Facet orientation tailoring via 2D-seed- induced growth enables highly efficient and stable perovskite solar cells

Adding 2D perovskite to 3D perovskite has been developed to effectively enhance the intrinsic stability, but it will inevitably compromise the power conversion efficiency (PCE). Here, in a novel way, we introduced highly oriented 2D (BDA)PbI4 perovskites as seeds to optimize the growth kinetics of 3D perovskite and make its crystallization directly stride over the nucleation stage. Therefore, the seeds preferentially act as templates to epitaxially grow 3D perovskite with the desired facet orientation and stacking mode. Moreover, the 2D seeds are transformed into the grain boundary after completing the orientation-induced growth. As a result, the high-quality mixed-dimensional perovskite film delivers a superior PCE of 23.95%, accompanied by a remarkable FF of 0.847. The unencapsulated Perovskite solar cell (PSC) retains 93% of its original efficiency after 1,056 h of storage and retains 91% of its initial efficiency after 500 h of operation at the maximum power point under simulated AM1.5 illumination at 60°C.