By means of femto-second time-resolved spectroscopy, we investigated the carrier formation process against film morphology and temperature (T) in highly-efficient organic photovoltaic, poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′] dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b] thiophenediyl]] (PTB7)/[6,6]-phenyl C71-butyric acid methyl ester (PC70BM) solar cells. We found that the carrier formation efficiency (ϕCF) from an absorbed photon is nearly independent of the film morphology, indicating that the internal quantum efficiency (ϕIQ) is mainly governed by the carrier transfer efficiency (ϕCT) to the electrodes. The activation energy (Ea=0.5–0.8 meV) of ϕCF is significantly low, which suggests an extended charge-transfer state around the PTB7/PC70BM interface.