Efficient fully-vacuum-processed perovskite solar cells using copper phthalocyanine as hole selective layers

The state-of-the-art organic-inorganic lead halide perovskite solar cells use organic materials as hole selective layers that are unstable, thermally and chemically, and expensive. Here we demonstrate efficient room-temperature fully-vacuum-processed planar perovskite solar cells using small-molecule organic copper phthalocyanine (CuPc), which has chemical and thermal stability while also being relatively inexpensive, as the hole selective material. The best-performing planar perovskite solar cell using a CuPc hole selective layer achieved a power conversion efficiency of 15.42% with an open circuit voltage of 1.04 V and a fill factor of 77.47%, measured under reverse voltage scanning, and a steady-state efficiency of 14.5%. The cell showed improved stability as compared to reference cells using conventional organic hole selective layers. Our results suggest that thermally evaporated CuPc is an excellent hole selective material for fabricating large-area and low-cost flexible perovskite solar cells with good long-term stability.