Application of radiative transport theory to light extraction from organic light emitting diodes

Abstract

One limitation on organic light emitting diode (OLED) performance is the optical extraction efficiency ηex, which is defined as the ratio of light generated within the device to light emitted into the ambient. Typical estimates for ηex, in OLEDs range between 0.17 and 0.5. We develop a simple radiative transport model that quantifies the effect of volumetric light scattering on light output in OLEDs in terms of a small set of readily measured parameters. The methodology is sufficiently general to parametrize and describe many of the light extraction schemes found in the literature. A set of model calculations is presented using typical OLED parameters; these calculations show that the introduction of light scattering sites within the otherwise transparent substrate can increase light extraction efficiencies to values between 0.55 and 1.

Synthesis and electroluminescent properties of new phenothiazyl derivatives

“…The precipitate was filtered and washed with methanol. The dark blue residue was purified by column chromatography with CHCl 3 : n-hexane (1 : 1) eluent to afford white solid (2) (23 g, 93%) 1 2.2.2. 3-Bromo-10-(4-t-butyl-phenyl)-10H-phenothiazine (3) and 3,7-dibromo-10-(4-t-butyl-phenyl)-10H-phenothiazine (6) 10-(4-t-Butyl-phenyl)-10H-phenothiazine (2) (15 g, 45 mmol), NBS (8.9 g, 50 mmol) were added to 300 ml of CHCl 3 solution.…”

“…The organic layer was dried by anhydrous MgSO 4 and filtered. The product was isolated by silicagel column chromatography using ethyl acetate : n-hexane (1 : 19) as the eluent afford yellowish green solid (4) (4 g, 60%) 1 3-Bromo-10-(4-t-butyl-phenyl)-10H-phenothiazine (3) (4 g, 9.76 mmol),10-(4-t-Butyl-phenyl)-3-(4,4,5,5-tetramethyl)-1,3,2dioxaborolan-2-yl)-10H-phenothiazine (4) (4 g, 8.75 mmol), Pd(OAc) 2 (0.68 g,2.9 mmol ) and (tris-o-tolyl) 3 P (0.9 g, 2.9 mmol) were added to DME (300 ml) solution, then the prepared K 2 CO 3 solution, which was dissolved in DME and H 2 O (1 : 1, 100 ml) solvent, was added to reaction mixture. The organic layer was concentrated and then poured into acetone to give crude solid.…”

“…Organic light-emitting diodes (OLEDs)have been the subject of intensive investigation in the past few years because of their potential application as emissive elements for flat panel displays [1,2]. Generally, layered devices consisting of charge transport and emitting layers exhibit higher performance than a single-layered device.…”

Fabrication of Photonic Crystal Structures on Flexible Organic Light-Emitting Diodes by Using Nano-Imprint and PDMS Mold

“…OLED is often to combine with nano/micro structure to enhance light extraction whose common methods are as follows: application scattering layer on the OLED surface [1], to cover an ordered microlens arrays [2], using anodic aluminum oxide (AAO) ¿lms [3], and applied photonic crystal technology [4][5][6][7]. In the technology of photonic crystal, usually use nanoimprint lithography (NIL) to fabricate.…”

Tetra-methyl substituted copper (II) phthalocyanine as a hole injection enhancer in organic light-emitting diodes

“…Over the last two decades, organic light-emitting diodes (OLEDs) have attracted increasing attention and considerable research effort because they show potential for use in flat/flexible displays, and large area solid-state lighting. [1][2][3][4][5][6] To achieve the required device performance, it is crucial to optimize charge injection and transportation. 7,8 The Schottky barrier and contact resistance present at the electrode/organic interface, 9-11 means charge injection depends significantly on this interface, and therefore interface modification is usually required to enhance power conversion efficiency and operational lifetime.…”