Spray coating as scalable deposition technique of TiO2 blocking layer to boost the perovskite solar cell performances

To achieve high efficiency, the blocking layer (BL) is of critical importance in perovskite solar cells.
Indeed, substrate has to be covered by a dense TiO2 film to prevent short circuits in the final PV cell.
In this study, we compare the spin coating (SC) technique - commonly used for the TiO2 blocking
layer deposition in solid-state methylammonium lead triiodide perovskite (MaPbI3)-based solar cells - with
ultrasonic spray pyrolysis (USP). Ultrasonic spray coating is a promising non-vacuum pathway to
manufacture blocking layer that can be implemented from laboratory to industrial scale.
The BL microstructure is characterized by scanning electron microscopy (SEM) and X-Ray
diffraction (XRD). Although both deposition techniques lead to similar coating thickness and structure, the
cyclic voltammetry measurements highlight the higher blocking capability of the ultrasonic spray pyrolysis
BL. The BLs were tested in complete solar cell devices. Performance of perovskite solar cells is discussed
and related to the morphology and the conductivity of the TiO2 blocking layers.