Flexible optical system for large-area LED luminaires with excellent light uniformity and efficiency

Flexible optical system for large-area LED luminaires with excellent light uniformity and efficiency R. Ferrini, O. Fernandez, F. Zanella, M. Stalder, B. Gallinet SPIE Photonics West, 11.02.2015

Centre Suisse d Electronique et Microtechnique (CSEM) CSEM at a glance Our mission Development and transfer of microtechnologies to the industrial sector in Switzerland, as a priority in order to reinforce its competitive advantage Cooperation agreements with established companies Creation of start-ups Copyright 2015 CSEM Large Area Solid State Intelligent Efficient luminaires LASSIE-FP7 (lassie-fp7.eu) Page 1

Outline Large area solid-state lighting: LEDs and OLEDs The hybrid solution (LASSIE-FP7) Building-blocks Flexible optical system for light management Conclusions Copyright 2015 CSEM Large Area Solid State Intelligent Efficient luminaires LASSIE-FP7 (lassie-fp7.eu) Page 2

Solid-state lighting: LEDs and OLEDs Lighting quality Black body Philips NR63 Hybrid OLED CCT = 3900K CCT = 3900K / CRI < 70 CCT = 3600K M. Schaer, P. Cotte, L.Zuppiroli (Lumières du Futur, PPUR, 2011) We need a new definition and measure of lighting quality beyond CRI based on the whole source spectral characteristics of SSL sources Copyright 2015 CSEM Large Area Solid State Intelligent Efficient luminaires LASSIE-FP7 (lassie-fp7.eu) Page 4

Solid-state lighting: LEDs and OLEDs Commercial LED & OLED lighting modules Philips Fortimo Philips Lumiblade LG Chem Copyright 2015 CSEM Large Area Solid State Intelligent Efficient luminaires LASSIE-FP7 (lassie-fp7.eu) Page 5

Solid-state lighting: LEDs and OLEDs Commercial LED & OLED lighting modules LEDs OLEDs Philips LG Chem LG Chem Highest lumen output 1 Philips Largest Area Highest Efficacy Best commercial module Fortimo LED DLM 5000 55W/830 Gen5 Lumiblade Brite FL300 N6SD30 N8SA30 Emissive area (mm 2 ) 2 940 2 102x102 320x320 100x100 Thickness (mm) 43.6 2 3.0 1 1.0 1 1.97 1 Luminous flux (lm) 4 500-5 500 300 2 850 2 75 Lumen Efficacy (lm/w) 100 3 79 4 >50 3 60 80 CCT (K) 3 000 3 000 4 3 000 3 000 CRI >80 >80 >90 >80 Lifetime LT70 10 (10 3 50 hrs) 50 6 40 3,4 50 2 Price / unit 69 EUR 5 136 EUR 60 EUR 7 Unknown 82 EUR 3 1 Other products exist with lower lm 2 Based on the technical drawings 3 Module 4 System 5 ebay (source) 1 Including thermal backplate, housing and wiring 2 At 340mA and 19V 3 At 300 lumen 4 4000K planned 5 At 300 lumen 6 At 125 lumen 7 For orders above 40 OLEDs 1 Bare OLED 2 At 1700mA and 8.5V 3 At 3 000 cd/m2 4 Using LG proprietary Face Seal technology Luminous flux (lm/eur): LEDs >> OLEDs more than one order of magnitude 1 With housing and wiring 2 Initial luminance not specified 3 Source Copyright 2015 CSEM Large Area Solid State Intelligent Efficient luminaires LASSIE-FP7 (lassie-fp7.eu) Page 6

Solid-state lighting: LEDs and OLEDs SSL tomorrow : OLEDs will complement LED lighting IHS : OLED lighting market 26 Mio. $ in 2020 IDTechEx : OLED lighting market 200 Mio. $ in 2019 / 1.9 Bio. $ in 2025 UBI Research : OLED lighting market 4.7 Bio. $ in 2020 Source: OLED-Info OLED lighting will come but when and how? Copyright 2015 CSEM Large Area Solid State Intelligent Efficient luminaires LASSIE-FP7 (lassie-fp7.eu) Page 7

Solid-state lighting: LEDs and OLEDs SSL today : how to improve the quality of LED lighting? CTI Project «New Color-changing films for lighting applications» (nr. 8184.1 EPRP-IW) 2006-2008 Patents o EP08164280.3 & US 2010/0102251 o US 13/114.558 & PCT/IB2012/052577 Copyright 2015 CSEM Large Area Solid State Intelligent Efficient luminaires LASSIE-FP7 (lassie-fp7.eu) Page 8

LED-based polymer foils Opportunities LED-based polymer foils Flexible lighting modules Printing and assembly with R2R processes Improved performance: o Optimized electronics layout o Traditional electronic SMD components o Bare LEDs with no on-chip optics Challenges Heat management o Poor thermal conductivity of the polymer foils Copyright 2015 CSEM Large Area Solid State Intelligent Efficient luminaires LASSIE-FP7 (lassie-fp7.eu) Page 10

Heat management: Simulation & Test Simulation Thermal model (Comsol / FEM) Test structures Processing The model was set-up to represent the test structures Test structures: circuits with vias & slugs Copyright 2015 CSEM Large Area Solid State Intelligent Efficient luminaires LASSIE-FP7 (lassie-fp7.eu) Page 11

Heat management: Measurements Thermal transient tests Modelling Sensitive to the thermal conductivity of the PET foil Measurement Forward voltage LED temperature Vias work well but requires further development Slugs provide the best thermal performance Copyright 2015 CSEM Large Area Solid State Intelligent Efficient luminaires LASSIE-FP7 (lassie-fp7.eu) Page 12

Light Management: Concept Color Changing Films (CCFs) Flexible & R2R compatible Organic fluorescent materials Broad spectrum High color rendering Commercial PC foil (0.5mm) High transmittance Low optical absorption Compact blue LEDs l max : 470nm / FWHM: 20nm Angular aperture: ±60 o Parameters optimized for max. efficiency o < 5mm total module thickness o Compatible with R2R integration High reflectance substrate Good adhesion / LED bonding Highly resistant to scratches Patent pending Copyright 2015 CSEM Large Area Solid State Intelligent Efficient luminaires LASSIE-FP7 (lassie-fp7.eu) Page 13

Light Management: Modelling Refractive microstructures Geometric optics (ray tracing) Diffractive nanostructures Wave optics (RCWA) RCWA ZEMAX RCWA-calc. in-coupled light ZEMAX source Profiting from ZEMAX built-in features: o CAD design (no design limitations) o Integrated number of sensors RCWA + Ray tracing MATLAB code: RCWA + Ray tracing modules Multiples in- & out-coupling gratings Light recycling by the substrate Patent pending Copyright 2015 CSEM Large Area Solid State Intelligent Efficient luminaires LASSIE-FP7 (lassie-fp7.eu) Page 14

Light In-coupling: Gratings Grating parameters optimized for Optimized grating design o o Maximum efficiency Compatibility with manufacturability limits 50% in-coupling efficiency 25% transmittance 25% reflectance (recycled by substrate) Patent pending Copyright 2015 CSEM Large Area Solid State Intelligent Efficient luminaires LASSIE-FP7 (lassie-fp7.eu) Page 15

Light In-coupling: Gratings o > 80% in-coupling efficiency for ±10 polar incident angles (all azimuthal) o LED beam pattern can be shaped using micro-optics Grating optimized for max. efficiency the peak wavelength Maximum in-coupling nearly constant and compatible with a wide range of experimental conditions Patent pending Copyright 2015 CSEM Large Area Solid State Intelligent Efficient luminaires LASSIE-FP7 (lassie-fp7.eu) Page 16

Light Out-coupling: Microstructures Total optical power: 1W WAVEGUIDE ONLY ENGINEERED 1D OUT-COUPLING MICROSTRUCTURES Irradiance (W/cm 2 ) 37 % efficiency 68 % efficiency 76% efficiency Total power 0.09W Total power Total power Total power 0.37W 0.68W 0.76W No Light recycling Specular Light recycling Diffused Light recycling Total power 0.45W Total power Total power Total power 0.043W 0.068W 0.053W Patent pending Copyright 2015 CSEM Large Area Solid State Intelligent Efficient luminaires LASSIE-FP7 (lassie-fp7.eu) Page 17

Test modules: Preliminary results (no optimization) With no optimization and specific light management Power W Lum. Flux lm Rad. Power W Efficacy lm/w CCT K CRIa CRI9 LED foil 1.257-0.5649 - LED foil + CCF 1.247 105.9 0.3489 85 3101 93 78 1.248 112.5 0.3615 90 4748 93 59 Patent pending Copyright 2015 CSEM Large Area Solid State Intelligent Efficient luminaires LASSIE-FP7 (lassie-fp7.eu) Page 18

Intelligence: Colour feed-back Intelligent luminaires require colour feed-back Accurate colour-sensing feedback Cost-effective colour multispectral sensors Targeted solutions 16 CMOS photodiodes with different filters Up to 16 spectral channels Courtesy of FhG IIS Copyright 2015 CSEM Large Area Solid State Intelligent Efficient luminaires LASSIE-FP7 (lassie-fp7.eu) Page 19

Multispectral CMOS sensor for colour feed-back Spectral filters CMOS integration Conventional CMOS photodiode Metallic nanostructures Hole arrays (period 200 400 nm) Enhanced transmission due to plasmon resonances Filter wavelength is tailored by varying the geometry CMOS photodiode with integrated metallic nanostructures as on-chip optical filters Copyright 2015 CSEM Large Area Solid State Intelligent Efficient luminaires LASSIE-FP7 (lassie-fp7.eu) Page 20

Colour filters: Metallic nanostructures Simulation Fabrication Blue filter (460 nm) Two nanostructured metal layers Peak wavelength = 460 nm Peak transmission = 55 % FWHM = 55 nm Filter set for the the multispectral sensor (example) Multispectral sensor 5 filters Range = 400 600 nm Copyright 2015 CSEM Large Area Solid State Intelligent Efficient luminaires LASSIE-FP7 (lassie-fp7.eu) Page 21

Environmental & Cost assessment Environmental & Cost assessment at early stage of design Advantages : reduce the environmental load / flexibility Limitations: new materials / processes / products, evolving development Fulfilment of environmental specifications To identify environmental requirements or limitations and identify sustainability priorities o o o Technical requirements: legal (e.g. directives on ecodesign) & best practices (e.g. ecolabelling) Recyclability and recovery goals (valorisation, reuse & recycling targets) Potentially hazardous substances (e.g. REACH regulation / RoHS directives) Environmental Life Cycle assessment (LCA) To analyse the contribution to different environmental impacts of processes, materials and energy resources used during the life cycle of the lighting module. Copyright 2015 CSEM Large Area Solid State Intelligent Efficient luminaires LASSIE-FP7 (lassie-fp7.eu) Page 22

Thank you for your attention! Acknowledgements: