Can graphene's "fold" improve its light absorption?

Researchers at the University of Illinois at Urbana-Champaign have demonstrated that changing the stress on the surface of graphene, creating a "fold" structure on the surface and increasing the surface density can improve the absorbability of graphene, which is of great significance for the application of graphene in the field of optoelectronics. Of course, this research method is not only limited to graphene, but also applicable to other emerging two-dimensional materials.

The urbana-champaign, researchers at the university of Illinois urban has confirmed a new research method, by changing the thickness of the atomic two-dimensional materials such as graphene on the surface of the mechanical stress, can change the optical absorption and tensile properties. Combined with the flexible light emitting diode, this research method can promote new wear-resisting technology and the comprehensive development of biomedical optical sensing technology.

Mechanical science and engineering at the university of Illinois, an assistant professor in the college SungWooNam explained: "improve the graphene low optical absorption in the visible light range, is the application of graphene in the field of photoelectric sensor is an important precondition, this is the first fully with adjustable based strain photosensitivity and wavelength selectivity of graphene tensile photoelectric detector."

Graphene is a kind of atomic layer thickness, with hexagonal bonded carbon atoms. Graphene due to its wide absorbent, high carrier mobility and mechanical flexibility, and are widely used in the research of optoelectronic detector. However, graphene has low light absorption rate, so at present in order to improve the light absorption, graphene photo detector research mainly concentrated in the hybrid system. However, this kind of hybrid system needs a complex integration process, and the interface between different materials, reduce the mobility of charge carriers.

Another option is to increase the light absorption and stretch ability of graphene. According to Nam described above, the key is to 2 d material 3 d 'fold structure, increase the quality of graphene unit area, also known as surface density. Has high surface density, and the per unit area of 3 d surface has high optical absorption, thereby improving the photosensitivity of graphene.

By strain adjusting density, height and fold structure of graphene, wrinkling in the process of periodic stretch and release is completely reversible. The fold method for improving the light absorption of graphene provides a new way, make the creation of the monolayer graphene high sensitive detector is possible.

Pilgyu Kang, a Nam team members said: "through the three-dimensional structure of the fold, we obtain the absorbance of sex is not only an order of magnitude, but increased by about 400%.The strain sensitivity adjustable under 200% of the strain adjusting, can make the 100% sensitivity of change. Through the combination of photonic crystals with tensile graphene photoelectric detector, we presents a unique adjustable wavelength selectivity of strain."

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