Vacuum-Assisted Thermal Annealing of CsPbI 3 for Highly Stable and Efficient Inorganic Perovskite Solar Cells.

Inorganic cesium lead iodide perovskite CsPbI 3 is attracting great attention as a light absorber for single or multi-junction photovoltaics due to its outstanding thermal stability and proper band gap. However, the device performance of CsPbI 3 -based perovskite solar cells (PSCs) is limited by the unsatisfactory crystal quality and thus severe non-radiative recombination. Here, vacuum-assisted thermal annealing (VATA) is demonstrated as an effective approach for controlling the morphology and crystallinity of the CsPbI 3 perovskite films formed from the precursors of PbI 2 , CsI, and dimethylammonium iodide (DMAI). By this method, a large-area and high-quality CsPbI 3 film is obtained, exhibiting a much reduced trap-state density with prolonged charge lifetime. Consequently, the solar cell efficiency is raised from 17.26 to 20.06 %, along with enhanced stability. The VATA would be an effective approach for fabricating high-performance thin-film CsPbI 3 perovskite optoelectronics.