Injected charge extraction by linearly increasing voltage for bimolecular recombination studies in organic solar cells

We present a technique called “injected charge extraction by linearly increasing voltage” (i-CELIV) and apply it to evaluate bimolecular recombination in organic solar cells. The experimental setup is straightforward requiring no laser or optical-electrical pulse synchronization. The applicability of the method is discussed and non-Langevin recombination in a model poly(3-n-hexylthiophene) (P3HT):phenyl-C61-butyric acid methyl ester (PC60BM) solar cell is quantified and confirmed. Further, Langevin recombination in the low optical gap high efficiency blend, poly[2,6-(4,4-bis-{2-ethylhexyl}-4H-cyclopenta[2,1-b;3,4-b′]-dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)]:phenyl-C71-butyric acid methyl ester is reported using i-CELIV.