The effects of heat treatment temperature on the hardness and slicing performance of multi-crystalline silicon brick was investigated.The hardness of the samples treated at 800℃

1 000℃and 1 100℃is increased

while that of the samples treated at 1 150℃is slightly decreased

and declined significantly at 1 200℃.The slicing performance of bricks treated above 1 200℃is desirable

and the defects such as saw mark

chipping

total thickness variation（TTV）occurred in the slicing process with diamond wire slicer are substantially improved.However

the photoelectric conversion efficiency of the battery piece made of multi-crystalline silicon brick by the conventional process after above-mentioned process is reduced significantly

which may be attributed to the diffusion of impurity elements into the brick during the heat treatment process

affecting the photoelectric conversion efficiency of the cell.