Structuring of surface for light management in monocrystalline Si solar cells

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2015
Bilgen, Sedat
Texturing of a silicon wafer is the first process of production of screen printed solar cells to reduce the reflection losses by producing pyramids on the surface of the silicon wafer. Being a cheap and time efficient process, texturing is used in all industrial applications. For mono-crystalline silicon wafers, the process is carried out by using an alkaline solution which consists of potassium hydroxide (KOH), isopropyl alcohol (IPA) and de-ionized water (DI-water) which is heated to 75- 80oC, and wafers are put in it up to a certain time to get random pyramids on the surface. These pyramids reduce the reflection and increase light trapping, and thus increase the efficiency. In this study, the magnetic agitation was used to optimize the process parameters like, the concentrations of KOH and IPA, process temperature, and process time. To minimize the process duration and process temperature, ultrasonic agitation was used, and almost uniformly distributed small pyramids (3 μm in average) were obtained. To observe the surface characteristics, reflection vi measurements and SEM images were taken. Then, the simulations of uniformly textured wafers with textured one side and two sides were made to observe the absorption ability with different thicknesses and different pyramid heights. Then, solar cells were fabricated by using new process parameters and agitation. To characterize the solar cells, reflection, external quantum efficiency (EQE), current-voltage (I-V), and Suns-Voc measurements were carried out. It was observed that cells based on wafers textured with new parameters and ultrasonic agitation could be used to reach higher conversion efficiency values compared to reference cells.

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Citation Formats
S. Bilgen, “Structuring of surface for light management in monocrystalline Si solar cells,” M.S. - Master of Science, Middle East Technical University, 2015.