Design And Preparation Of Antireflective Films Based On Hollow SiO₂@TiO₂ Nanocomposites And Gradient Refractive Index Structures

In practical applications,there are often challenges such as low transmittance and difficulty in surface cleaning of photovoltaic glass.To address these issues,a common approach is to utilize nanomaterials with low refractive index to fabricate multifunctional antireflective films,which not only enhance light absorption but also improve surface cleanliness.However,a single nanomaterial alone cannot meet the aforementioned requirements.The growing demands can be fulfilled by combining the characteristics of different nanomaterials.In this study,simulation software and improved nanoparticle synthesis were employed to introduce a gradient refractive index structure.By optimizing the sol-gel process,a broadband antireflection thin film based on hollow SiO₂@TiO₂ nanomaterials was prepared.The detailed research is as follows:（1）By adjusting the volume ratio and pH value,a tunable refractive index solid composite SiO₂ sol was prepared by mixing acid-catalyzed SiO₂ with alkali-catalyzed SiO₂.Based on Essential Macleod simulations,a five-layer gradient refractive index broadband antireflective film was constructed.Various characterization methods were systematically employed to study the film morphology and structural features.Glass substrates coated with this film exhibited an average transmittance of 97.57%（380-1800 nm）.Furthermore,during 120 hours of thermal cycling and 300 abrasion tests,the average transmittance(T_ave)only decreased by 2.35%and 1.78%,respectively,demonstrating good reliability.Application testing of the fabricated film showed a 4.83%enhancement in the short-circuit current density(J_sc)of the modules.（2）The synthesis of SiO₂/TiO₂ was optimized,along with the sol-gel volume ratio,to fabricate TiO₂-coated solid SiO₂（SiO₂@TiO₂）nanoparticles,and the optimal volume ratio was determined.Using the modifier TX-100,a three-layer gradient refractive index broadband antireflective film was designed,and comprehensive characterization was conducted using multiple devices.The glass substrates coated with this film exhibited a higher average transmittance（increased by 8.93%）compared to uncoated substrates.The film displayed excellent photocatalytic and self-cleaning properties,and its reliability was verified through wet-heat and thermal cycling experiments.In application tests,the coated modules showed a 7.60%increase in short-circuit current density(J_sc)compared to the uncoated ones.（3）The synthesis of TiO₂-coated hollow SiO₂（HSNs@T）nanoparticles was improved by refining the nanoparticle structure,adjusting the synthesis ratio and volume ratio.The optimal volume ratio was determined through various testing methods.The use of the modifier MTES improved the film’s refractive index tunability and hydrophobicity.Based on simulation software design,a three-layer broadband antireflective film with a gradient refractive index structure was fabricated,and comprehensive characterization was performed.Glass substrates coated with this film exhibited high transmittance while demonstrating superior self-cleaning ability and reliability compared to SiO₂@TiO₂ coatings.The short-circuit current density(J_sc)of solar cells coated with the film showed an improvement of 9.03%compared to uncoated cells.These results provide strong support for the large-scale application of composite films in photovoltaic modules.