Chlorobenzene: A Processing Solvent Enabling the Fabrication of Perovskite Solar Cells with Consecutive Double-Perovskite and Perovskite/Organic Semiconductor Bulk Heterojunction Layers

Chlorobenzene (CB), which has been used as an anti-solvent, is demonstrated here as a processing solvent for the fabrication of perovskite films and solar cells. This approach results from the unexpected finding that butylamine-bound organolead iodides can be dissolved in CB to form precursor solutions. Together with previously established perovskite composition transformation methods, not only conventionally structured perovskite solar cells (PSCs) with a (CH3NH3)PbI3 active layer but also nonconventionally structured devices with a consecutive (CH3NH3)PbI3/(C4H9NH3)(2)PbI4 double layer or a mixed poly(triaryl amine) (PTAA) and (CH3NH3)PbI3 bulk heterojunction layer are successfully prepared and demonstrated with an optimal efficiency of 16.44%. This is the first time that nonpolar solvents are used for perovskite material processing, which can remove the solvent limitation and open a new avenue for designing and preparing perovskite devices with desired structures.