Calculator inputs
The responsive grid below uses three columns on large screens, two on smaller screens, and one on mobile.
Example data table
These example rows help you verify the calculator workflow before entering your own chemistry device measurements.
| Sample | Current (mA) | Optical power (mW) | Wavelength (nm) | Voltage (V) | EQE (%) |
|---|---|---|---|---|---|
| Blue emitter A | 18.0000 | 4.5000 | 470.0000 | 3.4000 | 9.4770 |
| Green emitter B | 12.0000 | 2.8000 | 520.0000 | 3.1000 | 9.7862 |
| Red emitter C | 9.0000 | 1.9000 | 630.0000 | 2.7000 | 10.7272 |
Formula used
Core EQE equation
EQE (%) = [(P × λ × q) / (I × h × c)] × 100
- P = optical power in watts
- λ = peak wavelength in meters
- I = current in amperes
- q = elementary charge
- h = Planck constant
- c = speed of light
Derived calculations
Photon energy (J) = h × c / λ
Emitted photons/s = optical power / photon energy
Injected electrons/s = current / q
Wall-plug efficiency (%) = optical power / electrical power × 100, when voltage is provided.
How to use this calculator
- Enter measured optical power and choose the matching power unit.
- Enter device current and the wavelength representing peak emission.
- Optionally add active area, voltage, temperature, and experiment notes.
- Press Calculate EQE to place the result summary above the form.
- Review the graph, result table, and export files for reporting.
Frequently asked questions
1) What does external quantum efficiency measure?
External quantum efficiency measures how many photons leave the device for each injected electron. It focuses on emitted photons, not just internally generated ones, so it reflects overall extraction performance.
2) Why does wavelength affect EQE?
Wavelength changes photon energy. Shorter wavelengths carry more energy per photon, so the same optical power corresponds to fewer photons. That directly changes the emitted-photon count used in EQE.
3) Should I use radiant power or luminous power?
Use radiant optical power, not luminous power. EQE is based on physical photon emission, while luminous values are weighted by human eye sensitivity and can distort the calculation.
4) Can EQE be greater than 100%?
A result above 100% usually signals a unit error, incorrect optical calibration, wrong wavelength entry, or a mismatch between measured total optical power and the modeled emission assumptions.
5) What is the difference between EQE and internal quantum efficiency?
Internal quantum efficiency describes photons generated inside the device. EQE is lower or equal because it also includes optical losses, extraction losses, and other pathways preventing photons from leaving.
6) Why add active area to the form?
Active area helps calculate current density. Researchers often compare devices at matched current density rather than raw current because device size strongly influences measured performance trends.
7) Why add voltage if EQE does not require it?
Voltage is optional and supports wall-plug efficiency. That extra metric compares optical power with electrical input power, giving broader insight into chemistry device energy performance.
8) Can I use an average wavelength for broad spectra?
Yes, but it becomes an approximation. Broad or multi-peak spectra are better handled with spectrally resolved measurements, because a single wavelength can slightly shift photon-energy and EQE estimates.