Perovskite solar cells using TiO₂ layers coated with metal-organic framework material ZIF-8

A metal-organic framework of ZIF-8 is used as an interlayer between the mesoporous TiO₂ and the perovskite layer in perovskite solar cells (PSCs). The ZIF-8 solution is dried on the mesoporous TiO₂ layer, which can then act as an additional light absorbing layer at the short-wavelength range for the solar cells, leading to improved performance of the cell. After an immersion time of 1–5 min, a very thin ZIF-8 film is formed on TiO₂. An enhancement in the incident photon to current conversion efficiency (IPCE) is achieved for PSCs using the ZIF-8-coated TiO₂ layer. The conversion efficiency of PSCs is improved from 9.6 to 12.0% when ZIF-8 is present. UV–vis and photoluminescence (PL) spectra are used to investigate the beneficial effect of ZIF-8/TiO₂ hybrid layers.