In order to tailor the assembling of polymers and organic molecules, a deeper understanding of the kinetics involved in thin film production is necessary. While post-production characterization only provides insight on the final film structure, more sophisticated experimental setups are needed to probe the structure formation processes in situ during deposition. The drying kinetics of a deposited organic thin film strongly influences the assembling process on the nanometer scale. This work presents an experimental setup that enables fine control of the atmosphere composition surrounding the sample during slot die coating, while simultaneously probing the film formation kinetics using in situ grazing incidence X-ray scattering and spectroscopy

Herzig, Eva M

Hexemer, Alexander

Moseguí González, Daniel

Müller-Buschbaum, Peter

Pröller, Stephan

Schaible, Eric

Wang, Cheng

Zhu, Chenhuii

eScholarship - University of California

Lawrence Berkeley National LaboratoryLBL PublicationsTitleNote: Setup for chemical atmospheric control during in situ grazing incidence X-ray scattering of printed thin filmsPermalinkhttps://escholarship.org/uc/item/1kv511q3JournalReview of Scientific Instruments, 88(6)ISSN0034-6748AuthorsPröller, StephanMoseguí González, DanielZhu, Chenhuiiet al.Publication Date2017-06-01DOI10.1063/1.4984130 Peer reviewedeScholarship.org Powered by the California Digital LibraryUniversity of CaliforniaNote: Setup for chemical atmospheric control during in situ grazing incidence X-rayscattering of printed thin filmsStephan Pröller, Daniel Moseguí González, Chenhuii Zhu, Eric Schaible, Cheng Wang, Peter Müller-Buschbaum, Alexander Hexemer, and Eva M. HerzigCitation: Review of Scientific Instruments 88, 066101 (2017); doi: 10.1063/1.4984130View online: http://dx.doi.org/10.1063/1.4984130View Table of Contents: http://aip.scitation.org/toc/rsi/88/6Published by the American Institute of PhysicsArticles you may be interested in Imaging at an x-ray absorption edge using free electron laser pulses for interface dynamics in high energydensity systemsReview of Scientific Instruments 88, 053501 (2017); 10.1063/1.4982166 A physics-based solver to optimize the illumination of cylindrical targets in spherically distributed high powerlaser systemsReview of Scientific Instruments 88, 053503 (2017); 10.1063/1.4979932Generation and application of LET calibration curve for neutron dosimetry using CR-39 detector andmicrowave induced chemical etchingReview of Scientific Instruments 88, 063301 (2017); 10.1063/1.4984621Coarse spectral characterization of warm x-rays at the Z facility using a filtered thermoluminescent dosimeterarrayReview of Scientific Instruments 88, 043501 (2017); 10.1063/1.4979626Analyzing X-ray tomographies of granular packingsReview of Scientific Instruments 88, 051809 (2017); 10.1063/1.4983051A compact two-way power divider based on five-port structureReview of Scientific Instruments 88, 064701 (2017); 10.1063/1.4984294REVIEW OF SCIENTIFIC INSTRUMENTS 88, 066101 (2017)Note: Setup for chemical atmospheric control during in situ grazingincidence X-ray scattering of printed thin filmsStephan Pröller,1 Daniel Moseguı́ González,2 Chenhuii Zhu,3 Eric Schaible,3 Cheng Wang,3Peter Müller-Buschbaum,2 Alexander Hexemer,3 and Eva M. Herzig1,4,a)1Munich School of Engineering, Herzig Group, Technische Universität München, Lichtenbergstr. 4a, 85748Garching, Germany2Physik Department, Lehrstuhl für Funktionelle Materialien, Technische Universität München, James-FranckStr. 1, 85748 Garching, Germany3Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley,California 94720, USA4Experimentalphysik II, Universität Bayreuth, Universitätsstr. 30, 95440 Bayreuth, Germany(Received 21 February 2017; accepted 10 May 2017; published online 1 June 2017)In order to tailor the assembling of polymers and organic molecules, a deeper understanding of thekinetics involved in thin film production is necessary. While post-production characterization onlyprovides insight on the final film structure, more sophisticated experimental setups are needed toprobe the structure formation processes in situ during deposition. The drying kinetics of a depositedorganic thin film strongly influences the assembling process on the nanometer scale. This workpresents an experimental setup that enables fine control of the atmosphere composition surround-ing the sample during slot die coating, while simultaneously probing the film formation kineticsusing in situ grazing incidence X-ray scattering and spectroscopy. Published by AIP Publishing.[http://dx.doi.org/10.1063/1.4984130]The increasing interest in organic electronics (OEs), espe-cially in organic light emitting diodes (OLEDs), organic solarcells (OSCs), and organic field effect transistors (OFETs)demands production possibilities on large scale. As organicsemiconductors can be processed out of solution, up-scalableprinting techniques like slot die coating or spraying are meth-ods of choice for thin film deposition.1,2 For an OSC, thedevice architecture and the resulting inner nano-morphologyare important for the device performance.3,4 Several attemptsaim to manipulate the inner morphology either during process-ing of the active layer or thereafter. The most prominent onesare thermal annealing, solvent additives, or solvent annealing,where especially the latter one is a promising approach.5–7 A3D reconstruction of the final inner structure can, for exam-ple, be obtained using ptychographic X-ray imaging.8 To gaincontrol over the final structure, current interest has movedon to investigate the kinetics during morphology formationusing grazing incidence small and wide angle X-ray scat-tering (GISAXS/GIWAXS). Recently, the first attempt of aslot die coater adaptable to synchrotron beamlines was intro-duced and mechanisms of structure formation of printed filmswere shown.9,10 To understand the self-assembly processes inthin organic films, advanced setups for in situ characterizationimplemented into a synchrotron instrument are required, whilehaving control over various parameters.11–13 In this work, wedesign and fabricate a modular chamber for the slot die coaterthat was previously introduced.9,10 This chamber enables fullcontrol during the printing of thin films while allowing forin situ characterization of the film formation. It is capable ofa)Author to whom correspondence should be addressed: eva.herzig@ph.tum.de.offering and keeping a defined flow of different wet gasescontaining organic solvents with customized partial pressures,featuring the whole range from dry to solvent-saturated gas,which allows for annealing during device processing. Fur-ther control parameters can be used, for example, an externalelectric field or a defined sample stage temperature. Duringprocessing, the morphological development can be trackedin situ with GISAXS, GIWAXS, and optical spectroscopy. Todemonstrate the functionality of the setup, it is implementedinto a synchrotron instrument and the drying of a printed activelayer for OSCs is probed with GISAXS. Additionally, we areable to track the changes in the absorption behavior duringdecelerated solidification.The main part of the presented setup is a chamber, inwhich the sample printing takes place. A diagram of the com-plete printer setup (printing unit and environmental chamber)is depicted in Fig. 1(a), see the supplementary material forfurther images. The presented chamber is generally made ofaluminum plates for good chemical resistance against organicsolvents at low weight. The inner volume is kept small tokeep the time scale of atmosphere control as short as pos-sible. The outer dimensions are around (130 × 300) mm2 witha height of 80 mm except at the outlet window with a heightof 100 mm in order to extend the scattering exit angle rangefor GIWAXS. For weight reduction, all sides exhibit milledpockets but still guarantee a high stability and the possibilityto weld the chamber sides together for high gas tightness. It ismounted above the horizontal motor by spacers carrying theweight and fixing the position of the chamber. The motor iskept outside the chamber to separate the electrical componentsfrom the solvent atmosphere and, concurrently, minimize thevolume of the chamber. The lateral movement of the motorstage is then transferred into the static chamber via rails fixed0034-6748/2017/88(6)/066101/3/$30.00 88, 066101-1 Published by AIP Publishing.066101-2 Pröller et al. Rev. Sci. Instrum. 88, 066101 (2017)FIG. 1. (a) Isometric view of the fully assembled printer setup including the printing unit and the environmental control chamber. (b) Exploded isometric viewof the atmosphere chamber with most important functional parts. (c) Sectional front view on the sample stage and the connection possibilities for optical fibersfor in situ reflectometry or UV-Vis measurements. The orange arrows schematically depict the X-ray path relative to the chamber.on the motor stage and parallel mounted, sealed (Zurcon®Z20, Trelleborg Sealing Solutions) hollow pistons. Inside thechamber, a holder is fixed on these pistons, on which thereis an electrically heatable (up to 150 °C) sample stage thatmoves with the pistons inside the chamber. High performanceresistors are mounted on the bottom of the copper stage andare connected via electrical plugs that are mounted into theend of the hollow pistons and sealed by casting epoxy. Thestage holder is made of polyether ether ketone (PEEK), whichexhibits a low thermal expansion along with a high solventresistivity. The copper stage also works as the bottom elec-trode, which together with a copper top electrode allows for anelectric field during printing. The maximum length of a coatedfilm is 150 mm, which is sufficient for following the film solid-ification process. The heatable print head (Jema TechnologiesLLC) is positioned inside the chamber through an opening inits ceiling. To ensure the tightness, bellows (side) and a printhead holder (top) are used. The holder is made of PEEK for lowheat conduction to the mount and sealed using area seals. Thisallows to vertically move the print head and thereby adjust-ing an accurate print head-to-sample distance (gap clearance),while remaining an atmosphere tight environment inside thechamber. A removable cover that enables the exchange of sam-ples is sealed with a surface seal and fixed with snap locksduring operation. The individual parts and their positions aredepicted in the exploded, isometric view of Fig. 1(b) as wellas in the sectional front view in Fig. 1(c).To produce the desired atmosphere two gas supplies, dryand saturated, respectively, are mixed at a controlled ratio.Solvent-saturated gas is obtained using a washing bottle. Eachpath’s flow is regulated separately using mass flow controllers(red-y smart controller GSC, Vögtlin Instruments AG). After-wards, both supplies are merged to produce a gas mixturein a ratio according to the set flow rates and directed intothe chamber via a nozzle purchased from Lechler GmbH atthe gas inlet. This nozzle provides a defined gas flow abovethe sample. To probe the sample with X-rays, 25.4 µm thickKapton® foils from DuPont are fixed on either side of thechamber. The setup is designed to observe the main charac-teristic crystalline peaks of most semiconducting polymers ofinterest (maximum achievable qz = 18 nm1, qxy = 25 nm1for 10 keV). The remaining windows are covered with glassfor illumination and acquisition of a video signal to be ableto control the process remotely, which is necessary for in situX-ray probing. Further features are the KF flanges mountedon the top and side of the chamber to connect optical fibers toan UV-Vis sender and receiver or a reflectometer, respectively.Hence, either the film thickness or the absorption properties ofthe printed film can be probed while drying. The sectionalfront view in Fig. 1(c) identifies the paths of optical andX-ray characterization. The top fiber is lead through a copperplate which also works as the top electrode for the electricalfield. A hole in the copper sample stage and its holder allowthe UV-Vis signal to pass the stage.Two experiments on the model system poly(3-hexyl-thiophene):[6,6]-phenyl-C61 butyric acid methyl ester (P3HT:PCBM) in chlorobenzene (20 mg/ml, 1:1 ratio), widely usedfor OSCs, are carried out to demonstrate the versatility of theenvironmental chamber. Therefore, as a first experiment, itis implemented into beamline 7.3.3 of the Advanced LightSource (ALS) at Lawrence Berkeley National Laboratory.14The P3HT:PCBM blend is printed on a silicon substrateusing different gas streams flowing above the freshly coatedfilm. The printing parameters are set to a pump rate of250 µl/min, a printing speed of 10 mm/s, and a gap clear-ance of around 300 µm, resulting in a final film thicknessof around 150 nm. Time-resolved GISAXS is performedin situ to track the structure formation while drying with anincident angle of 0.35°, similar to previous studies on this mate-rial,4,10 and a sample-to-detector distance of 1.8 m at 10 keV.Figs. 2(a) and 2(b) depict vertical line cuts of the recorded2D-GISAXS data versus time for a sample printed under aflow of dry helium gas and chlorobenzene saturated heliumgas. The data show a clear difference in the structure forma-tion time for the two different experimental conditions. Dryingunder a dry gas flow shows a rapidly increasing scattering sig-nal, whereas the sample coated under a saturated flow showsinitially a decelerated process, which then rapidly increases ata later stage. The slower drying is expected to influence thestructure formation in a positive manner in terms of solar cellefficiency.7,10The second demonstration experiment shows the suitabil-ity of the implemented optical fibers to record absorptionspectra of the printed films during thin film solidification066101-3 Pröller et al. Rev. Sci. Instrum. 88, 066101 (2017)FIG. 2. Left: Mappings of qz intensity profiles ver-sus time obtained from cuts next to the beam-stop for every single 2D scattering pattern obtainedwith DPDAK.15 The structure formation in the ver-tical direction can be followed. P3HT:PCBM sampleprinted under a constant flow of (a) dry helium and(b) chlorobenzene saturated gas showing a much slowerstructure formation process. The intensity and timescale refer to both datasets. (c) UV-Vis spectra recordedunder a dry gas flow showing the aggregation of theP3HT:PCBM blend film evolving with a time resolutionof 200 ms directly after the printing process. (d) Track-ing of the absorption shoulder of the P3HT crystal atλ = 605 nm for differently chlorobenzene-wetted atmo-spheres as indicated with the arrow.exemplified by printing a P3HT:PCBM film on a glass sub-strate in nitrogen atmosphere. The recorded UV-Vis spectraduring printing are shown in Fig. 2(c). With a time resolution of200 ms, the crystallization process can clearly be followed.After the initial evaporation of the solvent, the polymer crystal-lizes within 10-20 s as seen in the formation of well-establishedshoulders in the UV-Vis spectra at around 605 nm. Usinga chlorobenzene-saturated nitrogen gas stream while print-ing, the onset of the crystallization shoulder is delayed forapproximately 20 s [Fig. 2(d)]. If the gas flow is switched on10 min prior to printing, the solvent partial pressure inside thechamber is able to increase, which yields a delay of even upto nearly double the time compared to the film printed undera dry flow. Thus, the data confirm the proper functioning ofthe atmospheric chamber allowing for customized conditionsof film printing along with comprehensive morphological andspectroscopic system characterizations.In this work, we have designed and built an atmosphericchamber for a slot die coater which can be implemented intoa synchrotron beamline for in situ measurements of the struc-ture formation. Using the presented setup, it is possible totransfer the controlled printing of thin films into a synchrotronbeamline offering a detailed analysis of the fundamentalsof structure formation while controlling the environment toapproach optimized film production conditions. The setupoffers the possibility to simultaneously track either the filmthickness or the absorption properties with a reflectometer andUV-Vis, respectively. The structure formation time of a modelP3HT:PCBM system is reduced by controlling the vapor envi-ronment during printing as seen with in situ GISAXS and UV-Vis absorption measurements. Using the presented setup, theself-assembly process in thin films is controlled by tuning sev-eral macroscopic processing parameters (vapor environment,flow rate of gases, temperature, external electric field, etc.)which enable the production of functional films with enhancedproperties.See supplementary material for further large scale viewsof the chamber.We acknowledge the financial support by the Bavar-ian State Ministry of Education, Science and the Arts viathe project “Energy Valley Bavaria,” from BaCaTec andthe Dr.-Ing. Leonhard-Lorenz-Stiftung. We thank MarcSchönberger and Erik Faber for support and manufacturingthe setup. P.M.-B. and D.M.G. acknowledge financial supportby TUM.solar via “Solar technologies go Hybrid” (SolTec),the GreenTech Initiative (Interface Science for Photovoltaics -ISPV) of the EuroTech Universities, and the Nanosystems Ini-tiative Munich (NIM). Beamline 7.3.3 of the Advanced LightSource is supported by the Director of the Office of Science,Office of Basic Energy Sciences, of the U.S. Department ofEnergy under Contract No. DE-AC02-05CH11231.1R. R. Søndergaard, M. Hösel, and F. C. Krebs, J. Polym. Sci., Part B: Polym.Phys. 51, 16 (2013).2P. Zhang, G. Santoro, S. Yu, S. K. Vayalil, S. Bommel, and S. V. Roth,Langmuir 32, 4251 (2016).3M. A. Brady, G. M. Su, and M. L. Chabinyc, Soft Matter 7, 11065(2011).4W. Wang, S. Pröller, M. A. Niedermeier, V. Körstgens, M. Philipp, B. Su,D. Moseguı́ González, S. Yu, S. V. Roth, and P. Müller-Buschbaum, ACSAppl. Mater. Interfaces 7, 602 (2015).5A. M. Hiszpanski and Y.-L. Loo, Energy Environ. Sci. 7, 592 (2014).6Y. Chen, C. Zhan, and J. Yao, Chem.–Asian J. 11, 2620 (2016).7G. Li, Y. Yao, H. Yang, V. Shrotriya, G. Yang, and Y. Yang, Adv. Funct.Mater. 17, 1636 (2007).8H. F. Dam, T. R. Andersen, E. B. L. Pedersen, K. T. S. Thydén, M. Helgesen,J. E. Carlé, P. S. Jørgensen, J. Reinhardt, R. R. Søndergaard, M. Jørgensen,E. Bundgaard, F. C. Krebs, and J. W. Andreasen, Adv. Energy Mater. 5,1400736 (2015).9F. Liu, S. Ferdous, E. Schaible, A. Hexemer, M. Church, X. Ding, C. Wang,and T. P. Russell, Adv. Mater. 27, 886 (2015).10S. Pröller, F. Liu, C. Zhu, C. Wang, T. P. Russell, A. Hexemer, P. Müller-Buschbaum, and E. M. Herzig, Adv. Energy Mater. 6, 1501580 (2016).11X. Gu, J. Reinspach, B. J. Worfolk, Y. Diao, Y. Zhou, H. Yan, K. Gu,S. Mannsfeld, M. F. Toney, and Z. Bao, ACS Appl. Mater. Interfaces 8,1687 (2016).12L. H. Rossander, N. K. Zawacka, H. F. Dam, F. C. Krebs, andJ. W. Andreasen, AIP Adv. 4, 87105 (2014).13M. Sanyal, B. Schmidt-Hansberg, M. F. G. Klein, A. Colsmann, C. Munuera,A. Vorobiev, U. Lemmer, W. Schabel, H. Dosch, and E. Barrena, Adv.Energy Mater. 1, 363 (2011).14A. Hexemer, W. Bras, J. Glossinger, E. Schaible, E. Gann, R. Kirian,A. MacDowell, M. Church, B. Rude, and H. Padmore, J. Phys.: Conf. Ser.247, 12007 (2010).15G. Benecke, W. Wagermaier, C. Li, M. Schwartzkopf, G. Flucke, R. Hoerth,I. Zizak, M. Burghammer, E. Metwalli, P. Müller-Buschbaum, M. Trebbin,S. Förster, O. Paris, S. V. Roth, and P. Fratzl, J. Appl. Crystallogr. 47, 1797(2014).

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Note: Setup for chemical atmospheric control during in situ grazing incidence X-ray scattering of printed thin films

https://escholarship.org/uc/item/1kv511q3

Note: Setup for chemical atmospheric control during in situ grazing incidence X-ray scattering of printed thin films.

Note: Setup for chemical atmospheric control during in situ grazing incidence X-ray scattering of printed thin films.

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