Luminescence of solar cells with $a$-Si:H/$c$-Si heterojunctions

We have studied the electroluminescence (EL) and photoluminescence (PL) of solar cells containing $a$-Si:H/$c$-Si heterojunctions. It is established that both the EL and PL properties of these cells are determined by the radiative recombination of nonequilibrium carriers in crystalline silicon ($c$-Si). The external EL energy yield (efficiency) of solar cells with $a$-Si:H/$c$-Si heterojunctions at room temperature amounts to 2.1% and exceeds the value reached in silicon diode structures. This large EL efficiency can be explained by good passivation of the surface of crystalline silicon and the corresponding increase in lifetime of minority carrier s in these solar cells.