Graphene-engineered automated sprayed mesoscopic structure for perovskite device scaling-up

One of the most thrilling developments in the photovoltaic field over recent years has been the use of organic–inorganic lead halide perovskite, such as CH3NH3PbI3 (MAPbI3), as a promising new material for low-cost and highly efficient solar cells. Despite the impressive power conversion efficiency (PCE) exceeding 22% demonstrated on lab-scale devices, large-area material deposition procedures and automatized device fabrication protocols are still challenging to achieve high-throughput serial manufacturing of modules and panels. In this work, we demonstrate that spray coating is an effective technique for the production of mesoscopic small- and large-area perovskite solar cells (PSCs). In particular, we report a sprayed graphene-doped mesoporous TiO2 (mTiO2) scaffold for mesoscopic PSCs. By successfully combining the spray coating technique with the insertion of graphene additive into the sprayed mTiO2 scaffold, a uniform film deposition and a significant enhancement of the electron transport/injection at the mTiO2/perovskite electrode is achieved. The use of graphene flakes on the sprayed scaffold boosts the PCE of small-area cells up to 17.5% that corresponds to an increase of more than 15% compared to standard cells. For large-area (1.1 cm2) cells, a PCE up to 14.96% is achieved. Moreover, graphene-doped mTiO2 layer enhances the stability of the PSCs compared to standard devices. The feasibility of PSC fabrication by spray coating deposition of the mesoporous film on large-area 21  ×  24 cm2 provides a viable and low-cost route to scale up the manufacturing of low-cost, stable and high-efficiency PSCs.