Abstract
The key challenge in solution-processing efficient OLEDs is to realize the multilayer device architecture. We demonstrate that slot die coating is applicable to deposit small-molecule (SM) layers on top of each other without dissolving the underlying layer. A stack for a blue SMOLED is chosen comprising slot die-coated PEDOT:PSS, an SM emissive layer (EML) as well as an SM electron transport layer (ETL). The devices are fabricated in a sheet-to-sheet coating process with a slot die table coater under ambient conditions. While keeping the processing parameters constant for PEDOT:PSS and the EML, the composition of the ETL is varied. The choice of solvent for coating the ETL is crucial regarding wetting and dissolution of the underlying layer, solubility, surface roughness, and device efficiencies. Average roughness values down to 0.38 nm and peak to valley values around 10 nm were measured. Comparing device efficiencies of devices with and without ETL, an increase in efficiency with a factor up to 42 was achieved. In total, we show 135 blue SMOLEDs to demonstrate reproducibility.
Similar content being viewed by others
Abbreviations
- AA:
-
Acetic acid
- Al:
-
Aluminum
- CE:
-
Current efficiency
- EML:
-
Emissive layer
- ETL:
-
Electron transport layer
- EtOH:
-
Ethanol
- FA:
-
Formic acid
- FIrPic:
-
Bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyr-idyl)iridium(III)
- HBL:
-
Hole blocking layer
- HIL:
-
Hole injection layer
- HTL:
-
Hole transport layer
- ITO:
-
Indium-tin-oxide
- LiF:
-
Lithiumfluoride
- MeOH:
-
Methanol
- PE:
-
Power efficiency
- Prop:
-
Propanol
- SimCP2:
-
Bis[3,5-di(9H-carbazol-9-yl)phenyl]diphenylsilane
- Tol:
-
Toluene
- TPBi:
-
2,2′,2″-(1,3,5-Benzinetriyl)-tris(1-phenyl-1-H-benzimidazole)
References
You, J, Tseng, S, Meng, H, Yen, F, Lin, I, Horng, S, “All-Solution-Processed Blue Small Molecular Organic Light-Emitting Diodes with Multilayer Device Structure.” Organ. Electron., 10 (8) 1610–1614 (2009)
Xue, S, Qiu, X, Yao, L, Wang, L, Yao, M, Gu, C, Wang, Y, Xie, Z, Wu, H, “Fully Solution-Processed and Multilayer Blue Organic Light-Emitting Diodes Based on Efficient Small Molecule Emissive Layer and Intergrated Interlayer Optimization.” Organ. Electron., 27 35–40 (2015)
Henwood, AF, Bansal, AK, Cordes, DB, Slawin, AMZ, Samuel, IDW, Zysman-Colman, E, “Solubilised Bright Blue-Emitting Iridium Complexes for Solution Processed OLEDs.” J. Mater. Chem. C Mater. Opt. Electron. Devices, 4 (17) 3726–3737 (2016)
Duan, L, Hou, L, Lee, T, Qiao, J, Zhang, D, Dong, G, Wang, L, Qiu, Y, “Solution Processable Small Molecules for Organic Light-Emitting Diodes.” J. Mater. Chem., 20 (31) 6392 (2010)
Choi, K, Lee, J, Park, J, Seo, Y, “Multilayer Slot-Die Coating of Large-Area Organic Light-Emitting Diodes.” Organic Electronics, 26 66–74 (2015)
Choi, K, Lee, J, Shin, D, Park, J, “Investigation on Slot-Die Coating of Hybrid Material Structure for OLED Lightings.” J. Phys. Chem. Solids, 95 119–128 (2016)
Carvalho, MS, Kheshgi, HS, “Low-Flow Limit in Slot Coating: Theory and Experiments.” AIChE J., 46 (10) 1907–1917 (2000)
Kistler, SF, Schweizer, PM (eds.), Liquid Film Coating. Springer, Netherlands, Dordrecht (1997)
Han, GH, Lee, SH, Ahn, W, Nam, J, Jung, HW, “Effect of Shim Configuration on Flow Dynamics and Operability Windows in Stripe Slot Coating Process.” J. Coat. Technol. Res., 11 (1) 19–29 (2014)
Schmitt, M, Scharfer, P, Schabel, W, “Slot Die Coating of Lithium-Ion Battery Electrodes. Investigations on Edge Effect Issues for Stripe and Pattern Coatings.” J. Coat. Technol. Res., 11 (1) 57–63 (2014)
Schmitt, M, Diehm, R, Scharfer, P, Schabel, W, “An Experimental and Analytical Study on Intermittent Slot Die Coating of Viscoelastic Battery Slurries.” J. Coat. Technol. Res., 12 (5) 927–938 (2015)
Kang, H, Park, J, Shin, K, “Statistical Analysis for the Manufacturing of Multi-Strip Patterns by Roll-to-Roll Single Slot-Die Systems.” Robot. Comput. Integr. Manuf., 30 (4) 363–368 (2014)
Lin, C, Wang, B, Lo, S, Wong, DS, Liu, T, Tiu, C, “Operating Windows of Stripe Coating.” Asia Pac. J. Chem. Eng., 9 (1) 134–145 (2014)
Wen, S, Liu, T, “Extrusion Die Design for Multiple Stripes.” Polym. Eng. Sci., 9 (35) 759–767 (1995)
Larsen-Olsen, TT, Andreasen, B, Andersen, TR, Böttiger, AP, Bundgaard, E, Norrman, K, Andreasen, JW, Jørgensen, M, Krebs, FC, “Simultaneous Multilayer Formation of the Polymer Solar Cell Stack Using Roll-to-Roll Double Slot-Die Coating from Water.” Sol. Energy Mater. Sol. Cells, 97 22–27 (2012)
Horiuchi, R, Suszynski, WJ, Carvalho, MS, “Simultaneous Multilayer Coating of Water-Based and Alcohol-Based Solutions.” J. Coat. Technol. Res., 12 (5) 819–826 (2015)
Ji, HS, Ahn, W, Kwon, I, Nam, J, Jung, HW, “Operability Coating Window of Dual-Layer Slot Coating Process Using Viscocapillary Model.” Chem. Eng. Sci., 143 122–129 (2015)
Schmitt, M, Raupp, S, Wagner, D, Scharfer, P, Schabel, W, “Analytical Determination of Process Windows for Bilayer Slot Die Coating.” J. Coat. Technol. Res., 12 (5) 877–887 (2015)
Schmitt, M, Baunach, M, Wengeler, L, Peters, K, Junges, P, Scharfer, P, Schabel, W, “Slot-Die Processing of Lithium-Ion Battery Electrodes—Coating Window Characterization.” Chem. Eng. Process. Process Intensif., 68 32–37 (2013)
Yang, CK, Wong, DSH, Liu, TJ, “The Effects of Polymer Additives on the Operating Windows of Slot Coating.” Polym. Eng. Sci., 44 (10) 1970–1976 (2004)
Ding, X, Liu, J, Harris, TA, “A Review of the Operating Limits in Slot Die Coating Processes.” AIChE J., 62 (7) 2508–2524 (2016)
Romero, OJ, Carvalho, MS, “Response of Slot Coating Flows to Periodic Disturbances.” Chem. Eng. Sci., 63 (8) 2161–2173 (2008)
Carlé, JE, Andersen, TR, Helgesen, M, Bundgaard, E, Jørgensen, M, Krebs, FC, “A Laboratory Scale Approach to Polymer Solar Cells Using One Coating/Printing Machine, Flexible Substrates, No ITO, No Vacuum and No Spincoating.” Sol. Energy Mater. Sol. Cells, 108 126–128 (2013)
Dam, HF, Krebs, FC, “Simple Roll Coater with Variable Coating and Temperature Control for Printed Polymer Solar Cells.” Sol. Energy Mater. Sol. Cells, 97 191–196 (2012)
Hösel, M, Søndergaard, RR, Jørgensen, M, Krebs, FC, “Fast Inline Roll-to-Roll Printing for Indium-Tin-Oxide-Free Polymer Solar Cells Using Automatic Registration.” Energy Technol., 1 (1) 102–107 (2013)
Krebs, FC, “Fabrication and Processing of Polymer Solar Cells. A Review of Printing and Coating Techniques.” Sol. Energy Mater. Sol. Cells, 93 (4) 394–412 (2009)
Roth, B, dos Reis Benatto, GA, Corazza, M, Søndergaard, RR, Gevorgyan, SA, Jørgensen, M, Krebs, FC “The Critical Choice of PEDOT:PSS Additives for Long Term Stability of Roll-to-Roll Processed OPVs.” Adv. Energy Mater., 5 (9) 1401912 (2015)
Liu, F, Ferdous, S, Schaible, E, Hexemer, A, Church, M, Ding, X, Wang, C, Russell, TP, “Fast Printing and In Situ Morphology Observation of Organic Photovoltaics Using Slot-Die Coating.” Adv. Mater. (Deerfield Beach, Fla.), 27 (5) 886–891 (2015)
Pröller, S, Liu, F, Zhu, C, Wang, C, Russell, TP, Hexemer, A, Müller-Buschbaum, P, Herzig, EM, “Following the Morphology Formation In Situ in Printed Active Layers for Organic Solar Cells.” Adv. Energy Mater., 6 (1) 1501580 (2016)
Wengeler, L, Peters, K, Schmitt, M, Wenz, T, Scharfer, P, Schabel, W, “Fluid-dynamic properties and wetting behavior of coating inks for roll-to-roll production of polymer-based solar cells.” J. Coat Technol. Res., 11 (1) 65–73 (2014)
Chang, J, Chi, C, Zhang, J, Wu, J, “Controlled Growth of Large-Area High-Performance Small-Molecule Organic Single-Crystalline Transistors by Slot-Die Coating Using a Mixed Solvent System.” Adv. Mater., 25 (44) 6442–6447 (2013)
Chang, J, Lin, Z, Li, J, Lim, SL, Wang, F, Li, G, Zhang, J, Wu, J, “Enhanced Polymer Thin Film Transistor Performance by Carefully Controlling the Solution Self-Assembly and Film Alignment with Slot Die Coating.” Adv. Electron. Mater., 1 (7) 1500036 (2015)
Sandström, A, Dam, HF, Krebs, FC, Edman, L, “Ambient Fabrication of Flexible and Large-Area Organic Light-Emitting Devices Using Slot-Die Coating.” Nat. Comms., 3 1002 (2012)
Park, B, Kwon, OE, Yun, SH, Jeon, HG, Huh, YH, “Organic Semiconducting Layers Fabricated by Self-Metered Slot-Die Coating for Solution-Processable Organic Light-Emitting Devices.” J. Mater. Chem. C, 2 (40) 8614–8621 (2014)
Raupp, SM, Merklein, L, Pathak, M, Scharfer, P, Schabel, W, “An Experimental Study on the Reproducibility of Different Multilayer OLED Materials Processed by Slot Die Coating.” Chem. Eng. Sci., 160 113–120 (2017)
Raupp, SM, Daume, D, Tekoglu, S, Merklein, L, Lemmer, U, Hernandez-Sosa, G, Sauer, HM, Dörsam, E, Scharfer, P, Schabel, W, “Slot Die Coated and Flexo Printed Highly Efficient SMOLEDs.” Adv. Mater. Technol., 2 (2) 1600230 (2017)
Meerholz, K, “Device Physics: Enlightening Solutions.” Nature, 437 (7057) 327–328 (2005)
Chang, Y, Chiu, Y, Chang, H, Wang, Y, Shih, Y, Wu, C, Liu, Y, Lin, Y, Meng, H, Chi, Y, Huang, H, Tseng, M, Lin, H, Zan, H, Horng, S, Juang, J, “Interface and Thickness Tuning for Blade Coated Small-Molecule Organic Light-Emitting Diodes with High Power Efficiency.” J. Appl. Phys., 114 (12) 123101 (2013)
Chang, H, Lee, Y, Tseng, M, Jang, M, Yeh, H, Luo, F, Meng, H, Chen, C, Chi, Y, Qiu, Y, Duan, L, Lin, H, Horng, S, Zan, H, “General Application of Blade Coating to Small-Molecule Hosts for Organic Light-Emitting Diode.” Synth. Met., 196 99–109 (2014)
Liu, S, Yuan, C, Yeh, S, Wu, M, Chen, C, Lee, C, “Efficiency Enhancement of Solution-Processed Single-Layer Blue-Phosphorescence Organic Light-Emitting Devices Having Co-host Materials of Polymer (PVK) and Small-Molecule (SimCP2).” J. Soc. Inf. Display, 19 (4) 346 (2011)
Knauer, KA, Najafabadi, E, Haske, W, Kippelen, B, “Inverted Top-Emitting Blue Electrophosphorescent Organic Light-Emitting Diodes with High Current Efficacy.” Appl. Phys. Lett., 101 (10) 103304 (2012)
Bhansali, US, Polikarpov, E, Swensen, JS, Chen, W, Jia, H, Gaspar, DJ, Gnade, BE, Padmaperuma, AB, Omary, MA, “High-Efficiency Turquoise-Blue Electrophosphorescence from a Pt(II)-Pyridyltriazolate Complex in a Phosphine Oxide Host.” Appl. Phys. Lett., 95 (23) 233304 (2009)
Acknowledgments
The authors acknowledge financial support via the project Print OLED (Contract Number 13N10759) and POESIE (Contract Number 13N13692) of the Federal Ministry of Education and Research. We would like to thank all involved mechanics, assistants, and our students for contributing to this work as well as TSE Troller AG, Murgenthal, Switzerland, for technical support. The authors are also thankful for the support of the Light Technology Institute (LTI) of KIT as well as the Institute of Printing Science (IDD) of the Technical University of Darmstadt and InnovationLab GmbH, Heidelberg.
Author information
Authors and Affiliations
Corresponding author
Electronic supplementary material
Below is the link to the electronic supplementary material.
Rights and permissions
About this article
Cite this article
Raupp, S.M., Merklein, L., Hietzschold, S. et al. Slot die-coated blue SMOLED multilayers. J Coat Technol Res 14, 1029–1037 (2017). https://doi.org/10.1007/s11998-017-9964-z
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11998-017-9964-z