| The shortage of traditional energy and the environmental pollution caused by it are the important factors that restrict the development of today’s society,and it is an important task for modern people to find various new and sustainable alternative energy sources.Among them,solar energy has attracted much attention because of its environmental friendliness,abundant resources and wide distribution.However,the effective utilization of this energy depends on the design of solar cells with high efficiency and low cost.AZO(Zn O:Al)transparent conductive film is one of the important electrode materials,and its transmission and scattering of incident photons directly affect the spectral response characteristics of solar cells.The design of micro-nano texture on the surface of AZO film is of great significance to improve the final photoelectric conversion efficiency of solar cells.In this paper,the effects of pyramid,crater and crater/pyramid micro-nano texture on the photoelectric properties of AZO thin films were studied by optical simulation and experimental characterization system,and the spectral response of the thin films was enhanced through the control of composite texture,thus improving the photoelectric conversion efficiency of the battery.In the aspect of simulation,a three-dimensional electromagnetic simulation model is constructed,and the spectral characteristics of different morphologies and the response efficiency of corresponding batteries are studied by using strict coupled wave analysis(RCWA)and finite difference time domain(FDTD)methods.Numerical results show that nano-scale pyramid structure has good scattering ability for short-wave photons with wavelength less than 500 nm,while micro-scale crater structure shows obvious diffraction characteristics in the middle and long wavelength bands.The combination of the two structures can achieve wide-band photon capture,and the corresponding battery efficiency is significantly improved.When the characteristic sizes of crater and pyramid are 2.5 μm and 80 nm,the spectral response of the battery is optimal,and the calculated weighted average transmittance and haze are 89.26% and 42.36%,respectively.The conversion efficiency of a-Si thin film battery constructed by this method is 9.58%,which is 2.13% higher than that of unstructured battery of the same size.In the experiment,firstly,a flat and compact AZO film was prepared on glass substrate by magnetron sputtering,and then micro-nano structure was formed on the film surface by chemical wet etching.The experimental results show that after etching with0.5% dilute hydrochloric acid for 30 s,uniform and randomly distributed volcanic crater structures appear on the film surface,and the characteristic size is about 2 μm.After etching with 1% hydrofluoric acid for 60 s,a dense and randomly distributed pyramid structure appears on the surface of the film,with a characteristic size of about 100 nm.Etched by two acids step by step,AZO surface presents volcanic crater/pyramid composite texture,and its characteristic size is consistent with that of single acid etching.The weighted average transmittance of planar AZO is 82.0%,and the transmittance after etching with hydrochloric acid,hydrofluoric acid and two-step method is 84.4%,82.6%and 85.0%,respectively.Compared with planar AZO,micro-and nano-texture significantly enhanced the transmittance of the film,and micro-and nano-composite volcanic crater/pyramid structure had the highest transmittance. |
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