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2D materials combine, polarize and produce photovoltaic effect



Polarized photovoltaic characteristics

Tungsten selenide (WSe2) and black phosphorus (BP) do not exhibit polarized electronic behavior until they are combined so that their structures overlap. Image source: ©2021 Ideue, etc.

Researchers have discovered for the first time a way to obtain polarity and photovoltaic behavior from certain non-photovoltaic atomically flat (2D) materials. The key lies in the special arrangement of materials. The effect produced is different from the photovoltaic effect usually found in solar cells, and may be better than the latter.

Solar energy is considered a key technology away from fossil fuels. Researchers continue to innovate more effective methods to generate solar energy. Many innovations come from the field of materials research. Toshiya Ideue, a researcher in the Department of Applied Physics at the University of Tokyo, and his team are interested in the optoelectronic properties of 2D materials and the interface where these materials meet.

Ideue said: “Usually, the interface of multiple 2D materials exhibits different properties to individual single crystals.” “We found that when stacked in a very specific way, two specific materials that usually do not exhibit the photovoltaic effect Will show this effect.”

The two materials are tungsten selenide (WSe2 pcs) And black phosphorus (BP), both have different crystal structures. Initially, these two materials are non-polar (no preferred direction of conduction), and will not generate photocurrent under light. However, Idieah and his team found that by stacking WSe2 pcs When BP and BP are combined in the correct way, the sample exhibits polarization, and when light is projected onto the material, it generates an electric current. Even if the irradiated area is far away from the electrodes at both ends of the sample, this effect will occur. This is different from the way the ordinary photoelectric effect works.

Polarized photovoltaic characteristics

Under laser irradiation, the layered material generates electric current. Image source: ©2021 Ideue, etc.

The key to this behavior is the way of WSe2 pcs Align with BP. The crystal structure of BP has reflection or mirror symmetry on a plane, while WSe2 pcs It has three rows of mirror symmetry. When the symmetry lines of the material are aligned, the sample will acquire polarity. This layer stacking is a delicate task, but it also reveals to researchers new features and functions that cannot be predicted simply by looking at the ordinary form of the material.

Ideue said: “The biggest challenge for us will be to find a good combination of 2D materials with higher power generation efficiency, and to study the effect of changing the angle of the chimney.” “But it is very exciting to discover the unprecedented emerging properties of materials. Hope. One day, this research can improve solar panels. We hope to explore more unprecedented characteristics and functions in nanomaterials.”

The research was published in science.


Breaking the symmetry leads to a responsive organic photodetector


More information:
Van der Waals interface can produce in-plane polarization and spontaneous photovoltaic effect. science, Science.sciencemag.org/cgi/doi…1126/science.aaz9146

Provided by the University of Tokyo



Citation: 2D materials merge, polarize and produce photovoltaic effects (April 1, 2021), from April 2, 2021 from https://phys.org/news/2021-04-2d-materials-combine-polarized- photovoltaic.html search

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