Electroluminescence (EL)

Probe Light Emission under Electrical Excitation

An optical technique that analyzes light emission under electrical excitation to reveal electronic properties of electroluminescent materials.
Time-resolved electroluminescence reveals carrier recombination dynamics under electrical excitation.
Table of contents

From Electrical Excitation to Emission and Device Insights

What is Electroluminescence (EL)?

Electroluminescence (EL) is an optical characterization technique in which light emission is generated by electrical excitation of a material or device. Under an applied bias, injected charge carriers recombine radiatively, producing photons whose spectral and spatial characteristics reveal the material’s electronic and structural properties. EL measurements are widely employed in the analysis of LEDs, solar cells, and other optoelectronic devices, offering direct insight into charge transport, recombination dynamics, and inhomogeneities under real operating conditions.

How does Electroluminescence (EL) work?

In an electroluminescence (EL) experiment, an electrical voltage or current is applied to a device, driving electrons and holes into the active material layer. When these charge carriers recombine radiatively, photons are emitted. The emitted light is collected and analyzed spectrally, temporally, or spatially to probe the material’s optoelectronic properties. EL measurements can be performed under steady-state or time-resolved conditions, enabling quantitative insights into recombination dynamics, emission efficiency, and spatial uniformity of device performance.

Electroluminescence (EL) Data & Analysis

Electroluminescence (EL) data typically comprise emission spectra, intensity maps, and time-resolved decay traces. Spectral analysis reveals key optoelectronic features such as bandgap energy, defect-related emission, and carrier recombination pathways. Spatially resolved EL imaging identifies inhomogeneities including defects, non-uniform current injection, or degradation sites. Time-resolved EL provides access to carrier lifetimes and recombination dynamics under electrical excitation. Quantitative analysis often correlates EL intensity and spectra with applied bias, current density, or temperature to extract device-relevant parameters.

PicoQuant software for Electroluminescence (EL) analysis

PicoQuant’s EasyTau 2 software enables intuitive TRPL data acquisition and decay analysis, with integrated fitting, reconvolution, and batch processing tools in a single streamlined workflow.

Electroluminescence spectra of a LED and a hybrid QD-LED under electrical excitation.

Why use Electroluminescence (EL)?

Electroluminescence directly probes light emission under realistic electrical operating conditions, making it highly relevant for device characterization. It enables the investigation of charge injection, transport, and recombination processes that cannot be accessed by optical excitation alone. EL is particularly valuable for evaluating semiconductor materials, LEDs, OLEDs, and solar cells, as well as for exploring emerging optoelectronic materials. By revealing efficiency losses, defect-induced emission, and spatial inhomogeneities, , EL supports device optimization, failure diagnostics, and the development of next-generation electroluminescent materials.

FluoTime 300 photoluminescence spectrometer for steady-state and time-resolved measurements

Instrumentation requirements for Electroluminescence (EL)

Reliable electroluminescence (EL) measurements require stable electrical excitation, sensitive optical detection, and precise synchronization between driving and acquisition systems. Essential components include low-noise voltage or current sources, spectrally calibrated detectors, and high-efficiency optical collection systems optimized for weak emission signals. For time-resolved EL, fast detectors and high-resolution timing electronics are essential to resolve recombination dynamics. Spatially resolved EL relies on imaging optics combined with scanning or camera-based detection. Additional requirements such as temperature control, background suppression, and calibration routines ensure quantitative accuracy and reproducibility.

Relevant for Your Research​

Matching Applications

Representative surface structure of a solar cell used for optical characterization studies.
Materials Science
Microscopy image of a smartphone screen captured through a 20x objective. The blue, green and red pixels selected for the measurements are indicated by boxes in the corresponding colors.
Materials Science
Time-resolved photoluminescence emission spectrum with three peaks from different layers. Adapted from Buschmann et al., J Appl Spectrosc 80, 449–457 (2013).
Materials Science

Application Examples

Spectrum of LED die and hybrid QD-LED indicated on CIE 1931 chromaticity diagram.

Time-Resolved Electroluminescence Characterization of a Quantum Dot LED

This application note demonstrates steady-state and time-resolved electroluminescence measurements of a LED and a hybrid QD-LED using the FluoTime 300 spectrometer, revealing emission spectra, chromaticity shifts, and carrier recombination dynamics under electrical excitation.

Related Methods

oft-confinement processing of a sub-micrometer polymer film using a patterned PDMS stamp, illustrating controlled structuring and morphology formation after UV cross-linking. Taken form Feng et al., ACS Nano, 10, 1, 150-158 (2016).

Photoluminescence (PL)

An optical spectroscopy technique that probes radiative recombination under optical excitation. PL reveals band structure and defect states but does not reflect charge injection or device operating conditions.

TRPL decay curves illustrating time-dependent photoluminescence and varying carrier lifetimes in advanced materials.

Time-resolved Photoluminescence (TRPL)

A time-resolved extension of PL that measures carrier recombination dynamics after pulsed excitation. TRPL provides excited-state lifetimes but lacks direct information on electrically driven recombination.

Three-dimensional representation of time-resolved emission spectra of tryptophan in saline buffer. Thirty-one wavelength-resolved decay curves were recorded and globally analyzed, revealing three characteristic lifetimes of 360 ps, 2.5 ns, and 7.4 ns.

Time-resolved Emission Spectroscopy (TRES)

A spectro-temporal method that records emission spectra as a function of time. TRES complements EL by resolving dynamic spectral shifts and recombination pathways with high temporal resolution.

In-Depth Scientific Resources

Premium Resources

Access in-depth application notes and scientific posters with detailed methods, measurement data, and real-world use cases.

Application Note: TRPL and Electroluminescence Characterization

This application note demonstrates time-resolved photoluminescence and electroluminescence measurements of quantum dot LEDs

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