Among the different recombination mechanisms in organic solar cells the photoluminescence (PL) of charge transfer excitons (CTEs) has been identified has one of the most important, impacting both the open circuit voltage and the short circuit current. Here, we study their recombination dynamics, monitoring the decay of the PL on a time scale spanning three orders of magnitude from nanoseconds to microseconds. As a model system we investigate blends of the conjugated polymer poly(2-methoxy-5-(3′,7′-dimethyloctyloxy)-l,4- phenylene-vinylene) (MDMO-PPV) and the fullerene derivative [6,6]-phenyl C ₆₁-butyric acid methyl ester (PCBM). We observe that the dynamics of recombination follows a power-law, which is independent of sample morphology. Upon application of a transient electric field, which is capable of separating the bound charge pairs, we observe different dynamics of recombination only for the separated pairs. Those also follow a power-law and show a strong dependence on the film morphology.