| Summary: | 碩士 === 國立中山大學 === 機械與機電工程學系研究所 === 98 === Recently, the skills to reduce the solar cell reflectance at oblique incidence to enhance the overall efficiency of solar cells attracted much attention. the relationships between geometric structures, aspect ratios (depth over width) and sizes of the anti-reflective film (AR film) with the angles of incidence by using an optical simulation software "TracePro ". Simulation results showed that the anti-reflection effect produced by the trench structure is much lower than that of the plane structure. Structure of the higher aspect ratio and smaller size can also be effective in improving anti-reflection.
PDMS was chosen as the material to construct an anti-reflective layer. Then, the study used optic lithography techniques to produce square-column structures with aspect ratios of 0.5 and 2 and also four pyramid structures of sizes 20,40,60,80 microns. Using a solar simulator we measured and calculated efficiency in generation of power with respect to different angles of incidence. At angle of incidence at 60 degrees, structure with aspect ratio of 2 obtained 14.7% higher efficiency in power generation than that of structure with ratio of 0.5. Decrease in size also enhanced efficiency. Also at 60 degrees of incidence, pyramid structure of 20um obtained over 19.6% of generating capacity than that of pyramid structure of 80um .
At last, etching of PDMS surface was completed using carbon tetra fluoride (CF4) plasma. The PDMS surface thus became random nano-structure. Using Electron microscopy, the desired feature was discovered to become a micron-level structure if the processing time of plasma etching exceeds 4 hours. Two types of structures were produced by CF4 plasma etching, that by processing time of 2 hours and 4 hours on the AR film, respectively. At a 60-degree angle of incidence, AR film by 4 hours of etching obtained 18.8% greater generating capacity than that of AR film by 2 hours of etching.
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