Samuel Graham. Acknowledgements

Transcription

1 Development of Barrier Films for Packaging Flexible Electronics Samuel Graham Woodruff School of Mechanical Engineering School of Materials Science and Engineering Center for Organic Photonics and Electronics Georgia InsDtute of Technology Acknowledgements Students/ Post Docs Hyungchul Kim, Anuradha Bulusu, Ankit Singh, Amir Dindar, Cheng Wang, Hendrick Bahre (Ruhr University Bochum) FACULTY/ Research Groups Bernard Kippelen, Canek Fuentes Hernandez (Georgia Tech) Olivier Pierron (Georgia Tech) Joerg Winter (Ruhr University Bochum) Adriana Creatore (TU Eindhoven) Sponsors NSF, DOE Bay Area Photovoltaics ConsorPum, Applied Materials, SRC 1

2 ApplicaPons of Barrier Layers: Organic Electronics Electrochromics Solid State Lighting Solar Cells Flexible Transistors Challenges for Other Devices Exposure to moisture can cause degradapon in both OLED and inorganic SSL technologies, thin film PV, and sensors. 2

3 OTR [cm 3 /m 2 /day/atm] E E E E E E E OPVs 1.0E CIGS Barrier Film Requirements 1.0E E E E E E E E E E E E+03 Single Layer and MulDlayer Films Requirement of OLEDs Food / PharmaceuDcal packaging WVTR [g/m 2 /day] Commercial polymer (PET, PEN) Inorganic coated polymers Polymer films Food packaging Organic electronics G. Dennler, et. al., J. Mater. Res., Vol. 20, No. 12, Dec Vol.20, 3224 Defects and Structure in Barrier Films Goal: Defect Free Films with High Density R q = 4.9 nm Al 2 O 3 by ALD R q = 1.1 nm R q = 0.49 nm Voids 100 nm 40 nm Grain boundary Channel H 2 O 100 nm 1 µm SiN x (100nm) on PMMA coated PET 0.3 nm DeposiDon surface greatly impacts the structure of the barrier film. 3

4 ALD- based Hybrid Barriers Low- cost, flexible encapsula0on for thin- film PV ALD- based hybrid barriers: Coupling layer: MiDgate Surface Defects and Control ALD NucleaDon Materials: Range of metal oxides Create monolithic or nanolaminate films of stable ALD layers with Al 2 O 3 at 100 o C. Atomic Layer Deposi0on (ALD): Ultra- thin (<50 nm) conformal and flexible ceramic barriers WVTR < 10-5 g/m 2 - day SpaEal ALD: high throughput, cost efficient to address manufacturing Permea0on Analysis and Defect Detec0on polymer substrate barrier film calcium Glass substrate Laminated Barrier Transparent adhesive tape Test in an environmental chamber at 85 C/85%RH 22 hr 48 hr 148 hr 192 hr Direct DeposiDon barrier film calcium Glass substrate 4

5 Barrier Layer EvoluDon Sample A: Nanolaminate Structure Sample B: Nanolaminate Structure Si Nanolaminate Structure 1 0 n m Sharp interfaces in nanolaminate No change in chemical structure aeer damp heat exposure for two weeks. Sample 50 C/85% RH for 10 days 200 nm Cytop 780 nm Cytop 1000 nm Cytop 4300 nm Cytop Day 0 Day 3 Day 10 5

6 Cracks in Barrier Films 1) Cracks developed with increasing thickness of Cytop opened large areas in the barrier film for water permeapon 2) Local degradapon rate from cracks was much more than that due to cracks Sample RH 200 nm Cytop 780 nm Cytop 1000 nm Cytop 4300 nm Cytop Day 20 Day 1 6

7 SpaDal ALD of Barrier Films Collaborate with TNO/Holst Centre- Eindhoven, NL Visit to TNO/Holst Center to deposit ALD layers on PECVD SiNx. DeposiPon of 10 nm ALD layers occurred within 10 minutes at 100 C using rotary reactor. Roll- to- Roll system is expected to take approximately 1 minute compared to 3-4 hours in viscous flow reactor. 150 mm Laminated Samples Polymer (or glass) substrate barrier film calcium Glass substrate PIB sealant ALD SiNx (250 nm) Substrate (PEN/PET) Sample in an environmental chamber at 85 C/85%RH 23 hr 40 hr 112 hr 192 hr Calcium No nodceable change at least for ~200 hr at 85 C/85%RH 7

8 Mechanical Reliability: Strain To Failure Mechanical TesDng Using Laser Scanning Confocal Microscopy OpDcal Microscopy SiNx Coated PET 0% 1% 19% Al 2 O 3 on PEIE Coated PET Extending the Performance of Briile Barriers Designing the architecture such that you place the barrier on the neutral axis can reduce the strain on the film and improve performance under flexural deformadon. Barrier on Top Barrier on Neutral Axis GT logo for eye inspecpon Afer bending: R= 5mm 10 min 2 days SoluDon deposited barriers and changes in material chemistry also provide routes to mechanically flexible barrier technologies. N. Kim and S. Graham, Thin Solid Films,