New Research on Large-area and Flexible Near-infrared LED by NUS

Researchers at National University of Singapore (NUS) developed highly efficient, large-area and flexible near-infrared LEDs for new wearable device technologies.

A research team led by Prof TAN Zhi Kuang from the Department of Chemistry and the Solar Energy Research Institute of Singapore (SERIS), NUS has developed high-efficiency near-infrared LEDs which can cover an area of 900 mm2 using low-cost solution-processing methods. The result was published on Nature Photonics on December 2, 2019.

According to the research, the flexible near-infrared LEDs are much bigger than the sizes achieved in other reports, and open up a range of new applications. Their devices employ a novel perovskite-based semiconductor, which is a direct-bandgap semiconductor that is capable of strong light emission. By using a new device architecture, the research team is able to precisely tune the injection of electrons and holes (negative and positive charges) into the perovskite, such that a balanced number of opposite charges could meet and give rise to efficient light generation. The team also found that this improvement allowed large-area devices to be made with significantly higher reproducibility.

(A) shows uniform electroluminescence from a large-area flexible perovskite LED
(B) shows illumination with near-infrared perovskite LED on the fist, showing the imaging of subcutaneous blood vessels. (Image: Nature Photonics)

The research team noted that the hole-injection efficiency is a significant factor that affects the performance of the devices. By using an organic semiconductor with a shallower ionisation potential as part of the device structure, the hole injection and charge balance can be improved. As a result, the devices can emit light at efficiencies (external quantum efficiency of 20%) close to their theoretical limit, and additionally reduced the device-to-device performance variation, hence enabling the realization of much larger devices.

The co-author, Prof. Zhi-Kuang Tan said, “Some of the technologies that our device could enable may include covert illumination in facial recognition or augmented reality/virtual reality eye-tracking technologies. In particular, we have demonstrated that our LEDs could be suited for applications involving subcutaneous deep-tissue illumination, such as in wearable health-tracking devices.”

“These materials could also be developed to emit light in the full range of visible colours. They could therefore be applied in newer generations of flat-panel electronic displays,” he added.

Disclaimers of Warranties
1. The website does not warrant the following:
1.1 The services from the website meets your requirement;
1.2 The accuracy, completeness, or timeliness of the service;
1.3 The accuracy, reliability of conclusions drawn from using the service;
1.4 The accuracy, completeness, or timeliness, or security of any information that you download from the website
2. The services provided by the website is intended for your reference only. The website shall be not be responsible for investment decisions, damages, or other losses resulting from use of the website or the information contained therein

Proprietary Rights


You may not reproduce, modify, create derivative works from, display, perform, publish, distribute, disseminate, broadcast or circulate to any third party, any materials contained on the services without the express prior written consent of the website or its legal owner.