Developing Enhanced Substrates for OLED SSL

Transcription

1 Developing Enhanced Substrates for OLED SSL DOE SSL R&D Manufacturing Workshop San Diego CA 7 May, 2014 Dr. W. Dennis Slafer MicroContinuum, Inc. 57 Smith Place Cambridge, MA May MicroContinuum 1

2 Outline Company Overview SBIR Program Goals & Technology How Program Benefits OLED SSL 2

3 Company History & Mission Applied chemistry Optics Physics Thin film coating 20 Polaroid Corp Established MicroContinuum in Cambridge, MA Develop Unique Roll-to-Roll Manufacturing Solutions Engineering 3

4 MicroContinuum Programs Patterned Conductors and Dielectrics Hybrid transparent conductors (metal grid/field conductor) TFT, etc. (source, drain electrodes ) Structured Polymer Films Diffractive & microoptics, light-control layers, polymer waveguides Solar Energy Nanoantenna-based energy harvesting Plasmonic light management in thin-film PV Metamaterials Large-area photonic structures for light/signature control Preformatted Substrates for Optical Data Storage optical discs, stripes, tape media (<5 µm thick substrates) Chemistry in Microcups Particle & crystal growth (nano-to-crystalline Si, photographic emulsions), layer transfer 4

5 DOE Phase I SBIR Program Objectives Develop an enhanced flexible substrate for OLED deposition that provides: improved light extraction improved TC performance lower costs 5

6 SBIR Participants MicroContinuum, Inc. Iowa State University (Ames, IA) Dept. of Physics & Microelectronics Research Center: Prof. Joseph Shinar Prof. Rana Biswas Prof. Ruth Shinar 6

7 OLED Issues: >80% of light trapped within OLED stack and substrate Transparent conductor (ITO) shortcomings: limited conductivity & optical transmission roughness (can cause device shorts) crazing, delamination (esp. with flexible substrates) 7

8 Our Approach Develop enhanced working substrate for OLED deposition incorporating: nano- and microstructures to improve internal & external outcoupling new type of transparent conductor that is integrated with the nanoarray 8

9 Improving Internal & External Outcoupling Periodic nanoarrays can effectively extract light trapped (waveguided) within OLED stack Microlens arrays (µla s) can extract light internally reflected at air/substrate interface But to be useful, fabrication process must be cost-effective in large areas requires non-photoresist process 9

10 Example of Periodic Nanoarray (750 pitch nm cones) Pattern replicated in polycarbonate (array pitch ~750 nm x 480 nm height) 10

11 MicroLens Arrays µla Molds (left: 3 µm, right: 30 µm) 11

12 Improving Transparent Conductor Goal is to develop new type of transparent conductor with continuous conductivity: hybrid metal micromesh 12

13 Optical Transmission of Various Grid Patterns (allows >95% open area) W W optical transmission is a function of pitch & line width only substrate wire conductivity (=thickness) is independent of optical transmission 13

14 Metal Mesh with Continuous Conductivity Integrated metal micromesh plus field conductor: higher electrical conductivity and light transmission metal grid provides current-carrying backbone field conductor (FC) provides continuous conductivity over entire surface 14

15 Polymer Flexmasks for Forming Microgrids SEM of additive mask polymeric patterning masks used for additive (top row) and subtractive (bottom row) processing metal & substrate layers patterning masks 15

16 Micromesh Conductive Films metal grid on polyester film (reflection micrograph) 2.5-in Micromesh films offer higher performance and lower cost than conventional transparent conductive films 16

17 Hybrid Micromesh: Integrated Field Conductor AgNWs Aluminum grid (15 µm) with ITO field conductor (5 mil Mylar substrate) [all images by polarized light reflection microscopy] aluminum grid with silver nanowire field conductor 17

18 Summary of New TC Optical and electrical properties not coupled grid transmission determined by geometry conductivity determined by metal & thickness optical transmission independent of wire thickness any metal: Al, Ag, Cu, Mo, Au, Ti Minimal performance required for field conductor can use PEDOT:PSS, AgNW, ultra-thin ITO, other TCO s 18

19 Summary: Benefits for OLED SSL Reduced Costs All steps are R2R high throughput nano- and micro-patterning (>10 FPM) non-photoresist = minimal materials costs and processing steps Simplifies OLED Deposition extraction/tc structures formed off-line isolates processing from OLED deposition Improved Performance higher light output (extraction >70%) better output uniformity higher current-carrying capacity 19

20 Latest SBIR Results: First Integrated Structure Aluminum wire modulated by nanoarray (top: low mag optical micrograph of metal line on diffractive field; left 20 µm line in reflection mode; right-same line viewed in transmission) 20

21 Our thanks to DOE for its support! Award: DE-SC : R2R Production of Low-Cost Integrated OLED Substrate with Improved Transparent Conductor and Enhanced Light Outcoupling W. Dennis Slafer