Solution-processed room temperature nickel oxide hole transport layer for perovskite solar cells

Abstract

Nickle oxide (NiOx) dispersion coated at room temperature was prepared, acting as a hole transport layer for perovskite optoelectronics. The selectivity of the electrodes in a perovskite solar cell device strongly affects the device's performance and stability. This can be achieved by inserting semiconductor thin films with suitable energy levels and electrical conductivity between the perovskite active layer and the electrodes in the device. Different types of metal oxide-based interlayers with large variations in their electrical properties have been utilized as electron and hole transport layers. In this regard, a nickel oxide hole transport layer has demonstrated excellent results. The nickel oxide layer, which is about 10 nm thick, is fabricated by sputtering deposition or by a nickel oxide precursor with a high-temperature post-thermal annealing treatment in air between 200 °C and 300 °C. The perovskite active layer can be processed by wet coating methods and thermal treatments at much lower temperatures. It is, therefore, more cost-effective and product-compatible to fabricate solution-processed nickel oxide at room temperature. Here, we report a stable dispersion of nickel oxide nanoparticles in water processed at room temperature. The nickel oxide film was coated in air without any need for post-treatment, leading to a condensed nickel oxide (NiOx) film with suitable properties acting as an optimum hole transport layer for perovskite solar cells. This report demonstrates a solar cell device with an inverted structure based on solution-processed room temperature nickel oxide dispersion with high efficiency and good stability under maximum power point (MPP) conditions.