Experimental test for geminate recombination applied to organic solar cells

We show that a clear experimental test can distinguish between geminate and nongeminate recombination in low mobility semiconductors. For the particular case of the organic solar cell, the relative contribution of geminate recombination can be determined by measuring transient photoconductivity versus applied voltage. Measurements carried out at room temperature and 200 K on bulk heterojunction organic solar cells fabricated with two different semiconducting polymers show that neither exhibits significant geminate recombination.