Commercial Si Solar Cell Efficiency Improvement by Gamma Radiation, Plasma Treatment and Oxides Front Layer Depositions

In this work the potential of atmospheric agents such as gamma rays and plasma on conventional solar cell efficiency has been followed. Improving the device performance by depositing a ZnO or SrTiO3 layer on the front surface of both monocrystalline and polycrystalline Si cells has been also achieved. The electrical parameters detected by measuring the I-V characteristic are discussed. The results were analyzed using modified thermal emission theory to estimate the barrier height (Bo), ideality factor (n), series and shunt resistances (Rs and Rsh). Gamma irradiation at 1 kGy increased VOC, Isc, Vmp, and Imp, hence the maximum output power (Pm) and efficiency (η) of both cell types. Concerning the dense plasma focus (DPF) effect, H2 gas flow was detected to increase the efficiency by 16.5% and 22.5%, respectively for monocrystalline and polycrystalline cells. The potential effect of the deposition of a thin layer of SrTiO3 (SrTiO3/Si) or ZnO (ZnO/Si) led to efficiency improvement of 24% and 23%, respectively for monocrystalline cells. The effect of light trapping and the reduction of recombination by the front layer on cell performance and the role played by grain boundaries of polycrystalline cells were discussed.