High quality multi-crystalline silicon wafer by grain size control on directional growth method

In recent year, efficiency of multi-crystalline silicon (mc) solar cell had large improvement due to better quality of wafer source. In continental thought, grain boundaries and dislocations are act as recombination center of photo-electrons. Large grain size wafers has lower density of grain boundary and should has higher percentage of converge efficiency. However, in recent year, wafers in small grain size have low dislocation density dominate the mc-solar cell industry and improve the average efficiency of solar cell more than 0.25%.