One-step constructed dual interfacial layers for stable perovskite solar cells

The highly efficient perovskite solar cells (PSCs) along with excellent long-term stability can be obtained by fabricating two-dimensional (2D) perovskites (PVKs) over the three-dimensional (3D) PVKs film. However, the additional step of forming 2D PVKs before depositing the hole/electron transporting layer would make the device fabrication processes complicated, increasing costs for the manufacture of PSCs. In the present work, 2D PVKs were in-situ formed on surface of the 3D PVKs film by a self-assembly method, together with the deposition of the hole transporting material (HTM) at the same time, which tremendously simplified the fabrication of PSCs based on 3D PVKs/2D PVKs. Based on the one-step constructed 2D PVKs/HTM dual interfacial layers, density of trap states in devices were decreased remarkably owing to efficient interfacial passivation. In the meantime, the hydrophobicity, conductivity and hole extraction ability of the HTM were generally improved, enhancing the operational stability and performance of the solar cells. Thus, the corresponding solar cells increased 10% of average power conversion efficiency, where the highest open circuit voltage is up to 1.174 V. After 672 h of exposure under full 1-sun simulation in ambient conditions, the device still retained more than 82% of its initial PCE which was almost 50% higher than that of the control device.