A general fabrication procedure for efficient and stable planar perovskite solar cells: Morphological and interfacial control by in-situ-generated layered perovskite

Compared to the 3D lead-halide perovskites (MAPbX(3), X=I/Cl), two dimensional (2D) perovskites have more flexible structures, with more relaxed limitations in the size of the organic cations and produce interesting variant of photophysical and electronic properties. Here, a universal deposition approach for stable and efficient MAPbX(3) perovskite solar cells (PeSCs) displaying excellent reproducibility are presented via in-situ formed layered perovskites derived from polymeric ammonium anchor. The critical effect of in-situ formed layered perovskite (PEI)(2)[Pbl(4)] on the morphological and interfacial control of the above 3D perovskite are identified, and it is demonstrated that 2D perovskite films promote the formation of above perovskite films composed of micron-sized grains and provide better energy level alignment at the interface. Moreover, the incorporation of great moisture-resistant 2D materials, accompanying uniform and dense MAPbX(3) films enhances long-term stability of the perovskite solar cells. As a result, a maximum PCE value of 13.8% for MAPbl(3) solar cells on flexible substrate are achieved in ambient air. It is anticipated that our strategies to design and explore low dimensional perovskites can provide alternative route to address the critical concerns of stability and reproducibility in PeSCs. (C) 2015 Published by Elsevier Ltd.