Thermodynamics of Light Extraction from Luminescent Materials
Open Access
- 27 July 2017
- journal article
- research article
- Published by The Electrochemical Society in ECS Journal of Solid State Science and Technology
- Vol. 7 (1), R3211-R3226
- https://doi.org/10.1149/2.0271801jss
Abstract
Light extraction from luminescent materials, where luminescence generated in a high refractive index medium must be coupled to a lower index medium, is a complex problem with significant ramifications for efficient LED and phosphor converted LED lighting. We derive thermodynamic arguments which show that light transmission for incident Lambertian light through arbitrary structured or non-structured surfaces is always limited by the ratio of incident to output étendues. Numerical simulations of various strongly scattering surfaces in the wave-optic regime are made to confirm the surface extraction results. The results are also extended to arbitrary angular radiance distributions of incident light as in Lenef, et al. [Opt. Lett., 39, 3058 (2014)], but also generalized to cases of restricted angular output emission. Furthermore, we show how cavity effects and scattering are both needed to overcome the thermodynamic surface extraction limits. Examples of both surface scattering and a converted LED with volume scattering are given. Finally, a derivation of the Lambertian light transmission theorem is developed from scalar wave-optics to highlight the physics of the thermodynamic result and to provide limits of applicability of the surface extraction limit.Keywords
This publication has 25 references indexed in Scilit:
- Enhancement of Yellow Light Extraction Efficiency of Y3Al5O12:Ce3+Ceramic Converters Using a 2-D TiO2Hexagonal-Lattice Nanocylinder Photonic Crystal LayerIEEE Photonics Journal, 2016
- On Choosing Phosphors for Near-UV and Blue LEDs for White LightECS Journal of Solid State Science and Technology, 2015
- Extracting light out of LEDsAdvanced Optical Technologies, 2013
- High-performance GaN-based light-emitting diodes on patterned sapphire substrate with a novel hybrid Ag mirror and atomic layer deposition-TiO2/Al2O3 distributed Bragg reflector backside reflectorOptical Engineering, 2013
- 2D SiN_x photonic crystal coated Y_3Al_5O_12:Ce^3+ ceramic plate phosphor for high-power white light-emitting diodesOptics Express, 2011
- White light emitting diodes with super-high luminous efficacyJournal of Physics D: Applied Physics, 2010
- Design of superperiodic photonic-crystal light-emitting plates with highly directive luminance characteristicsJournal of the Optical Society of America B, 2009
- Directional light extraction from thin-film resonant cavity light-emitting diodes with a photonic crystalApplied Physics Letters, 2008
- Refractive index and birefringence of In
x
Ga
1–
x
N films grown by MOCVDphysica status solidi (c), 2005
- High brightness AlGaInP light-emitting diodesIEEE Journal of Selected Topics in Quantum Electronics, 2002