Development of Ultra-Thin Quantum TV and Display Devices

Research Team of UNIST Professor Kyungduk Park and Sungkyunkwan University Professor Sohee Jeong

Illustration depicting strain control of perovskite quantum dots using tip-enhanced photoluminescence nanoscopy

[Asia Economy Reporter Kim Bong-su] A new method to control the brightness and color (wavelength) of quantum dots used in display devices like TVs has been developed. The brightness and wavelength are adjusted by pressing a single quantum dot particle with an ultra-fine probe. This is expected to aid the development of next-generation quantum dot display devices such as ultra-thin, low-power quantum dot TVs.

Ulsan National Institute of Science and Technology (UNIST) announced on the 3rd that Professor Kyungduk Park of the Department of Physics, together with Professor Sohee Jung of the Department of Energy Science at Sungkyunkwan University, succeeded in freely controlling the brightness and wavelength of light emitted from a single perovskite quantum dot particle.

They used a technology that changes the brightness and wavelength of quantum dot light by applying high pressure to perovskite quantum dots with a probe of an ‘active probe-enhanced photoluminescence nanomicroscope,’ inducing structural deformation. Notably, this technology can increase the brightness of quantum dots by more than 100,000 times, making it applicable to ultra-high luminance (brightness) displays.

Quantum dots are tiny semiconductor particles on the scale of a few nanometers (nm, 10^-9 m). They can emit light of specific colors on their own, enabling the production of thin and lightweight TV or smartphone screens without the need for backlights or color filters. However, once quantum dots are synthesized, it has been very difficult to adjust their emission properties such as brightness or color, limiting their application in device development.

The research team connected the atomic force probe of the ‘active probe-enhanced photoluminescence nanomicroscope’ to a piezoelectric device to apply pressure to perovskite quantum dots and control their emission properties. This microscope, developed earlier by the research team, has a controllable cross-sectional area of about 10 nanometers, allowing pressure (force per unit area) to be increased to the gigapascal (GPa) level. Another advantage of this technology is that when the probe is removed from the quantum dot, the mechanical deformation of the quantum dot recovers, preventing structural damage and efficiency loss.

Graduate student Hyungwoo Lee of UNIST’s Department of Physics, who led the research, explained, “We not only proved for the first time in the world that the properties of a single quantum dot can be reversibly controlled, but also proposed a solution to the efficiency degradation problem, which was a limitation in previous quantum dot emission energy control studies. This is a new study that breaks the conventional wisdom of existing quantum dot optical property control research.”

The research team was able to analyze the emission properties of quantum dots changing with mechanical deformation at a spatial resolution of about 15 nanometers, far surpassing the diffraction limit of light, while applying mechanical pressure using the ‘active probe-enhanced photoluminescence nanomicroscope.’ In particular, when the quantum dot was positioned between a gold atomic force probe and a gold thin film, they confirmed that the emission intensity increased by about 100,000 times through the Purcell effect. They also succeeded in changing the energy band gap that determines the color (wavelength) of the quantum dot.

Professor Park said, “If the wavelength-variable ultra-high luminance single perovskite quantum dot technology introduced this time is applied to next-generation displays, it will be possible to produce very thin, low-power quantum dot TVs at a much lower cost than now. Besides displays, it can also be used in the development of various ultra-small nano-optoelectronic devices,” explaining the significance of this research.

The research results were published on the 25th of last month in the international journal 'ACS Nano.' The core technology for controlling single quantum dot properties has been filed as patents in Korea and Europe (PCT).

This content was produced with the assistance of AI translation services.