Due to its narrow band gap and low toxicity, the lead-tin perovskite material has been widely used in fabricating perovskite solar cells. However, the poor film forming quality of lead-tin perovskite limits the improvement of battery efficiency. By adding dimethyl sulfoxide into the precursor solution to decrease the crystallization speed, a dense pinhole-free perovskite film is fabricated. Moreover, tin fluoride and fullerene derivatives are added to reduce defects in the perovskite lattice, grain boundaries and surface, which leads to the high device efficiency. The efficiency of the half lead tin perovskite solar cell prepared in this work is up to 15.1%.