Benefits of very thin PCBM and LiF layers for solution-processed p–i–n perovskite solar cells

Abstract

Highly efficient p–i–n perovskite solar cells employing a flat and thick CH₃NH₃PbI₃ film and a thin PCBM film are fabricated by the solution-process at low temperature. Through attainment of optimized PCBM thickness and insertion of the LiF interlayer, the unit cell shows 14.1% of overall power conversion efficiency (PCE) with a J_sc of 20.7 mA cm⁻², a V_oc of 0.866 V, and a FF of 78.3% under AM 1.5G 100 mW cm⁻² conditions, while a larger area 10 cell serially connected module (10 × 10 cm²) shows an 8.7% PCE. These PCE values are the highest reported to date for the planar perovskite–PCBM solar cells.