Nanoparticulate Metal Oxide Top Electrode Interface Modification Improves the Thermal Stability of Inverted Perovskite Photovoltaics

Solution processed γ-Fe(2)O(3) nanoparticles via the solvothermal colloidal synthesis in conjunction with ligand-exchange method are used for interface modification of the top electrode in inverted perovskite solar cells. In comparison to more conventional top electrodes such as PC(70)BM/Al and PC(70)BM/AZO/Al, we show that incorporation of a γ-Fe(2)O(3) provides an alternative solution processed top electrode (PC(70)BM/γ-Fe(2)O(3)/Al) that not only results in comparable power conversion efficiencies but also improved thermal stability of inverted perovskite photovoltaics. The origin of improved stability of inverted perovskite solar cells incorporating PC(70)BM/ γ-Fe(2)O(3)/Al under accelerated heat lifetime conditions is attributed to the acidic surface nature of γ-Fe(2)O(3) and reduced charge trapped density within PC(70)BM/ γ-Fe(2)O(3)/Al top electrode interfaces.