TAILIEUCHUNG - Solar Cells Silicon Wafer Based Technologies Part 2

Tham khảo tài liệu 'solar cells silicon wafer based technologies part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 16 Solar Cells - Silicon Wafer-Based Technologies interference reflectance or constructive interference transmittance the distance between mirrors is d Ả 4. Fig. 14. Bragg reflection effect of mirror stacks structure with distance d Ả 2. Furthermore if there is only a single thin-film structure as shown on Figure-15 then by using Fresnel equation and assumed that the design is for a normal incidence then on each interface will occurs reflectance which is written as 2 r níùr nAR and r2 nAR nSl nair nAR nAR nSi 20 where ri is interface between air and antireflection coating AR and r2 is interface between AR and silicon. Fig. 15. Bragg reflection effect of mirror stacks structure with distance d Ả 4. Solar Cell 17 2 21 When the AR coating thickness is designed to be War d Aq 4 and in normal incidence then the total or overall reflectance is minimum and can be written as follows 21 p f kAr - nairnSi Rmin I 2 I nAR nairnSi Furthermore it can be obtained zero reflectance if n2AR - nairnSi 0. At this condition it means that the whole incidence sun light will be absorbed in to Si solar cell diode. As an additional information that refractive index of Si nSi in the visible spectrum range and nair 1 such that to obtain R 0 then required to use a dielectric AR coating with War Vnair nsi . The following Tabel-1 shows a list of materials with their corresponding refractive indices on the wavelength spectrum range in the region of visible and infrared 21. Material Refractive index MgF2 - Al2C3 - Si3N4 - SiC2 - SiC - TiC2 ZnS - Ta2C5 - HfC2 - Tabel 1. List of Refractive Indices of Dielectric Materials To obtain a minimum reflectance with a single thin film layer AR we can apply Al2C 3 Si3N4 SiC or HfC2 single layer. Other material can be used as AR in multi layer thin-film structure with the consequence of higher fabrication cost. Textured Surfaces The other method used to reduce reflectance and at the

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