Efficiencies of perovskite hybrid solar cells influenced by film thickness and morphology of CH₃NH₃PbI_3-xCl_x layer

Perovskite hybrid solar cells (pero-HSCs) have been intensively investigated due to their promising photovoltaic performance. However, the correlations between the efficiencies of pero-HSCs and thin film thicknesses and morphologies of CH₃NH₃PbI_3-xCl_x perovskite layers are rarely addressed. In this study, we report the correlation between the efficiencies of "planar heterojunction" (PHJ) pero-HSCs and the thin film thicknesses and morphologies of solution-processed CH₃NH₃PbI_3-xCl_x perovskite layers. Investigation of absorption spectra, X-ray diffraction patterns, atomic force microscopy and scanning electron microscopy images of CH₃NH₃PbI_3-xCl_x layers indicate that the efficiencies of PHJ pero-HSCs are dependent on the film thickness, as the thickness of CH₃NH₃PbI_3-xCl_x is less than 400 nm; whereas the efficiencies are significantly dependent on the film morphologies of CH₃NH₃PbI_3-xCl_x layers as the thickness is larger than 400 nm. Our studies provide a promising pathway for fabricating high efficiency PHJ pero-HSCs.