Solvent-free deposition of hybrid halide perovskites onto thin films of copper iodide p-type conductor

We demonstrate that a widely used inorganic holetransporting material, copper iodide (CuI), gets dissolved if halide perovskites are deposited atop from solutions which compromises the fabrication of CuI/perovskite heterojunctions using these methods. On the contrary, solvent-free approaches allow for the retaining of the CuI layer under the halide perovskite film thus making this approach beneficial for the development of perovskite photovoltaics.