Tsinghua will adjust or study the wavelength components, or change the lighting properties.

Tsinghua University news network recently, the research group of Professor Tian Ling, Tsinghua University's Microelectronics Institute, published online entitled "flexible full graphene based field emission light emitting devices with adjustable spectrum" on Nature Communications ("A spectrally tunable all-graphene-based flexible field-effect light"). For the first time, the research papers published in -emitting device show that light emitting diodes can be controlled by voltage. Unlike the traditional fixed wavelength LED, the luminous wavelength of the new device can be continuously adjusted between 750nm and 450nm, breaking through the way of color synthesis of existing display devices, and is expected to have a revolutionary impact on contemporary display, lighting and communication technology. Wang Xiaomu, a postdoctoral fellow at Yale University and Tian He, a doctoral student in the Department of micro electronics, Tsinghua University, are the co authors of the article.

Spectrogram of luminous wavelength controlled by grid voltage

Up to now, all the LED devices have been determined by luminescent materials. For the existing LED, once the device is prepared, its luminous wavelength is fixed. Traditional display or lighting technology can achieve color representation or white light synthesis by adjusting the luminance of several fixed colors (typical devices using red, green and blue three primary colors). The wavelength / color tunable LED, which is first reported in the paper, can also achieve excellent color fidelity while reducing the number of light-emitting units in display devices significantly, thereby greatly optimizing the driving circuit and reducing power consumption. This achievement has far-reaching significance in related fields. "This work is expected to expand new research directions in the field of light-emitting devices" and "this work is exciting and influential," said the reviewer of the paper. 　

Mechanism diagram of luminous wavelength controlled by grid voltage

Graphene materials, which have unique physical properties, are widely used in controlled photonic / optoelectronic devices. However, because of its high zero band gap and high non luminescent recombination rate, graphene based light-emitting devices are a difficult problem and a long-term blank area in academia. Professor Ren Tian Ling's innovative research group has obtained semi reduced srGO materials at the interface between graphene oxide and reduced graphene by laser direct writing technology. The material has high conductivity of graphene and wide band gap characteristics of graphene oxide. By constructing the in plane gate structure, the voltage applied to the gate can modulate the Fermi level of srGO, so as to regulate the central wavelength of the LED luminescence in real time. The LED also has the characteristics of high brightness and flexibility, and is an ideal component for modern LED display, lighting and communication technology.

In recent years, Ren Tian Ling has devoted himself to the research of graphene and other two-dimensional electronic devices, especially focusing on new devices that break through traditional device limitations, laying the foundation for the new generation of micro nano electronic device technology, and have achieved many innovative results in new graphene based memory, acoustic devices and sensor parts, such as flexibility. Transparent graphene headphones and low power graphene resistive memories. The research results were supported by the National Natural Science Foundation of China.