Fig. 2From: 5-nm LiF as an Efficient Cathode Buffer Layer in Polymer Solar Cells Through Simply Introducing a C60 InterlayerTapping mode AFM height (top) and phase (bottom) images of P3HT:PCBM, P3HT:PCBM/C60 (35 nm), P3HT:PCBM/LiF (5 nm), and P3HT:PCBM/C60 (35 nm)/LiF (5 nm) films. The corresponding root-mean-square (rms) roughnesses are 0.81, 1.36, 1.67, and 2.18 nm, respectivelyBack to article page