The Impact of Spectral and Spatial Exciton Distributions on Optical Emission From Thin-Film Weak-Microcavity Organic Light-Emitting Diodes

Epstein, Ariel; Tessler, Nir; Einziger, P.D.

doi:10.1109/jqe.2010.2049000

Cited by 11 publications

(38 citation statements)

References 36 publications

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“…In view of our previous work on radiation from plane-stratified media [e.g., Epstein et al, 2010aEpstein et al, , 2010b, it is worthwhile to point out clearly the novel contributions of the present paper. First, it presents a systematic comparison between radiation patterns of 2-D and 3-D statistical sources, based on an original TE/TM decomposition of the sources.…”

Section: Introductionmentioning

confidence: 87%

“…The interpretation of the various parameters is conventional and is given in great detail in Epstein et al [2010b]. All sources are assumed to be time harmonic, with time dependence of e j t ; the wave number and wave impedance of the nth layer are defined as…”

Section: Formulationmentioning

confidence: 99%

“…The observation point is denoted by ⃗ r, where for the 3-D model ⃗ r = cosx + sinŷ + zẑ, with ( , , z) being the cylindrical coordinate system, and for the 2-D model ⃗ r = t̂t + zẑ, with the transverse coordinate varying due to the different orientation of the 2-D electric ( e t = y) and magnetic ( m t = x) line sources [Epstein et al, 2010b]. In both 2-D and 3-D cases, the angle between the z axis and ⃗ r is , and the source vector is ⃗ r ′ = z ′ẑ .…”

Section: Formulationmentioning

confidence: 99%

“…Extending previous work [Sokolik, 2003;Epstein et al, 2010b], we express the transverse electromagnetic fields of the 2-D and 3-D cases by the 2-D and 3-D Green's functions,…”

Section: Green's Functionsmentioning

confidence: 99%

“…These operators act on an arbitrary function f ( ) and defined asĪf [Sokolik, 2003]. Applying the continuity, source, and radiation conditions on the 1-D Green's function, we derive recursive relations for g (z, z ′ ) in the nth layer [Epstein et al, 2010b;Chew, 1990]. As a matter of fact, the latter takes the same form for all sources discussed herein.…”

Section: Green's Functionsmentioning

confidence: 99%

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On the relevance of two‐dimensional models for radiation of statistical sources in stratified media

2014

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We present analytical closed‐form expressions for the radiation patterns of 2‐D line sources and 3‐D point dipoles embedded in a general multilayered configuration. While the former are simplified model sources, used as a preliminary analytical step to reduce derivation complexity, the latter have been shown experimentally to reproduce the electromagnetic behavior of many elementary statistical sources. By decomposing the sources to current elements generating pure transverse electric (TE) or transverse magnetic (TM) polarized radiation, we arrive at a unified format for the radiation pattern expression for all sources considered. Analyzing the common 1‐D (characteristic) Green's function, we show that the normalized TE‐polarized emission of model 2‐D electric line sources reproduces exactly the measured TE‐polarized radiation of statistical (3‐D) dipoles with random in‐plane orientation; the connection between the TM‐polarized emission of the two species is discussed, and physical interpretation is provided via the unified expression. These results specify the precise relations between the 2‐D and 3‐D models, providing intuition as well as guidelines for proper usage of simplified 2‐D results for analysis of realistic 3‐D statistical configurations.

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Section: Introductionmentioning

confidence: 87%

Section: Formulationmentioning

confidence: 99%

Section: Formulationmentioning

confidence: 99%

“…Extending previous work [Sokolik, 2003;Epstein et al, 2010b], we express the transverse electromagnetic fields of the 2-D and 3-D cases by the 2-D and 3-D Green's functions,…”

Section: Green's Functionsmentioning

confidence: 99%

Section: Green's Functionsmentioning

confidence: 99%

See 3 more Smart Citations

On the relevance of two‐dimensional models for radiation of statistical sources in stratified media

2014

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Optical design of organic light emitting diodes

Wang

Helander

et al. 2011

Journal of Applied Physics

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Out-coupling of light from organic light emitting diodes (OLEDs) is a significant challenge for the application of OLEDs in solid state lighting. Most of the light is trapped in the stratified thin film structure and the glass substrate. In this study, an optical model is developed to simulate the optical electrical field for OLEDs with a stratified structure based on the dipole source term and transfer matrix approach. The exciton distribution is also considered in the proposed model. OLEDs with weak microcavity are selected to evaluate the model. Calculation of the electroluminescence spectrum, device efficiency as well as the angular dependence is shown to have a good agreement with the experimental data. Moreover, by using the weak microcavity design, an OLED of more than 70% improved efficiency is achieved.

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Analytical estimation of emission zone mean position and width in organic light-emitting diodes from emission pattern image-source interference fringes

Epstein

Roberts²,

Tessler

et al. 2014

Journal of Applied Physics

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We present an analytical method for evaluating the first and second moments of the effective exciton spatial distribution in organic light-emitting diodes (OLED) from measured emission patterns. Specifically, the suggested algorithm estimates the emission zone mean position and width, respectively, from two distinct features of the pattern produced by interference between the emission sources and their images (induced by the reflective cathode): the angles in which interference extrema are observed, and the prominence of interference fringes. The relations between these parameters are derived rigorously for a general OLED structure, indicating that extrema angles are related to the mean position of the radiating excitons via Bragg's condition, and the spatial broadening is related to the attenuation of the image-source interference prominence due to an averaging effect. The method is applied successfully both on simulated emission patterns and on experimental data, exhibiting a very good agreement with the results obtained by numerical techniques. We investigate the method performance in detail, showing that it is capable of producing accurate estimations for a wide range of source-cathode separation distances, provided that the measured spectral interval is large enough; guidelines for achieving reliable evaluations are deduced from these results as well. As opposed to numerical fitting tools employed to perform similar tasks to date, our approximate method explicitly utilizes physical intuition and requires far less computational effort (no fitting is involved). Hence, applications that do not require highly resolved estimations, e.g., preliminary design and production-line verification, can benefit substantially from the analytical algorithm, when applicable. This introduces a novel set of efficient tools for OLED engineering, highly important in the view of the crucial role the exciton distribution plays in determining the device performance.

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The Impact of Spectral and Spatial Exciton Distributions on Optical Emission From Thin-Film Weak-Microcavity Organic Light-Emitting Diodes

Cited by 11 publications

References 36 publications

On the relevance of two‐dimensional models for radiation of statistical sources in stratified media

On the relevance of two‐dimensional models for radiation of statistical sources in stratified media

Optical design of organic light emitting diodes

Analytical estimation of emission zone mean position and width in organic light-emitting diodes from emission pattern image-source interference fringes

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