Controlled growth of PbI 2 nanoplates for rapid preparation of CH 3 NH 3 PbI 3 in planar perovskite solar cells (Phys. Status Solidi A 12∕2015)

Abstract

Absorbers for planar perovskite solar cells are often prepd. by two-step deposition methods, where a thick compact PbI2 layer is deposited followed by conversion to perovskite using CH3NH3I soln. The surface of the precursor layer quickly reacts with the CH3NH3I soln., which hinders further diffusion of CH3NH3I into the layer, consequently leading to significant amts. of residual PbI2 at room temp. Here, we report a novel concept that employs a porous nanostructured PbI2 layer consisting of nanoplates to rapidly prep. single phase perovskite layer. The non-compact nanoplate morphol. is achieved in a controllable manner by thermal evapn. of PbI2 on TiO2-coated FTO substrate and allows easy penetration of CH3NH3I soln. into the whole PbI2 layer, thus facilitating fast and complete conversion. The amt. of PbI2 residual can be controlled by varying the CH3NH3I concn. The growth of the nanoplates is governed by the intrinsic crystallog. structure of the deposited material, crystal characteristics of the underlying substrate, and deposition method. The introduced process enables planar perovskite solar cells with efficiency of 8.6% measured at max. power point. This work opens a new route for rapid prepn. of other three-dimensional org.-inorg. hybrid perovskites by rational tailoring the metal halide morphol. [on SciFinder(R)]