New Technique Could Pave the Way for Simple Colour Tuning of LED Bulbs

April 29, 2019

International collaboration demonstrates the possibility of tuning the colour of a GaN LED by changing the time sequence at which the operation current is provided to the device

A new technique — the result of an international collaboration of scientists from Lehigh University, West Chester University, Osaka University and the University of Amsterdam — could pave the way for monolithic integration for simple colour tuning of a light bulb, according to Volkmar Dierolf, Distinguished Professor and Chair of Lehigh’s Department of Physics who worked on the project. 

“This work could make it possible to tune between bright white and more comfortable warmer colours in commercial LEDs,” says Dierolf.

The team demonstrated the possibility of colour tuning Gallium Nitride (GaN)-based GaN LEDs simply by changing the time sequence at which the operation current is provided to the device. Light-emitting diodes or LEDs are semiconductor devices that emit light when an electric current is passed through it. Notably, the technique is compatible with current LEDs that are at the core of commercial solid state LED lighting. 

The work is described in an article published online in ACS Photonics, “Color-Tunablility in GaN LEDs Based on Atomic Emission Manipulation under Current Injection” (pubs.acs.org/doi/10.1021/acsphotonics.8b01461). In today’s active LED displays, different colours are produced by three to four individual LEDs that are placed close to each other and create the different fundamental colours needed to produce the full colour spectrum. 

“We demonstrate that this can be achieved by a single LED,” says Dierolf. “We show that is possible to attain red, green and blue emissions originating from just one GaN LED-structure that uses doping with a single type of rare earth ion, Europium (Eu). Using intentional co-doping and energy-transfer engineering, we show that all three primary colours can emit due to emission originating from two different excited states of the same Eu3+ ion (~620 nm and ~545nm) mixed with near band edge emission from GaN centred at ~430nm. The intensity ratios of these transitions can be controlled by choosing the current injection conditions such as injection current density and duty cycle under pulsed current injection.”

In other words, the team achieved colour-tunability in a single GaN-based LED through the manipulation of the emission properties of an atomic-type dopant. 

Mitchell pointed out that “the main idea of this work — the simultaneous active exploitation of multiple excited states of the same dopant — is not limited to the GaN:Eu system, but is more general. The presented results could open up a whole new field of tunable emission of colours from a single dopant in semiconductors, which can be reached by simple injection current tuning.”

According to Dierolf, this research may benefit those who are looking for more comfortable “warmer” white light from LEDs. 

“It could pave the way for monolithic integration for simple colour tuning of a light bulb,” adds Dierolf. “It would also be beneficial for micro-LED displays, since it allows for higher density of pixels.” 

The materials used in previous research on colour tunable LEDs did not allow for easy integration with current LED technology, he adds. This work is compatible with current GaN-based LEDs that are at the core of commercial solid state LED lighting.

Related Articles


Changing Scene

  • LEDVANCE Expands Ontario Presence with New Specification Agent

    LEDVANCE Expands Ontario Presence with New Specification Agent

    LEDVANCE is pleased to announce the appointment of Sterling Architectural Products Ltd. (Sterling Lights) as their new specification agent in Ontario. This partnership strengthens LEDVANCE’s presence in the region and reinforces their commitment to serving the professional lighting design and specification community with innovative, reliable lighting solutions. With decades of experience and a service-driven mindset,… Read More…

  • May 29, 2025 - Eureka Wins Three 2025 Red Dot Awards for Product Design

    Eureka Wins Three 2025 Red Dot Awards for Product Design

    Eureka is pleased to announce that its Velia, Cirra, and Junction luminaires have each received a 2025 Red Dot Design Award for Product Design. It is the 11th consecutive year that Eureka products have been honored with this prestigious award, which is a testament to the company’s consistency and relentless drive to design exceptional luminaires.… Read More…


Design

  • Mac’s II Agencies: Case Study – Tesoro, Vancouver, BC

    Mac’s II Agencies: Case Study – Tesoro, Vancouver, BC

    At the crest of False Creek, Tesoro stands as a contemporary interpretation of classic luxury, offering 92 exclusive waterfront homes in the heart of Vancouver. Developed by Concert Properties, this 17-story residential tower embraces a distinctly modern character, harmonizing sleek design with timeless sophistication. The vision for Tesoro extended beyond its architectural presence—it was about… Read More…

  • LightForm: Estiluz – Versatile Solutions for Sophisticated Spaces

    LightForm: Estiluz – Versatile Solutions for Sophisticated Spaces

    For anyone seeking high-performance lighting that blends elegance with engineering, Estiluz offers an exceptional range of solutions. This Spanish brand, family-owned since 1969, creates lighting that balances form, function, and flexibility, making it ideal for both bold architectural statements and subtle design enhancements. At LightForm, they are proud to be the exclusive Canadian distributor of… Read More…


New Products

  • Cyclone Lighting Introduces New Taji Luminaire

    Cyclone Lighting Introduces New Taji Luminaire

    Cyclone Lighting is excited to announce the release of its new Taji luminaire. Taji’s captivating design features high-performance optics and enhances a variety of aesthetics. Taji’s distinctive, stylish silhouette and slender lines are a refreshing departure from the ubiquitous dome luminaire. The unique flared form maintains a slender, minimalist feel yet provides high-performance optics. The… Read More…

  • Leviton Releases New Decora Smart Wi-Fi 0-10V Dimmer for Home & Small Business Lighting Control

    Leviton Releases New Decora Smart Wi-Fi 0-10V Dimmer for Home & Small Business Lighting Control

    Leviton has announced the launch of the Decora Smart Wi-Fi 0-10V Dimmer (D2710), expanding its comprehensive Wi-Fi lighting and load control solutions that work with the My Leviton app. As the first Matter-compatible 0-10V smart dimmer, the new 120V/277V device makes it easy to add 0-10V dimming to smart platforms such as Apple Home, Amazon… Read More…