An OLED efficiency claim becomes useful when it identifies the measured output, electrical input, color, brightness and device boundary. A percentage, a candela-per-ampere value and a lumen-per-watt value describe different relationships. Compare like quantities under matching conditions before choosing a material, panel or display.
OLEDs generate light in thin organic-material structures between electrodes. Charge transport, emission and optical extraction all affect the output that reaches the observer. A successful small test device is an important result, but a complete display adds further layers, electronics and operating constraints.
Identify the quantity behind the headline
On a narrow screen, scroll the table horizontally. Keyboard users can focus the table region and use the arrow keys.
| Quantity | Definition or unit | Comparison requirement |
|---|---|---|
| External quantum efficiency, EQE | Emitted photons relative to injected electrons. | Device structure, collection method and operating point. |
| Current efficiency | Luminous intensity per current, commonly cd/A. | Viewing direction, emitting area and angular distribution. |
| Luminous efficacy | Luminous flux per electrical power, in lm/W. | Spectrum, optical collection and electrical boundary. |
| Radiant power efficiency | Emitted optical watts divided by electrical watts. | Collected optical output and the same input boundary. |
| Luminance | Directional brightness per projected area, in cd/m². | Viewing angle, active area and operating conditions. |
| Lifetime/maintenance | Time to a defined loss of output or another failure criterion. | Initial output, drive method, temperature and endpoint definition. |
Lumens weight the spectrum according to photopic visual sensitivity. Equal optical watts at different colors can therefore produce different lumen values. A green-emitter result cannot directly establish the efficacy of a white lighting panel or a full-color display.
Keep the color coordinates or spectrum with the number. Also record whether the result is for a bare emitter, a panel including optical layers, or a complete product at its supply input.
Follow energy through the device and its optics
Electrical losses occur as charge is injected and transported. Some excited states release energy without useful light, and some generated light remains trapped or is absorbed in the structure. The DOE-hosted OLED outcoupling presentation examines optical extraction as a separate engineering challenge.
An extraction treatment may change both the total output and its angular distribution. Measure the quantity relevant to the application: a display has viewing-angle and image requirements, while a lighting product also needs an appropriate illumination pattern. Keep the measurement geometry with any claim of improvement.
A lower drive voltage can improve electrical input for a given current, but compare the resulting light at the required operating point. Likewise, a higher peak EQE can be less useful if achieved only at a brightness far below the application’s needs.
Calculate efficacy at the correct power boundary
For a display, document the image content and brightness setting during the power measurement. A uniform test image and a typical application screen can exercise the display differently. Include control electronics and standby or operating schedules when estimating energy use.
Compare the full operating range
Efficiency can fall as current density and luminance increase, a behavior commonly called roll-off. The DOE diffuse-light-source research meeting report discusses material and device mechanisms behind this behavior. Treat that research as an explanation of the problem, not as a current specification for an unrelated panel.
- Request voltage, current and light-output data at the required luminance, not just the maximum efficiency point.
- Compare devices at matching color and temperature conditions.
- Keep active area and current density explicit when comparing different device sizes.
- Inspect output uniformity and the angular measurement method.
- Check repeatability, sample count and variation rather than selecting only a best device.
If two sources use different methods, record the mismatch instead of calculating a confident ranking from incompatible data. The next useful step may be a common measurement under the intended operating conditions.
Read the endpoint and the test conditions
A lifetime label such as L70 identifies an output-maintenance endpoint, commonly 70% of initial luminous output. It needs an initial condition, drive method, temperature and an explanation of whether the time was measured or extrapolated. Also assess color shift, dark spots and other failure criteria relevant to the product.
The DOE OLED lighting-products report page provides a useful discussion of panel operation and lifetime tradeoffs. Its product examples belong to the report’s period; consult current manufacturer data for a purchase.
Keep efficacy and lifetime requirements in the same comparison. A fictional design brief might require a particular luminance range, uniformity and maintenance endpoint after specified use. Evaluate all of those conditions together. A more efficient test point that fails the required color or service life does not satisfy that brief.
The worksheet turns a headline claim into a traceable comparison: what was measured, how it was measured, what the application needs and which evidence is still missing.
Keep a working record
Download the oled efficiency worksheet (editable text). Save a copy for each comparison or test. It includes the example assumptions, fields for source references and space for your results.