Ammoniated aqueous precursor ink processed copper iodide as hole transport layer for inverted planar perovskite solar cells

The inorganic carrier transport layers are robust and stable to the environment compared to the organic hole transport layer (HTL). Here, we report on the fabrication of the halide perovskite solar cells (HaPSCs) employing CuI deposited with ammoniated aqueous solution ink as HTL and explored the material properties and device characteristics. The film morphology of CuI is found to have an influence on the HaP film growth and hence effects on the device parameters. The HaPSC with CuI has demonstrated the power conversion efficiency of similar to 14.21% with high reproducibility. The capacitance spectra analysis shows that the deep trap states are induced in the perovskite absorber layer. The results obtained from the temperature-dependent open circuit voltage implicates that the recombination activities in the perovskite bulk are dominant. Furthermore, the HaPSC with CuI has revealed better air stability compared to the device with PEDOT:PSS. This work suggests that the CuI processed with aqueous precursor is a promising alternative HTL to PEDOT:PSS for efficient and stable perovskite solar cells as well as in a tandem device.