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Title: FWI Institutskolloquium: Defects in cast quasi-single crystalline silicon for solar cells
Category: Colloquium
Begin: 19.09.2019 10:30
End: 19.09.2019 12:00
Speaker: Prof. Deren Yang, State Key Lab of Silicon Materials and School of Material Science and Engineering, Hangzhou, Zhejiang University
Contact: Shengqiang Zhou
Location: 106/255 - Hörsaal
Content: Abstract: Crystalline silicon is the main material in photovoltaic (PV) industry, and occupies more than 90% market shares. To lower cost, man has improved the quality of crystalline silicon and increased the efficiency of solar cells. In recent, cast quasi-single crystalline (QSC) silicon has attracted much attention because it inherits the advantages of both Czochralski (Cz)- and multicrystalline (mc)-silicon. QSC Si is mostly single crystalline and could be texturized by sodium hydroxide to lower reflectivity. Therefore, QSC Si should be lower cost and higher efficiency. However, defects in QSC Si have seriously influenced on the quality of crystalline silicon and cut down the efficiency of solar cells. In this talk, the recent work in my group about the defects in QSC Si ingots, wafers and solar cells will be presented. It is considered that dislocation in QSC Si is an important factor that largely influences on the electrical properties, especially when the dislocation density is higher than 1*106 /cm2. Moreover, the dislocation density of QSC-silicon must be controlled within an acceptable range in the crystal growth process. By inducing suitable grain boundaries, the density of random dislocations could be suppressed. The results could help better understand the QSC Si and boost its application in industry.