Improving the electrical and photovoltaic properties of Si solar cells: Studying the effect of gamma rays, plasma treatments, and front layer deposition of zinc and strontium titanium oxides.

Current work focuses on the potential of atmospheric agents such as gamma rays and plasma on conventional solar cell efficiency. Improving the device performance by depositing a ZnO or SrTiO 3 layer on the front surface of both monocrystalline and polycrystalline Si cells has been 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 resistance (Rs) and shunt resistances (Rsh). Gamma irradiation at 1 kGy increased the open circuit voltage (V OC), the short circuit current (I sc), the voltage maximum point (V mp) and the current maximum point (I mp) , hence the maximum output power (P m) and efficiency (η) of both cell types. Concerning the dense plasma focus (DPF), the effect of H2 gas flow was found to increase the efficiency by 16.5 % and 22.5 %, respectively for mono and poly cells. The potential effect of the thin layer SrTiO3 (SrTiO3/Si) or ZnO (ZnO/Si) was recorded to lead to efficiency improvement of 24 % and 23 %, respectively for mono cells. Also, through SEM images, the morphology of the oxide surface was examined. The effect of light trapping and the reduction of recombination by the front layer in both SrTiO3/Si and ZuO/So cells on the PV performance and the role played by grain boundaries in polycrystalline cells were discussed. [ABSTRACT FROM AUTHOR]