1. What is Quantum Efficiency?

Definition: Quantum efficiency (QE) measures how effectively a device converts incident photons into emitted photons or electrons.

Purpose: It's crucial for evaluating the performance of photodetectors, solar cells, LEDs, and other optoelectronic devices.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( QE \) — Quantum efficiency (%)
• \( N_p \) — Number of photons emitted or electrons generated
• \( N_i \) — Number of incident photons

Explanation: The ratio of output photons to input photons, expressed as a percentage, shows the device's conversion efficiency.

3. Importance of Quantum Efficiency

Details: Higher QE means better performance. Solar cells with high QE produce more electricity, and detectors with high QE are more sensitive.

4. Using the Calculator

Tips: Enter the number of emitted photons (or electrons) and incident photons. N_i must be greater than 0.

5. Frequently Asked Questions (FAQ)

Q1: What's a good quantum efficiency value?
A: Values range from 0-100%. Good devices typically have QE > 70%, with some reaching 95% or more.

Q2: What's the difference between external and internal QE?
A: External QE counts all incident photons, while internal QE only counts absorbed photons (always higher).

Q3: How is this different from energy conversion efficiency?
A: QE counts photons, while energy efficiency considers photon energy vs. output energy.

Q4: Can QE exceed 100%?
A: Normally no, but in some cases (like avalanche photodiodes) it can appear to due to electron multiplication.

Q5: How do I measure the photon counts?
A: Use calibrated photodetectors and light sources, or refer to device specifications.