High-Efficiency and Stable Inverted Planar Perovskite Solar Cells with Pulsed Laser Deposited Cu-Doped NiO Hole-Transport Layers.

High-quality hole-transport layers (HTLs) with excellent optical and electrical properties play a significant role in achieving high-efficient and stable inverted planar perovskite solar cells (PSCs). In this work, the optoelectronic properties of Cu-doped NiO (Cu:NiO) films and the photovoltaic performance of PSCs with Cu:NiO HTLs were systematically studied. The Cu-doped NiO with different doping concentrations was achieved by a high-temperature solid-state reaction, and Cu:NiO films were prepared by pulsed laser deposition (PLD). Cu ion dopants not only occupy the Ni vacancy sites to improve the crystallization quality and increase the hole mobility, but also substitute lattice Ni sites and act as acceptors to enhance the hole concentration. As compared to the undoped NiO films, the Cu:NiO films exhibit a higher electrical conductivity with a faster charge transportation and extraction for PSCs. By employing the prepared Cu:NiO films as HTLs for the PSCs, a high photocurrent density of 23.17 mA/cm and a high power conversion efficiency of 20.41% are obtained, which are superior to those with physical vapor deposited NiO HTLs. Meanwhile, the PSC devices show a negligible hysteresis behavior and a long-term air-stability, even without any encapsulation. The results demonstrate that pulsed laser deposited Cu-doped NiO film is a promising HTL for realizing high-performance and air-stable PSCs.