A promising concept to push efficiency of pn-junction photovoltaic solar cell beyond Shockley and Queisser limit based on impact ionization due to high electric field

This paper studies the implication of impact ionization due to a high electric field on the improvement of the photovoltaic solar cell efficiency. A high electric field existing in the space charge region (SCR) of the solar cell induces the generation of additional free carriers by accelerating the photogenerated electron-hole pairs which collide with the lattice of the semiconductor material. The resultant current taking into account this carriers' multiplication (CM) is calculated and the maximum efficiency of the photovoltaic solar cell is evaluated. The found results show that CM in photovoltaic solar cell occurs in a definite range of the electric field near to the pn-junction and could improve significantly his efficiency for more than 5% at an electric field less than 4 x 10(5) V/cm, depending on the width of the space charge region or the multiplication region. The usable range of the electric field for CM in solar cell is linked to the type of semiconductor material used.