A new study reveals how nanoscale engineering and quantum dot technology can create ultra-thin, sunlike LEDs for healthier and more versatile lighting solutions.
Light-emitting diodes (LEDs) have come a long way since their invention in the 1920s. Initially limited to red, green, and yellow, the introduction of magnesium enabled blue LEDs, leading to the development of blended white light. Only in recent years have LEDs become the dominant source of lighting, replacing halogen and fluorescent bulbs. Yet, as our reliance on LEDs grows, so does awareness of their drawbacks—most notably, the “blue light hazard,” a risk to retinal health posed by blue wavelengths (400–500 nm). Blue light exposure has also been linked to fatigue and sleep disturbances. In response, sun-like full-spectrum white lighting is gaining popularity, offering a continuous wavelength similar to sunlight and reduced blue light hazard. This shift is driving innovation in healthy lighting, especially in formats smaller and more flexible than the traditional LED bulb.
Quantum Leap: The New Sunlike LED
A recent paper in ACS Applied Materials & Interfaces reports on an LED with sun-like, full-spectrum electroluminescence, fabricated by spin-coating a nanoscale mixture of yellow-green, red, and blue semiconductor quantum dots onto a thin glass substrate. Unlike conventional full-spectrum LEDs, which typically combine blue-emitting chips with phosphors, this quantum dot approach yields a warm white light rich in red and low in blue, potentially benefiting sleep and eye health.
Quantum dots also enable solution-based processing methods like spin-coating, printing, and stamping, making fabrication simple, cost-effective, and scalable. The researchers optimized the device’s electrically conductive layers, achieving maximum light output at just 8 volts, with about 80% of prototypes exceeding the target brightness for computer monitors.
A key material in the ultrathin LED is copper indium sulfide (CuInS₂), which the researchers chose for its environmentally friendly profile and ability to produce full-spectrum white light. The team synthesized yellow-green and red quantum dots by coating CuInS₂ cores with triple ZnS shells, using different sulfur sources to tune emission wavelengths. Blue quantum dots were made from ZnCuGaS₂ cores, also coated with ZnS shells. The resulting device emits warm white light (3000 K), with a color rendering index (CRI) of 92.4—meaning colors appear nearly true-to-life. Its electroluminescence spectrum overlaps with sunlight by 91.7% in the visible range, and the thin quantum dot layer enables a flexible, paper-like form factor.
Applications and Outlook
By leveraging quantum dots and solution-based processing, researchers are opening new avenues for thin, efficient, and eye-friendly lighting. With this technology, lighting can be seamlessly integrated into surfaces—think wallpaper that glows like the sun. Beyond healthy indoor illumination, such developments could enable wavelength-tunable sources for horticulture, adaptive displays, and even biomedical imaging.
Explore related research in ACS journals:
Glutathione-Capped CuInS2/ZnS Quantum Dots for the Determination of Pb2+ in Drinking Water and Multicolor Cellular Imaging
Syammohan V, Ramya M, Anita Mary Peter, Anjana A S, Baby Chakrapani P S, and Kailasnath Madanan*
DOI: 10.1021/acsanm.5c01959
ZnSe/ZnS Core/Shell Quantum Dots with Narrow Emission Bands for QLED Displays
Lei Chen*, Hui Jiang, Fanghai Liu, Syed Aamir Hussain, Hossein Chamkouri, Yang Song, Ping Chen, Asad Ali*, and Xianghua Wang*
DOI: 10.1021/acsaom.5c00207
Heavy Metal Free Ag2Se Quantum Dot Inks for Near to Short-Wave Infrared Detection
Shlok J. Paul, Letian Li, Zheng Li, Thomas Kywe, Ana Vataj, and Ayaskanta Sahu*
DOI: 10.1021/acsami.5c12011
Rare Earth-Doped Perovskite Quantum Dot Microspheres for Micro-LED Displays
Ting Gong, Junjun Shi, Yinggan Zhang, Wenhao Bai, Tongtong Xuan*, Tianliang Zhou, Kai Huang, and Rong-Jun Xie*
DOI: 10.1021/acsenergylett.5c02209
Microfluidic-Based Patterning of High-Resolution, Uniform Luminescent, and Low Optical Crosstalk Quantum Dot Arrays for Full-Color Micro-LED Displays
Zijun Yan, Yuhui Wang, Shibiao Liu, Wenan Guo, Guolong Chen, Xiaotong Fan, Yue Lin, Shuli Wang*, Hao-Chung Kuo, Zhong Chen, and Tingzhu Wu*
DOI: 10.1021/acsphotonics.5c01016
