The Research On Irregular Nano Wire Array Solar Cells

The semiconductor nanowire array has an extremely low filling ratio and excellent anti-reflection and trapping characteristics,and has an important application prospect in a low-cost,high-efficiency solar cell.At present,nanowire solar cells generally adopt a regular nanowire array with uniform diameter,and the light absorption performance is not optimal,and the manufacturing cost and process complexity are increased.In this paper,a multi-diameter irregular GaAs nanowire array solar cell structure is proposed.The theoretical simulation and preliminary experimental exploration of the system are carried out.The main innovations obtained are as follows:1.The spectral absorption and photoelectric conversion characteristics of single-diameter regular GaAs nanowire array solar cells were studied by FDTD Solutions and Sentaurus TCAD,respectively.The results show that the light absorption of the nanowire array has a strong diameter dependence,and the absorption peak shifts red with the increase of the diameter,and the absorption of the band other than the absorption peak is significantly weakened.The device performance was optimized in the range of 220-400 nm nanowire diameter.When the nanowire height was 2 ?m,the DP ratio was 0.5,and the diameter was 310 nm,the single-diameter GaAs nanowire array solar cell achieved the highest conversion efficiency of 16.1%.2.A multi-diameter irregular nano wire array solar cell structure is proposed,which utilizes the overlap of absorption peaks of different diameter nanowires to make up for the absorption defects of a single diameter regular nanowire array,and achieve flat and efficient absorption in a wide spectral range.In multi-diameter irregular nanowire arrays,the nanowires large diameter mainly enhance the long-wavelength absorption,while small-diameter nanowires can compensate for absorption degradation of large-diameter nanowires at short wavelengths,ensuring overall absorption efficiency.In the simulation,an irregular GaAs nanowire array with 4 diameters and 16 diameters was designed,which respectively obey the random distribution and the Gaussian distribution.The simulation results show that the optimal conversion efficiencies of 4 and 16 diameter GaAs nanowire array solar cells are 16.6%and 17%,respectively,which are significantly higher than single diameter GaAs nano wire arrays.3.The diameter distribution of GaAs nanowires is revealed by counting the size of the alloy catalytic particles.The gold film deposited on the GaAs substrate was annealed at different temperatures for different time,and then Au-Ga alloy particles were formed as catalysts for GaAs nanowire growth.The size of the alloy catalyst particles was statistically analyzed by scanning electron microscopy.The results show that the alloy particles have a diameter span of several hundred nanometers and are subject to a Gaussian distribution.As the annealing time increases,the density of the alloy particles becomes smaller,the diameter distribution range becomes larger,and the diameter mean decreases.The above series of research and comparison based on ?-?semiconductor rules and irregular nanowire array solar cells have important guiding significance for further optimizing the preparation process of new generation solar cells,reducing the fabrication cost and improving the photoelectric conversion efficiency.