Controllable Preparation And Property Investigation Of Antireflective Films For Solar Cells

Solar cell is an important way to solve energy problems and realize energy saving and carbon reduce in China,and its service life is significantly increased by covering photovoltaic glass.But it will reduce solar transmittance when protecting the solar sell.In order to increase solar transmittance,the antireflective films are often coated on the surface of photovoltaic glass to enhance the photoelectric conversion efficiency（PCE）of the corresponding solar cells.Antireflective films are generally prepared by low-cost sol-gel method,but there are still some problems,for example,low hardness and poor durability caused by weak adhesion and high porosity of the films.In order to solve this problem,the modification of organics with hydrophobic groups,compound with metal oxide and atmosphere annealing were used to prepare SiO₂-based antireflective films with controllable microstructure and respectively.The underlying relationship between microstructure and the increase of solar transmittance,films’hardness was investigated systematacially.The main results are presented as follows.（1）In order to enhance the hardness and solar transmittance increase,methyltrimethoxysilane（MTMS）was used to modify SiO₂ sol and films.The modified SiO₂ sol was prepared by sol-gel method.The effects of volume ratio（MTMS sol/SiO₂sol）and withdraw speed on the microstructure of coatings were investigated.The underlying relationship between microstructure of coating and solar transmittance increase of coating,photoelectric conversion efficiency of solar cell was discussed.The results show that with the increasing of volume ratio of MTMS sol/SiO₂ sol,the surface of films was denser,the refractive became larger and the film hardness was increased from 2B to 1H.The solar transmittance increase was increased at first and then decreased,and reached a maximum of 2.21%at the volume ratio of 1:3.The highest PCE of 17.84%was obtained at the volume ratio of 1:3.（2）ZrO₂-SiO₂ composite films with good solar transmittance increase was prepared by compositing ZrO₂ sol with SiO₂ sol which called ZrO₂-SiO₂ composite sol.The effects of n _Zr/Si and withdraw speed on the prepared composite films’solar transmittance increase were investigated.The result shows that the refractive and hardness of the films were increased with the increase of n _Zr/Si from 0.03 to 0.18.When the n _Zr/Si was 0.06,the best solar transmittance increase（2.98%）and the corresponding PCE（18.06%）were obtained.（3）SiO₂ composite films was annealed in NH₃ atmosphere to enhance films’hardness and solar transmittance increase.The TiO₂-SiO₂ composite sol and films were prepared by sol-gel method,and the influence of n _Ti/Si on composite films’solar transmittance increase was investigated.The result shows that with the increase of n _Ti/Sifrom 0 to 0.0055,the solar transmittance increase was increased at first and then decreased,the best transmittance increase of 2.37%is obtained when n _Ti/Si was 0.0034.Under this condition,the effects of NH₃ concentration and annealing temperature on solar transmittance increase and hardness of films were discussed in detail.The results show that better solar transmittance increase（3.74%）and hardness（1H）were obtained when the film was annealed at 500℃and the concentration of NH₃ was 0.1 mol/L.At the same time,the PCE of the solar cell covered by the coated film was 18.21%.And the solar transmittance increase of the prepared film was almost unchanged after sandpaper friction test and weather resistance test,indicating a good durability of the obtained film.