Figure 5

(a) External quantum efficiency (EQE) spectra and (b) the reflectance spectra of the PSCs based on PBDTBDD:PC60BM with different cathode; (c) the additional absorption spectrum as well as additional EQE spectrum calculated from the difference of reflectance spectra and EQE spectra of the PSCs based on PBDTBDD:PC60BM with a-Zracac/Al and Al cathode, respectively.