Impurity photovoltaic effect in crystalline silicon solar cells

For effect of impurity traps for efficiency improvement of solar cells (called impurity photovoltaic effect) has been investigated by measuring optical absorption and characteristics of crystalline silicon solar cells. Energy level and spatial position of the impurity traps, and compensation of charges caused by the traps are definite requirements to improve the cell efficiency by the IPV effect under suppression of carrier recombination. Indium is selected as one of the proper impurities that satisfy these requirements in crystalline silicon. For indium introduced crystalline silicon solar cell, it is possible to increase the photocurrent without degrading the values of open circuit voltage. It is concluded that the IPV effect is useful to improve the cell efficiency.