Fig. 4. Analysis of recombination and transport in PffBT4T-2DT based devices. (A) Effective device mobility μ _CE as a function of charge carrier density, measured by charge extraction at short circuit for PffBT4T-2DT:PCBM (green) and PffBT4T-2DT:FBR (blue). (B) Langevin recombination rate constant (circles) and the measured bimolecular recombination rate (open squares) measured from TPV and CE at open circuit (ESI†).