Insights into the Hole Blocking Layer Effect on the Perovskite Solar Cell Performance and Impedance Response

The implementation of efficient hole blocking layers (BLs) is of vital importance to achieve high efficiency in solar cells using organolead trihalide materials as the solar light absorber. BLs permit electronic charge separation and avoid the recombination of charges by blocking the hole transfer to the anode. In this study, BLs have been prepared by aerosol spray pyrolysis and spin-coating using various solution compositions. The morphological, optical, microstructural and crystalline properties as well as the phase composition of these layers have been characterized by scanning electron microscopy, Raman spectroscopy, and optical measurements. Their blocking ability has been evaluated by cyclic voltammetry. A strong relationship has been found between these properties and the solar cell J–V characteristics and performances. Overall, we figured out that the sprayed BLs were thin, highly compact, covering, and conformal. No cracks or pinholes were found because the precursor underwent degradation and con...