New Low-temperature Solution Processes to Control the Formation of Perovskite Films for Achieving High Performance Solar Cells

摘要

New low-temperature processing schemes for controlling of perovskite film in the typical one-step and two-step approaches will be discussed in this work. For one-step method, we propose the scheme of vacuum assisted low-temperature annealing process to control the composition and morphology of triiodide (CH_3NH_3PbI_3) film from 3CH_3NH_3I:PbCl_2. Besides, the approach allows us to identify the critical role of the by-produced of CH_3NH_3CI on the film formation and the device performance. As a result, perovskite solar cells (PVSCs) achieve good stability, reproducibility, PCE and no hysteresis. For two-step method, we propose the formation of PBI_2 nanostructure together with strategically high ch_3nh_3i concentration to (1) form smooth CH3NH3PBI3 film on flat substrate without PbI_2 residue at roomtemp, and (2) enhance photovoltaic performance and stability of planar-heterojunction PVSCS.