CH3NH3Cl-Assisted One-Step Solution Growth of CH3NH3PbI3: Structure, Charge-Carrier Dynamics, and Photovoltaic Properties of Perovskite Solar Cells

We demonstrate a novel one-step solution approach to prepare perovskite CH 3 NH 3 PbI 3 films by adding CH 3 NH 3 Cl (or MACl) to the standard CH 3 NH 3 PbI 3 precursor (equimolar mixture of CH 3 NH 3 I and PbI 2 ) solution. The use of MACl strongly affects the crystallization process of forming pure CH 3 NH 3 PbI 3, leading not only to enhanced absorption of CH 3 NH 3 PbI 3 but also to significantly improved coverage of CH 3 NH 3 PbI 3 on a planar substrate. Compared to the standard one-step solution approach for CH 3 NH 3 PbI 3, using MACl improves the performance of CH 3 NH 3 PbI 3 solar cells from about 2% to 12% for the planar cell structure and from about 8% to 10% for the mesostructured device architecture. Although we find no significant effect of using MACl on charge transport and recombination in mesostructured perovskite cells, the recombination resistance for planar cells increases by 1–2 orders of magnitude by using MACl. These results suggest that this new one-step solution approach is promising for controlling CH 3 NH 3 PbI 3 growth to achieve high-performance perovskite solar cells.