@article{wang_wang_dougherty_2020, title={Direct molecular quantification of electronic disorder in N,N '-Di-[(1-naphthyl)-N,N '-diphenyl]-1,1 '-biphenyl)-4,4 '-diamine on Au(111)}, volume={38}, ISSN={["2166-2754"]}, DOI={10.1116/6.0000401}, abstractNote={Organic light-emitting diodes are important in display applications, but thin films used in these devices often exhibit complex and highly disordered structures. We have studied the adsorption of a typical hole transport material used in such devices, N,N′-Di-[(1-naphthyl)-N,N′-diphenyl]-1,1′-biphenyl)-4,4′-diamine (α-NPD), on the Au(111) surface. Scanning tunneling microscopy images reveal the appearance of different conformations in the first monolayer with submolecular resolution. Scanning tunneling spectra identify the highest occupied molecular orbital on several different adsorption structures. We directly compare the statistical distribution of this orbital energy between an ordered monolayer structure and a disordered bilayer structure of α-NPD on Au(111). The disordered structure exhibits a very broad distribution that is consistent with inferences from prior organic device studies and that we propose arises from minor conformational variations.}, number={5}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Wang, Jiuyang and Wang, Jingying and Dougherty, Daniel B.}, year={2020}, month={Sep} }
 @article{huston_wang_mcafee_loth_anthony_ade_conrad_dougherty_2015, title={Disruption of Molecular Ordering over Several Layers near the Au/2,8-Difluoro-5,11-bis(triethylsilylethynyl) Anthradithiophene Interface}, volume={15}, ISSN={["1528-7505"]}, DOI={10.1021/cg501621k}, abstractNote={The transition from an electrode-dominated ordered monolayer structure to a bulk-like thin film crystal structure of 2,8-difluoro-5,11-bis(triethylsilylethynyl) anthradithiophene (diF-TES-ADT) is observed to occur over at least the first four molecular layers near the electrode surface. Scanning tunneling microscopy studies of the growth of diF-TES-ADT on Au(111) show that the first two molecular layers assemble with aromatic planes parallel to the substrate surface. The monolayer structures are highly stable and well-ordered, while the bilayer structures are more loosely packed and poorly ordered. Subsequent diF-TES-ADT growth results in a more bulk-like layer containing standing up molecular configurations approaching the (001) crystal face as observed by grazing incidence wide angle X-ray scattering measurements. However, the third and fourth monolayers also show poor long-range ordering and an apparent height modulation that indicate significant strain effects from the substrate still persist.}, number={2}, journal={CRYSTAL GROWTH & DESIGN}, author={Huston, Shawn M. and Wang, Jiuyang and McAfee, Terry and Loth, Marsha and Anthony, John E. and Ade, Harald W. and Conrad, Brad R. and Dougherty, Daniel B.}, year={2015}, month={Feb}, pages={822–828} }
 @article{wang_dougherty_2014, title={Extrinsic origins of electronic disorder in 2D organic crystals}, volume={32}, ISSN={["2166-2746"]}, DOI={10.1116/1.4869196}, abstractNote={The dominant impact of extrinsic electronic disorder was observed in α-sexithiophene (α-6T) films grown on C60/Au(111) substrates by scanning tunneling microscopy and spectroscopy measurements. Sexithiophene molecules adopt an upright orientation with a structure that reflects both bulklike α-6T packing and C60 substrate templating effects. Apparent height variations in these films are assigned as molecular sliding defects but are observed to have negligible impact on the energy of the highest occupied molecular orbital. This orbital energy varies more significantly in response to random changes in probe tip, implying that the dominant origin of electronic disorder in two-dimensional organic crystals can be extrinsic to the film.}, number={3}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Wang, Jiuyang and Dougherty, Daniel B.}, year={2014}, month={May} }
 @article{huston_wang_loth_anthony_conrad_dougherty_2012, title={Role of Fluorine Interactions in the Self-Assembly of a Functionalized Anthradithiophene Monolayer on Au(111)}, volume={116}, ISSN={["1932-7455"]}, DOI={10.1021/jp307539q}, abstractNote={Scanning tunneling microscopy studies of the first monolayer of 2,8-difluoro-5,11-(bis)triethylsilylethynyl anthradithiophene on Au(111) reveal two ordered structures with anthradithiophene planes parallel to the substrate. Submolecular resolution STM images demonstrate structures with a close approach of fluorine–sulfur and fluorine–fluorine atoms in the ordered structures. This provides evidence for the importance of noncovalent F–S and F–F in driving 2D self-assembly in the monolayer. Spectroscopic studies indicate a transport gap of 2.4 eV that is insensitive to the local domain structures, as expected for weak intermolecular interactions.}, number={40}, journal={JOURNAL OF PHYSICAL CHEMISTRY C}, author={Huston, Shawn M. and Wang, Jiuyang and Loth, Marsha A. and Anthony, John E. and Conrad, Brad R. and Dougherty, Daniel B.}, year={2012}, month={Oct}, pages={21465–21471} }