Highly Efficient Light-Emitting Diodes with Microcavities

Abstract

One-dimensional microcavities are optical resonators with coplanar reflectors separated by a distance on the order of the optical wavelength. Such structures quantize the energy of photons propagating along the optical axis of the cavity and thereby strongly modify the spontaneous emission properties of a photon-emitting medium inside a microcavity. This report concerns semiconductor light-emitting diodes with the photon-emitting active region of the light-emitting diodes placed inside a microcavity. These devices are shown to have strongly modified emission properties including experimental emission efficiencies that are higher by more than a factor of 5 and theoretical emission efficiencies that are higher by more than a factor of 10 than the emission efficiencies in conventional light-emitting diodes.

Eliminating Micro‐Cavity Effects in White Top‐Emitting OLEDs by Ultra‐Thin Metallic Top Electrodes

“…Top-emitting OLEDs have so far been mainly considered for display applications, for which they are particularly attractive due to a larger color gamut and higher effi ciency compared to bottom-emitting OLEDs. [3][4][5] While monochrome top-emitting OLEDs benefi t from the micro-cavity effects [ 6,7 ] introduced by the refl ective metal electrodes, high quality white emission is diffi cult to achieve, which has so far largely excluded them from use in general lighting. Spectral narrowing and a pronounced angular dependence of the emission characteristics result in reduced effi ciency and color quality for white top-emitting OLEDs, compared to their bottom-emitting counterparts.…”

Inorganic Semiconductors for Light‐emitting Diodes

“…1.15(b), (c), and (d), respectively. The resonant-cavity light-emitting diode (RCLED) has a light-emitting region inside an optical cavity [41,42]. The optical cavity has a thickness of typically one-half or one times the wavelength of light, i. e. a fraction of a micrometer for devices emitting in the visible or in the infrared.…”

Measurement of spontaneous emission from a two-dimensional photonic band gap defined microcavity at near-infrared wavelengths

“…One dimensional photonic structures have been used successfully in light emitting diodes ͑LEDs͒ to enhance efficiency and to enhance spontaneous emission. 3 Recently, two-dimensional ͑2D͒ structures have attracted a great deal of attention [4][5][6] due to the simpler geometry, in terms of both fabrication complexity and device design as compared to three-dimensional structures. Such structures have been considered as a means of controlling in-plane spontaneous emission, a significant loss mechanism in vertical-emitting structures.…”