External quantum efficiency (eqe)

Definition

External quantum efficiency (eqe) is a measure of the effectiveness of a light-emitting device, specifically the ratio of the number of photons emitted to the number of charge carriers (electrons and holes) that recombine to produce light. A high eqe indicates that a greater proportion of charge carriers are contributing to light emission, which is critical for the performance of devices like light-emitting diodes. Understanding eqe is essential for optimizing the design and material selection in these devices, influencing factors such as brightness and energy efficiency.

5 Must Know Facts For Your Next Test

1. Eqe is crucial for evaluating the performance and efficiency of light-emitting diodes, impacting how effectively they convert electrical energy into light.
2. Factors influencing eqe include material properties, device architecture, and external conditions such as temperature and applied voltage.
3. An ideal LED would have an eqe approaching 100%, meaning every charge carrier that recombines produces a photon.
4. High external quantum efficiency can lead to reduced energy consumption and longer lifetimes for LEDs, making them more desirable for commercial applications.
5. Improvements in eqe are often achieved through advanced materials, better thermal management, and optimizing the geometry of LED structures.

Review Questions

• How does external quantum efficiency (eqe) relate to the overall performance of light-emitting diodes?
  • External quantum efficiency (eqe) directly impacts the performance of light-emitting diodes by determining how effectively charge carriers contribute to light emission. A higher eqe indicates that more electrons and holes are successfully recombining to emit photons, leading to brighter lights with less energy wasted. This relationship makes eqe a key metric when designing LEDs to maximize their brightness and energy efficiency.
• Discuss the factors that can affect external quantum efficiency (eqe) in light-emitting diodes and their implications for device design.
  • Several factors can influence external quantum efficiency (eqe) in light-emitting diodes, including material quality, device structure, and external operating conditions like temperature. For instance, poor quality materials can lead to non-radiative recombination losses, reducing eqe. Device designs that optimize electron and hole transport pathways can enhance eqe by increasing the likelihood of successful recombination. Understanding these factors is essential for engineers when developing more efficient and longer-lasting LED products.
• Evaluate the significance of external quantum efficiency (eqe) advancements in the context of future lighting technologies.
  • Advancements in external quantum efficiency (eqe) are significant as they drive improvements in lighting technologies toward sustainability and energy savings. As eqe increases through innovations in materials and design, LEDs become more efficient, emitting more light per unit of power consumed. This efficiency not only reduces energy costs but also contributes to lower environmental impact by decreasing electricity demand. The ongoing pursuit of higher eqe is essential for developing next-generation lighting solutions that align with global efforts toward greener technology.

Related terms

Internal Quantum Efficiency (iqe): The ratio of the number of photons generated internally to the number of electron-hole pairs recombining in a device.

Light-Emitting Diode (LED): A semiconductor device that emits light when an electric current passes through it, utilizing the recombination of electrons and holes.

Recombination: The process by which an electron and a hole pair annihilate each other, resulting in the emission of a photon or other forms of energy.