Analysis of Wet Coating Thickness Effect on Transparent Conductive Electrode Performance using Silver Nanowire 2017. 04. 25 Seung-Hyun Lee, PhD Senior Researcher Dept. Printed Electronics Korea Institute of Machinery and Materials, 171 Jang-Dong, Yuseong-Gu, Daejeon, 305-343, KOREA Email: shlee79@kimm.re.kr R2R Printed Electro-Mechanical System 1/29
Development Trends in Electronics Low-cost Ubiquitous Large area Flexibility Tomorrow Future Today Rigid flat display RFID Smart card E-paper Digital signage Disposable electronics Wearable electronics Deformable batteries Deformable display
Development Trends in Electronics 2015 2020 : IoT, Wearable, Flexible era. Common characteristics IoT Smartpackage market Size Large -> Large area patterning Demand High -> Mass production Precision medium -> Several or tens of micron Price cheap -> Cheap process Flexibility -> Plastic or paper substrate Solar cell Solar cell market Roll printing system, Gravure printing, flexo printing, InkJet printing, screen printingmicro contact printing, pad printing, R2R printing system Flexible diaply Display market
Paradigm Shift in Manufacturing Process Photolithography Complex process Long production time High cost equipment Large material consumption Rigid substrates VS Printing process No vacuum deposition / No photolithography Simple process Applicable to various substrates Lower fabrication costs Mass production (R2R)
Applications of Printed Electronics Printed Memory Printed Transistor Printed Battery and Display Applications 활용분야 Printed Antenna Printed Solar Cell Printed RFID Tag Touch Screen <Ref :Oe-A>
Applications of Printed Electronics Flexible Display Printed Solar Cell Portable Solar Cell RFID Tag Printed RFID Antenna
Dept. Printed Electronics @ KIMM History Personnel Topics Applications : abundant experiences over ten years in media printing processes and equipments : 35 full-time researchers related to printing technologies : mainly focused on printing processes and equipments (R2R gravure, Reverse-offset, Inkjet, ESD, Screen, Slot-die Coating, Micro-gravure Coating) : major research and development activities are oriented to industrial applications such as RFID tag, Solar cell(opv, CIGS), Touch screen panel, Supercapacitor, OLED, and Flexible display Materials Equipment Processin g & Analysis Functional electronic devices - Synthesis of NPs - E-ink (paste) formulation - Fine tuning for ink printability - Etc. - Reverse (offset) - (R2R) Gravure (offset) - (R2R) Slot-die coating - (R2R) Imprinting - Spin / Bar coating - Screen printing - Etc. - (R2R) IPL - (R2R) UV/NIR/MIR - (R2R) Plasma treatment - Multi-measurement system - UV-VIS spectroscopy - Solar simulator - Probe station - Etc. Development of large area & low cost electronics OPV / OLED / TFT / RFID / Sensors / Supercapacitor / Etc.
Dept. Printed Electronics @ KIMM Development of Roll-to-roll Printing Process & System Multi R2R Printing System (Gravure, Gravure-offset, Flexo Printing) Applications Touch screen panel, Color filter for LCD, E-paper, RFID, Solar cell, Flexible display etc. Low price & mass production of electronic devices. 96bit RFID antenna pattern with Ag nano ink
Dept. Printed Electronics @ KIMM Development of Roll-to-roll Coating Process & System R2R Slot-die Coating & Screen Printing System for OPV & TSP R2R Slot-die Coating System For Thin Film Supercapacitor Organic Solar Cells (Slot-die Coating & Screen Printing) Thin Film Supercapacitor
Dept. Printed Electronics @ KIMM Development of Roll-to-roll Imprinting Process & System R2R UV Imprinting System for Optical Film R2R Thermal Imprinting System for TCE
Dept. Printed Electronics @ KIMM MOU with PARC MOU with HP MOU with MGUP MOU with RISO MOU with Kent Univ.
Trend in TCE in Various Electronics
Trend in TCE in Various Electronics 13
Trend in TCE in Various Electronics
Trend in TCE in Various Electronics As is OLED Display Solar cell Based on glass (rigid) substrate / expensive material & process / To-be Deformable lightings Deformable displays Flexible, large area solar cells Wearable electronics Deformable battery + Multi-function (Integration)
Trend in TCE in Various Electronics Problem of ITO High Resistance (>150 Ω/sq) Low Transparency (<87%) High Cost : Sputtering (>$80/ m2 ) Brittle, Low Flexibility Market Needs Low Resistance : <30 Ω/sq High Transparency : >89% Low Cost : R2R Wet Coating High Flexibility Need for New Flexible Transparent Conductive Electrode : High Performance AgNW TCE by R2R Coating ClearOhm TM Silver Nanowire Ref: Cambrios Website 23 LG V325 All-in-One PC
Experimental Details Ink Supply Wet film Substrate moving Schematic of Slot-die Coating Process Slot-die Coating System
Experimental Results wet thickness 5 6 7 8 9 10 11 12 13 14 15 17 20 25 30 40 50, tw (um) Sheet Resistance, Rs (Ω/ ) 353 248 183 156 121 101 89.1 83.7 62.8 57.4 50.1 44.1 35.9 28.4 19.0 13.2 10.2 Transparency, T (%) Haze, H (%) 92.6 92.4 92.1 91.9 91.8 91.7 91.7 91.1 91.1 90.9 90.2 90.3 90.0 89.0 88.5 86.9 85.5 0.68 0.69 0.83 0.85 0.97 1.10 1.18 1.32 1.34 1.40 1.60 1.80 1.97 2.39 2.66 3.69 4.75 * Measured Transparency & Haze including substrate
Experimental Results T (%) 93.00 92.00 91.00 90.00 89.00 88.00 87.00 86.00 85.00 Rs vs T 0.00 100.00 200.00 300.00 400.00 Rs (Ω/ ) T Ag (%) 100 99 98 97 96 95 94 93 92 91 90 Rs (Ω/ ) 400.00 350.00 300.00 250.00 200.00 150.00 100.00 50.00 0.00 10 40 160 Rs (Ω/ ) H vs Rs 0.00 1.00 2.00 3.00 4.00 5.00 H (%) T Ag is calculated transparency based on PET film (without PET)
Experimental Results T (%) 1-T Ag 93.00 92.00 91.00 90.00 89.00 88.00 87.00 86.00 85.00 0 10 20 30 40 50 60 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0.00 0 20 40 60 t w (um) t w (um) H Ag 5.00 4.50 4.00 3.50 3.00 2.50 2.00 1.50 1.00 0.50 0.00 H(%) 5.00 4.50 4.00 3.50 3.00 2.50 2.00 1.50 1.00 0.50 0.00 0 10 20 30 40 50 60 0 20 40 60 t w (um) t w (um)
Experimental Results 400.00 3.000 Rs (Ω/ ) 350.00 300.00 250.00 200.00 150.00 100.00 50.00 Log(Rs) (Ω/ ) 2.500 2.000 1.500 1.000 0.500 1.53 = 3600 wet R s t 0.00 2500 0 10 20 30 40 50 60 t w (um) 전도도 - 두께 0.000 0.600 1.100 1.600 2.100 Log(t w) (um) 2000 1500 1000 500 σ DC = 1 R s t film 1 R s t wet t 0.53 w 0 0 10 20 30 40 50 60 Conductivity is not constatnt with film thickness : Transition (Network => Bulk) S. De et al. ACS Nano, 2009
Conclusions Pre-metered slot-die coating can easily control wet thickness of AgNW conductive film by changing web speed and flow rate Very high performance TCE were fabricated by using AgNW with high aspect ratio AgNW (T ~ 92%, Rs ~ 120Ω/, H < 1%) In range of Rs <10Ω/, conductivity is not constant due to percolation effect (σ DC ~ t 0.53 ) By controlling wet thickness of AgNW film, we can easily control and estimate the TCE performance such as sheet resistance, transparency and haze
Seung-Hyun Lee, PhD Senior Researcher Korea Institute of Machinery and Materials, 171 Jang-Dong, Yuseong-Gu, Daejeon, KOREA 305-343 Email: shlee79@kimm.re.kr