Design Of Micro-nano Photonic Structure And Its Response Regulation To Solar Cells

Clean and sustainable energy supply is the most important scientific and technological challenge that mankind has faced in the past decades.Solar energy can be used as an ideal solution to this problem because of its abundant reserves,clean and pollution-free characteristics.Among various utilization approaches,solar cell technology is the most outstanding,which can directly convert solar energy into electric energy current solar cells.However,it is difficult for current solar cells to achieve high efficiency and low cost at the same time,which seriously restricts its practical application.The application of light trapping technology can achieve these two objectives at the same time.The micro-nano photonic structure designed on the surface of the cell device can effectively reduce the reflection loss,increase the photons in the response layer,and extend the photons’ travel path and residence time,thus improving the photoelectric conversion efficiency.In this paper,silicon-based solar cells are taken as the research object to study the effect of different micro-nano photonic structures on the improvement of photoelectric conversion efficiency of silicon-based solar cells.Firstly,rigidly coupled wave analysis(RCWA)and finite-difference time-domain(FDTD)were used for optical simulation,the optimized design of the photon structure was carried out,and the influence of the structure on the photoelectric performance of amorphous silicon(a-Si)thin film cells was discussed.Photonic structure can provide effective diffractive scattering and gradient refractive index,break the difference of refractive index existing at the air/glass interface,make more photons enter the battery,improve the efficiency of the cell.The propagation of incident light in a photon structure is related to the shape,period and duty cycle of the structure.The optimized structure can better make the incident light diffracted and scattered,and meet the requirements of the solar cell for the wide spectrum of light capture.The simulation results show that the optimal photonic structure is P = 270 nm,f = 0.35 hemispheres,and the spectral response,external quantum efficiency and photogenerated current of the cell device based on this structure are obviously improved.The photoelectric conversion efficiency of the amorphous silicon thin film cell with absorption layer thickness of 400 nm is 8.04%,which is 5.9% higher than that of the flat cell of the same size.Secondly,a variety of micro-nano processing techniques were used to prepare three kinds of characteristic scale micro-nano photonic structures,which were imprinted on the surface of glass by ultraviolet nanoimprinting technology,and the light trapping characteristics of them were analyzed.The experimental results show that the micro/nano photonic structure can combine the advantages of light trapping with different characteristic sizes to significantly reduce the surface reflection loss and improve the haze of the device.In the wavelength range of 400-1200 nm,the transmittance of cylinder and circular cone glass with characteristic size much larger than the wavelength length is about 92.74% and 93.9%,and the haze is increased by 67.2% and 64.1%.The transmittance of the hemispherical and hemispherical pitting glass in the approximate wavelength range is about 93.5% and 94%,and the haze is relatively increased by 70.6%and 72.5%.The transmissibility of the glass with circular table and inverted table smaller than wavelength is about 93.72% and 92.55%,and the haze is increased by 56.2% and59.2%.Under the AM 1.5 solar spectrum,the photoelectric conversion efficiency of crystalline silicon solar cells based on micro/nano photonic structure were significantly improved.This paper focuses on the light trapping method of micro-nano photonic structure,which is of great significance to reduce the optical loss of the cell surface,enhance the photon absorption of the response layer and improve the conversion efficiency.