How do hybrid materials increase the photovoltaic cell conversion efficiency by a factor of 1,000

With the continuous development and use of new energy sources, scientists are also thinking about how they can make full use of new energy resources and reduce some unnecessary losses during their use. As a result, a new hybrid material for solar cells came into being. Using this material can convert part of the previously wasted solar energy into electrical energy, thereby greatly improving the conversion efficiency of solar energy.

Prof. Christopher Bardeen of the University of California and his research team have found through a series of experiments that mixed molecular nanocrystals can combine two low-energy photons to produce a high-energy photon, which not only maximizes solar energy conversion efficiency, but also greatly The cost of solar power generation is reduced, which indicates that humanity has taken an important step in the field of solar cell preparation.

Photo caption: (a) When a green laser beam strikes the cadmium selenide coated organic material, it will be converted into higher-energy light; (b) When irradiated with cadmium selenide coated with other materials Light will pass straight through.

Scientists pointed out that rainbows are composed of photons of different wavelengths, and their wavelengths are different, and their emitted energy is also different. In general, the longer the wavelength of photons, the lower the energy, and this also prepares solar energy for solar energy engineers. The battery provides inspiration. The working principle of solar cells is to make photons interact with electrons and convert photon energy into electrical energy.

All solar cells have a bandgap (the difference between the lowest point of the conduction band and the highest point of the valence band, and the larger the bandgap, the lower the conductivity of the conduction band). During use, solar cells are only Photons with energy above the bandgap can be used, while photon energy below the bandgap cannot be used well. As a result, the solar cell captures less than 34% of sunlight, and if the two low-energy photons can be combined into a photon with a higher energy than the band gap, the excess energy can be trapped and the solar cell can be enhanced. The conversion efficiency. Specifically, this conversion process is: a photon will increase the energy of one of the electrons to the excited state, and another photon will appear before the electron changes back to the ground state; and then the second photon will increase the energy of the electron to A higher excited state, and when the electrons again become the ground state, it releases the energy of both through a photon with a shorter wavelength.

So how do you make photons happen? Bardeen discovered through a series of experiments that the selenium nanocrystals coated with organic rubrene and diphenylanthraquinone can convert near-infrared photons into orange-yellow light with a wavelength of 550 nanometers. Berdeen said: "The selenium nanocrystals absorb two photons and then transfer their energy to the organic components, so that the organic compounds produce a high-energy photon. Simply put, it is absorbed by the inorganic materials in the composite material. The photons are then released by organic matter.” Berdeen pointed out that by “special treatment” of infrared light, the absorption rate of solar cells to solar light is greatly improved, and the power conversion efficiency of solar cells is increased by a factor of 1,000.

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