High wall-plug efficiency blue III-nitride LEDs designed for low current density operation

Abstract

Commercial LEDs for solid-state lighting are often designed for operation at current densities in the droop regime (~35 A/cm) to minimize costly chip area; however, many benefits can be realized by operating at low current density (J ≈1 - 5 A/cm). Along with mitigation of droop losses and reduction of the operating voltage, low J operation of LEDs opens the design space for high light extraction efficiency (LEE). This work presents detailed ray tracing simulations of an LED design for low J operation with LEE ≈94%. The design is realized experimentally resulting in a peak wall-plug efficiency of 78.1% occurring at 3.45 A/cm and producing an output power of 7.2 mW for a 0.1 mm emitting area. At this operation point, the photon voltage V=hνq exceeds the forward voltage (V), corresponding to a Vp/V = 103%.

Intensification of Photobiocatalytic Decarboxylation of Fatty Acids for the Production of Biodiesel

“…At perfect quantum efficiency and assuming loss‐free photon generation, the maximum theoretical energy efficiency of the reaction [Δ c H 0 products ×(Δ c H 0 educts + E photons ) −1 ] would be as high as 98.1 %. Even though the actually achieved energy efficiency in this non‐optimized lab setup was 32.1 %, already 89.8 % appear possible with the AQY reached here by optimizing the setup to match state‐of‐the‐art efficiencies for the electronic parts and the inductively coupled energy transfer [26] as well as the LEDs (see the Supporting Information) [27,28] . This is remarkable considering that established processes for the synthesis of renewable fuels such as Power‐to‐Liquids reach energy efficiencies around or below 50 % [29] …”

Photochemical Upconversion Light Emitting Diode (LED): Theory of Triplet Annihilation Enhanced by a Cavity

“…The 20% wall‐plug efficiency is lower than the approximately 30% efficiency of commercial blue LEDs, or the 80% achieved in laboratory devices . In the model, the most important factor reducing the system efficiency is the red LED's efficiency.…”

“…The 20% wall-plug efficiency is lower than the approximately 30% efficiency of commercial blue LEDs, or the 80% achieved in laboratory devices. 78 In the model, the most important factor reducing the system efficiency is the red LED's efficiency. Next most important is the fundamental upper limit that photochemical upconversion cannot exceed: 50% quantum yield.…”

Smart Wide‐Bandgap Omnidirectional Reflector as an Effective Hole‐Injection Electrode for Deep‐UV Light‐Emitting Diodes

“…The EQE of 8.49% is an outstanding value achieved by the FC DUV‐LED without an additional processing for light extraction. Figure e shows the WPE as a function of the injection current, which can be calculated as where P in and V are the input electrical power and diode voltage, respectively . The reported WPEs of AlGaN‐MQW‐based DUV‐LEDs are lower than 4.5% owing to the high operation voltages originated from the contact resistances between the p‐electrodes and p‐AlGaN.…”