Selective Templating Growth of Wide-Bandgap Perovskites via Vertical Additive Gradients for 26.51%-Efficient...

Precise control over the crystallization and growth of wide-bandgap (WBG) three-dimensional (3D) perovskite is essential for achieving high photovoltaic performance and enabling efficient tandem solar cells (TSCs). Herein, we report a selective templating growth (STG) strategy utilizing trimethylsulfonium iodide (TMSI) to regulate the crystallization dynamics of WBG perovskites. The strong coordination and templating capability of TMSI facilitate the in-situ formation of a one-dimensional (1D) perovskite intermediate, which uniquely directs the preferential (100) orientation and enhancing the lattice coherence within the resulting 3D perovskite framework. Moreover, a vertical concentration gradient of TMS⁺ ions modulates crystallization kinetics, extending the time window for halide homogenization while simultaneously enabling effective grain boundary passivation through anchored PbI₂ nanosheets. As a result, optimized WBG perovskite solar cells (PSCs) deliver a champion power conversion efficiency (PCE) of 19.71%, accompanied by an enhanced open-circuit voltage (V_OC) of 1.35 V and significantly improved photostability. When integrated into monolithic perovskite/organic TSCs, the devices achieve a notable PCE of 26.51%. This work establishes a mechanistically grounded strategy for regulating perovskite crystallization through intermediate-phase templating, offering a viable pathway toward high-performance WBG absorbers for the next-generation multi-junction photovoltaics.