Towards All-Inorganic Transport Layers for Wide-Band-Gap Formamidinium Lead Bromide-Based Planar Photovoltaics

Hybrid perovskite photovoltaic devices heavily rely on the use of organic (rather than inorganic) charge-transport layers on top of a perovskite absorber layer because of difficulties in depositing inorganic materials on top of these fragile absorber layers. However, in comparison to the unstable and expensive organic transport materials, inorganic charge-transport layers provide improved charge transport and stability to the device architecture. Here, we report photovoltaic devices using all-inorganic transport layers in a planar p-i-n junction device configuration using formamidinium lead tri-bromide (FAPbBr(3)) as an absorber. Efficient planar devices are obtained through atomic layer deposition of nickel oxide and sputtered zinc oxide as hole-and electron-transport materials, respectively. Using only inorganic charge-transport layers resulted in planar FAPbBr(3) devices with a power conversion efficiency of 6.75% at an open-circuit voltage of 1.23 V. The transition of planar FAPbBr(3) devices making from all-organic towards all-inorganic charge-transport layers is studied in detail.