Fig 7 shows the J-V curve and error bars of the CZTSe solar cell using the RTA-CZTSe as absorber under illuminated condition.The cell efficiency error is at the range of 0.1% caused by the test error of lighting area.The champion device represents a power conversion efficiency of 4.5%, which is the highest cell efficiency for electrodeposited CZTse solar cells so far.The device gives an open circuit voltage of Voc=307mV and remarkable high photocurrent of Jsc 38.81 mA/cm where the fill factor(FF )is37.4. The present CZTSe cell has relatively low Voc and high Jsc, which is expected from its low band gap.In principle, the cell efficiency should increase with band gap until it reaches the theoretical optimum value of 1.45 ev for AM1.5G illumination.