Effects on the open-circuit voltage of grain boundaries within the junction space-charge region of polycrystalline solar cells

A physical explanation is given for the observed dependence of open-circuit voltage on grain size in polycrystalline solar cells when no such dependence is seen for short-circuit current. This explanation identifies carrier recombination through grain-boundary surface states within the junction space-charge region as a primary mechanism underlying these dependencies. Experimental data that support this explanation are discussed, and possible ways of improving the conversion efficiency of polycrystalline solar cells are indicated.