Two different mechanisms of CH3NH3PbI3 film formation in one-step deposition and its effect on photovoltaic properties of OPV-type perovskite solar cells

摘要: Although the one-step deposition method has intensively been studied because of simple and easy fabrication perovskite films, uncontrolled crystallization during often results in films with small crystallites low surface coverage, leading to photovoltaic performance. In this study, we have proposed optimum processing conditions afford a favorable crystal morphology for achieving high power conversion efficiency solar cells. Two different morphologies, tree-like flower-like are developed depending upon spin-coating time post-heat treatment temperature. When is crystallized from liquid film after short time, developed, whereas when long time. evolution monitored using situ optical microscopy X-ray diffraction investigate origin difference between it reveals that CH3NH3I–PbI2–solvent complex formed develop before CH3NH3PbI3 crystals formed, directly without formation complex. The morphology, as prepared DMSO solution, large-sized crystallites, highly orientated along (112) (200) directions, resulting PCE 13.85%, small-sized random orientation, exhibiting very PCEs.