C-60 Thin Films in Perovskite Solar Cells: Efficient or Limiting Charge Transport Layer?

In this work, we identify the importance of C-60 and compact-TiO2 (cTiO(2)) as electron transport layers on the device performance of coevaporated n-i-p perovskite solar cells. We found (1) a synergetic effect between both layers when extracting the charges and (2) that optimization of the C-60 layer is essential for obtaining devices with enhanced device performance. In particular, we found that a C-60 layer of an optimum thickness (20 nm), an additional charge transport resistance is observed by impedance analysis, indicating that devices with nonoptimized C-60 thickness could limit the fabrication of highly efficient perovskite solar cells.