Perovskite solar cells are an emerging research field which underwent an outstanding development towards very high efficiencies. Here we show an elegant and novel approach to create a bilayer of perovskite and polymeric hole conductor from a blend of the precursors for perovskite and the polymer in a one-pot fabrication method.
The strategy involves a crystallization driven macrophase separation leading to a desired vertical layered structure. This is realized by using a poly(tetraphenylbenzidine) (PTPD) polymer which is soluble in polar solvents such as γ-butyrolactone and N-methylpyrrolidone, in which both PbI2 and CH3NH3 Introduction I also dissolve. Thus, a homogeneous solution of all the three components could be prepared at elevated temperatures.
After solution casting from the precursor solution the crystallization of the perovskite is carried out. During the crystallization process, the blend system phase separates leading to a layered structure of the crystallized perovskite at the bottom and the hole transporting polymer layer on top. The annealing protocol as well as the solar cell preparation and characterization are given.
This method is used here for the first time and it is an elegant tool to reduce the processing steps for perovskite solar cells making them even more interesting for the use in large are applications. We obtain large crystals of perovskite with well-defined interfaces as observed in scanning electron microscopy.
Neumann, K. and Thelakkat, M., Crystallization-driven phase separation towards one pot fabrication of bilayer pervoskite/polymer solar cells. Triphenylamine based semiconducting polymers for organic/hybrid photovoltaics and sensors, p.61.