Performance Research Of Silicon/Gallium Arsenide Solar Cells Under Femtosecond High Power Laser Illumination

Abstract:Femtosecond laser is a new kind of ultra-short-pulsed laser, which has the shortest pulse (10to15seconds) that we human beings can obtain in laboratory now. In this reseach, we study the damage effect and concentrating effect of silicon and gallium arsenide (GaAs) solar cells under the femtosecond laser illumination, and make the preparation of the MoS2sodium thin film to improve the damage threshold and conversion efficiency of the solar cells under the femtosecond laser.A femtosecond laser with ultrashort pulse (≤35fs) is firstly applied to study damage threshold of a monocrystalline silicon solar cell. Compared with a continuous-wave laser of the same central wavelength, a femtosecond laser pulse is found to have a slightly higher damage threshold. The result shows that the femtosecond laser is more suitable for the transmission of energy. Unlike nanosecond or picosecond lasers, the femtosecond laser’s heating pulse time equals to or is shorter than the electron-phonon coupling time, so the thermal non-equilibrium effect becomes obvious, and the thermal conduction phenomenon no longer meets the law of Fourier. In the damage threshold experiments, the beam shaping technique is applied for the femtosecond laser to generate uniform intensity distribution, which can effectively reduce experimental deviation caused by too intensive intensity of the center of the Gaussian beam.In this research, we also study the damage threshold and conversion efficiency of the GaAs solar cells under the femtosecond laser (≤35fs) illumination. The experimental result shows that, as the incident laser power increases, the conversion efficiency increases more significantly under the illumination of a femtosecond pulsed laser, compared to the case of a continuous wave laser of the same wavelength. It shows that the femtosecond pulsed laser is more propitious to transmission. It is mainly because the femtosecond pulsed laser has higher light intensity, which can trigger higher conversion efficiency in GaAs solar cells. In order to improve the damage threshold and conversion efficiency of gallium arsenide solar cells under the illumination of a femtosecond laser, we adopt respectively N, N-Dimethylformamide(DMF) and tetrahydrofuran (THF) as solvents to fabricate MoS2suspension solutions by using the discrete method, and then make solutions on the GaAs solar cell coatings. The experiment shows that the MoS2sodium thin film in the visible waveband (532nm) can increase light transmittance under a small light intensity, which indicates the improvement of the photoelectric conversion efficiency, and can decrease light transmittance under a high light intensity, which indicates the improvement of the damage threshold of the solar cells.In summary, compared with a continuous-wave laser, and nanosecond and picosecond pulsed lasers, the semiconductor solar cells have higher damage threshold and conversion efficiency under the illumination of a femtosecond laser. So the femtosecond laser is more suitable for wireless high-power energy transmission. The MoS2sodium thin film can also improve the damage threshold and conversion efficiency of the solar cells.