National Center for Nanoelectronics, etc. Makes Progress in the Study of Molecular Spin Photovoltaic Devices

China Instrument Network Instrument R&D Recently, Sun Xiangnan, a researcher of the National Nanoscience Center of the Chinese Academy of Sciences, and Hueso, a professor of the Basque Nanoscience Center in Spain, have made important progress in the study of molecular spintronics. New molecular spins have been proposed and reported. Photovoltaic devices. The relevant research results were published online in the journal Science on August 18 and have applied for national invention patents (Application No. 5).

Molecular Spin Photovoltaic Device Schematic

Due to its rich photoelectric properties, molecular semiconductor materials are widely used in the research of molecular electronic devices such as photovoltaic cells, light emitting diodes, and field effect transistors. In addition, due to the weak spin-orbit coupling of molecular materials, the spin relaxation time can reach milliseconds, making it an attractive spin transport material. The effective integration of the rich photoelectric properties of molecular semiconductor materials with excellent spin transport properties is a new way to explore the construction of new functional molecular spintronic devices and to achieve breakthroughs in molecular spintronics research.

Molecular Spin Photovoltaic Device (MSP) is a novel device based on spin valve device structure and fullerene (C60) molecular materials. The device can realize the mutual coupling of electron spin and charge output signal under the action of external light and magnetic recombination field, thus realizing new device functions, including: magnetic field regulates the open-circuit voltage of solar cells and can be controlled at a room temperature with a specific control mode. Spin-polarized current output, magnetron AC signal output, magnetron battery switch, etc.

In the spin-valve operating mode of the MSP device, a ferromagnetic electrode (Co) is used to inject spin-polarized carriers into the C60 semiconductor layer, and another ferromagnetic electrode (NiFe) is used for spin detection, spin. Polarized carriers are transported through the C60 film. Under constant bias voltage, the output current of the device changes with the relative magnetization direction of the two ferromagnetic electrodes (ie, spin valve effect), and the percentage of output current affected by this effect is called magnetic current (MC). In addition, the MSP device can observe weak photovoltaic effect under the irradiation of white light of 7.5Mw/cm2. Under short-circuit conditions, the photocarriers in the C60 layer are driven by the built-in electric field and diffused into the two ferromagnetic electrodes to generate the output current. These carriers completely spin in a very short time after being output through the magnetic electrode. Relaxation does not produce a spin valve effect. When the device is open circuit, an applied voltage will drive the electrons from the Co electrode to the NiFe electrode for charge recombination. Because of C60's excellent spin transport properties, the composite current will be affected by the spin valve effect. As mentioned above, under the action of the optical and magnetic recombination fields, the spin correlation of the output current and the composite current of the MSP device is the key to achieving the functionality of the new spin device.

The proposed molecular spin-photovoltaic device as a new type of device has potential applications in high-sensitivity optical and magnetic composite field sensors, single-device magnetic current converters, and the like compared to conventional molecular spin valves. The operating power of the device to obtain the same magnetic current response signal is reduced to less than 1%. At the same time, the device can also be applied to the research of molecular semiconductor spin materials such as spin transport and spin photonics.

Sun Xiangnan was the first author of the article, Hueso was the author of the correspondence, and the National Nanoscience Center was the first completion unit. This work was funded by the Chinese Academy of Sciences' "First Action" 100-person plan, the National Natural Science Foundation of China, and the Ministry of Science and Technology's key R&D program.

(Original title: National Center for Nanoelectronics has made important progress in the research of molecular spin photovoltaic devices)