}, volume={8}, ISSN={["1749-4893"]}, DOI={10.1038/nphoton.2014.55}, number={5}, journal={NATURE PHOTONICS}, author={Tumbleston, John R. and Collins, Brian A. and Yang, Liqiang and Stuart, Andrew C. and Gann, Eliot and Ma, Wei and You, Wei and Ade, Harald}, year={2014}, month={May}, pages={385–391} }
 @article{gann_watson_tumbleston_cochran_yan_wang_seok_chabinyc_ade_2014, title={Topographic measurement of buried thin-film interfaces using a grazing resonant soft x-ray scattering technique}, volume={90}, ISSN={["1550-235X"]}, DOI={10.1103/physrevb.90.245421}, abstractNote={The internal structures of thin films, particularly interfaces between different materials, are critical to system properties and performance across many disciplines, but characterization of buried interface topography is often unfeasible. In this work, we demonstrate that grazing resonant soft x-ray scattering (GRSoXS), a technique measuring diffusely scattered soft x rays from grazing incidence, can reveal the statistical topography of buried thin-film interfaces. By controlling and predicting the x-ray electric field intensity throughout the depth of the film and simultaneously the scattering contrast between materials, we are able to unambiguously identify the microstructure at different interfaces of a model polymer bilayer system. We additionally demonstrate the use of GRSoXS to selectively measure the topography of the surface and buried polymer-polymer interface in an organic thin-film transistor, revealing different microstructure and markedly differing evolution upon annealing. In such systems, where only indirect control of interface topography is possible, accurate measurement of the structure of interfaces for feedback is critically important. While we demonstrate the method here using organic materials, we also show that the technique is readily extendable to any thin-film system with elemental or chemical contrasts exploitable at absorption edges.}, number={24}, journal={PHYSICAL REVIEW B}, author={Gann, Eliot and Watson, Anne and Tumbleston, John R. and Cochran, Justin and Yan, Hongping and Wang, Cheng and Seok, Jaewook and Chabinyc, Michael and Ade, Harald}, year={2014}, month={Dec} }
 @article{mcafee_gann_guan_stuart_rowe_dougherty_ade_2014, title={Toward Single-Crystal Hybrid-Carbon Electronics: Impact of Graphene Substrate Defect Density on Copper Phthalocyanine Film Growth}, volume={14}, ISSN={["1528-7505"]}, DOI={10.1021/cg500504u}, abstractNote={Graphene has long been recognized as a potential replacement for indium tin oxide as a transparent conducting substrate that may not only be cheaper to manufacture but also may provide mechanical flexibility and templating for preferential organic film growth. Here, we report the discovery that the thin film growth mode and crystal structure of copper phthalocyanine (CuPc), a prototype organic semiconductor, is extremely sensitive to even atomic-scale defects (e.g., steps) on the graphene surface and that high quality films can be grown with a well-defined crystal orientation that should be favorable for optimized solar cell applications. The initial growth involves flat-lying copper phthalocyanine molecules in a triclinic brickstone crystal with (012) orientation. Thicker films on pristine graphite, as well as thin films on lower quality graphene, show an orientational transition to the flat-lying (112)-oriented brickstone, which nucleates near film defects and grows in more compact 3D islands. The thi...}, number={9}, journal={CRYSTAL GROWTH & DESIGN}, author={McAfee, Terry and Gann, Eliot and Guan, Tianshuai and Stuart, Sean C. and Rowe, Jack and Dougherty, Daniel B. and Ade, Harald}, year={2014}, month={Sep}, pages={4394–4401} }
 @article{ma_tumbleston_wang_gann_huang_ade_2013, title={Domain Purity, Miscibility, and Molecular Orientation at Donor/Acceptor Interfaces in High Performance Organic Solar Cells: Paths to Further Improvement}, volume={3}, ISSN={["1614-6840"]}, DOI={10.1002/aenm.201200912}, abstractNote={Abstract}, number={7}, journal={ADVANCED ENERGY MATERIALS}, author={Ma, Wei and Tumbleston, John R. and Wang, Ming and Gann, Eliot and Huang, Fei and Ade, Harald}, year={2013}, month={Jul}, pages={864–872} }
 @article{tumbleston_stuart_gann_you_ade_2013, title={Fluorinated Polymer Yields High Organic Solar Cell Performance for a Wide Range of Morphologies}, volume={23}, ISSN={1616-301X}, url={http://dx.doi.org/10.1002/adfm.201300093}, DOI={10.1002/adfm.201300093}, abstractNote={Abstract}, number={27}, journal={Advanced Functional Materials}, publisher={Wiley}, author={Tumbleston, John R. and Stuart, Andrew C. and Gann, Eliot and You, Wei and Ade, Harald}, year={2013}, month={Feb}, pages={3463–3470} }
 @article{mcafee_gann_ade_dougherty_2013, title={Thermally Induced Dewetting in Ultrathin C-60 Films on Copper Phthalocyanine}, volume={117}, ISSN={["1932-7447"]}, DOI={10.1021/jp4067372}, abstractNote={The evolution of thermally annealed ultrathin fullerene–C60 layers on copper phthalocyanine is examined by atomic force microscopy and near-edge X-ray absorption fine structure spectroscopy. Annealing causes C60 films to dewet the copper phthalocyanine substrate surface via lateral surface mass transport. Coarsening of C60 clusters is observed that creates mounds that exceed the nominal C60 thickness by more than an order of magnitude and is consistent with surface diffusion-mediated mass transport. Implications for thermal morphology control in organic solar cells, such as the destabilization of multilayered C60:CuPc with individual layers only ∼5–10 nm thick, are discussed.}, number={49}, journal={JOURNAL OF PHYSICAL CHEMISTRY C}, author={McAfee, T. and Gann, E. and Ade, H. and Dougherty, D. B.}, year={2013}, month={Dec}, pages={26007–26012} }
 @article{yan_collins_gann_wang_ade_mcneill_2012, title={Correlating the Efficiency and Nanomorphology of Polymer Blend Solar Cells Utilizing Resonant Soft X-ray Scattering}, volume={6}, ISSN={["1936-086X"]}, DOI={10.1021/nn204150f}, abstractNote={Enhanced scattering contrast afforded by resonant soft X-ray scattering (R-SoXS) is used to probe the nanomorphology of all-polymer solar cells based on blends of the donor polymer poly(3-hexylthiophene) (P3HT) with either the acceptor polymer poly((9,9-dioctylfluorene)-2,7-diyl-alt-[4,7-bis(3-hexylthien-5-yl)-2,1,3-benzothiadiazole]-2',2"-diyl) (F8TBT) or poly([N,N'-bis(2-octyldodecyl)-11-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-12-bithiophene)) (P(NDI2OD-T2)). Both P3HT:F8TBT and P3HT:P(NDI2OD-T2) blends processed from chloroform with subsequent annealing exhibit complicated morphologies with a hierarchy of phase separation. A bimodal distribution of domain sizes is observed for P3HT:P(NDI2OD-T2) blends with small domains of size ~5-10 nm that evolve with annealing and larger domains of size ~100 nm that are insensitive to annealing. P3HT:F8TBT blends in contrast show a broader distribution of domain size but with the majority of this blend structured on the 10 nm length scale. For both P3HT:P(NDI2OD-T2) and P3HT:F8TBT blends, an evolution in device performance is observed that is correlated with a coarsening and purification of domains on the 5-10 nm length scale. Grazing-incidence wide-angle X-ray scattering (GI-WAXS) is also employed to probe material crystallinity, revealing P(NDI2OD-T2) crystallites 25-40 nm in thickness that are embedded in the larger domains observed by R-SoXS. A higher degree of P3HT crystallinity is also observed in blends with P(NDI2OD-T2) compared to F8TBT with the propensity of the polymers to crystallize in P3HT:P(NDI2OD-T2) blends hindering the structuring of morphology on the sub-10 nm length scale. This work also underscores the complementarity of R-SoXS and GI-WAXS, with R-SoXS measuring the size of compositionally distinguishable domains and GI-WAXS providing information regarding crystallinity and crystallite thickness.}, number={1}, journal={ACS NANO}, author={Yan, Hongping and Collins, Brian A. and Gann, Eliot and Wang, Cheng and Ade, Harald and McNeill, Christopher R.}, year={2012}, month={Jan}, pages={677–688} }
 @article{collins_cochran_yan_gann_hub_fink_wang_schuettfort_mcneill_chabinyc_et al._2012, title={Polarized X-ray scattering reveals non-crystalline orientational ordering in organic films}, volume={11}, ISSN={1476-1122 1476-4660}, url={http://dx.doi.org/10.1038/nmat3310}, DOI={10.1038/nmat3310}, abstractNote={Molecular orientation critically influences the mechanical, chemical, optical and electronic properties of organic materials. So far, molecular-scale ordering in soft matter could be characterized with X-ray or electron microscopy techniques only if the sample exhibited sufficient crystallinity. Here, we show that the resonant scattering of polarized soft X-rays (P-SoXS) by molecular orbitals is not limited by crystallinity and that it can be used to probe molecular orientation down to size scales of 10 nm. We first apply the technique on highly crystalline small-molecule thin films and subsequently use its high sensitivity to probe the impact of liquid-crystalline ordering on charge mobility in polymeric transistors. P-SoXS also reveals scattering anisotropy in amorphous domains of all-polymer organic solar cells where interfacial interactions pattern orientational alignment in the matrix phase, which probably plays an important role in the photophysics. The energy and q-dependence of the scattering anisotropy allows the identification of the composition and the degree of orientational order in the domains.}, number={6}, journal={Nature Materials}, publisher={Springer Nature}, author={Collins, B. A. and Cochran, J. E. and Yan, H. and Gann, E. and Hub, C. and Fink, R. and Wang, C. and Schuettfort, T. and McNeill, C. R. and Chabinyc, M. L. and et al.}, year={2012}, month={Apr}, pages={536–543} }
 @article{gann_young_collins_yan_nasiatka_padmore_ade_hexemer_wang_2012, title={Soft x-ray scattering facility at the Advanced Light Source with real-time data processing and analysis}, volume={83}, ISSN={["1089-7623"]}, DOI={10.1063/1.3701831}, abstractNote={We present the development and characterization of a dedicated resonant soft x-ray scattering facility. Capable of operation over a wide energy range, the beamline and endstation are primarily used for scattering from soft matter systems around the carbon K-edge (∼285 eV). We describe the specialized design of the instrument and characteristics of the beamline. Operational characteristics of immediate interest to users such as polarization control, degree of higher harmonic spectral contamination, and detector noise are delineated. Of special interest is the development of a higher harmonic rejection system that improves the spectral purity of the x-ray beam. Special software and a user-friendly interface have been implemented to allow real-time data processing and preliminary data analysis simultaneous with data acquisition.}, number={4}, journal={REVIEW OF SCIENTIFIC INSTRUMENTS}, author={Gann, E. and Young, A. T. and Collins, B. A. and Yan, H. and Nasiatka, J. and Padmore, H. A. and Ade, H. and Hexemer, A. and Wang, C.}, year={2012}, month={Apr} }
 @article{collins_gann_guignard_he_mcneill_ade_2010, title={Molecular Miscibility of Polymer-Fullerene Blends}, volume={1}, ISSN={["1948-7185"]}, DOI={10.1021/jz101276h}, abstractNote={The device function of polymer bulk heterojunction (BHJ) solar cells has been commonly interpreted to arise from charge separation at discrete interfaces between phase-separated materials and subsequent charge transport through these phases without consideration of phase purity. To probe composition, the miscibility of poly(3-hexylthiophene) (P3HT) and poly(2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylenevinylene) (MDMO-PPV) with phenyl-C61-butyric acid methyl ester (PCBM) has been determined, while the effects of polymer crystallinity on miscibility are probed using P3HT grades of varying regioregularity. It is found that, while no intercalation occurs in P3HT crystals, amorphous portions of P3HT and MDMO-PPV contain significant concentrations of PCBM, calling into question models based on pure phases and discrete interfaces. Furthermore, depth profiles of P3HT/PCBM bilayers reveal that even short annealing causes significant interdiffusion of both materials, showing that under no conditions do pure am...}, number={21}, journal={JOURNAL OF PHYSICAL CHEMISTRY LETTERS}, author={Collins, Brian A. and Gann, Eliot and Guignard, Lewis and He, Xiaoxi and McNeill, Christopher R. and Ade, Harald}, year={2010}, month={Nov}, pages={3160–3166} }