Nanocrystal‐Nucleus Template Strategy for Efficient Wide‐Bandgap Perovskite Solar Cells with Enhanced Homogeneity and Energy‐Level Alignment

Abstract Wide‐bandgap (WBG) perovskite solar cells (PSCs) are critical for advancing tandem solar cell efficiencies, yet suffer from severe photovoltage deficits and halide segregation, substantially degrading their performance and stability. Here, a nanocrystal‐nucleus template (NCNT) strategy is developed to directly addresses heterogeneous nucleation—the root cause of phase separation—by precisely matching the I/Br ratio of nanocrystal to that of the target perovskite film. This approach guides homogeneous assembly of Pb‐I/Br octahedra, achieving exceptional halide uniformity and precise crystallization control for WBG films. The NCNT simultaneously induces p‐type doping and reduces the perovskite/C 60 interfacial energy barrier, significantly enhancing charge extraction. Remarkably, 1.68‐eV WBG PSCs fabricated via this approach achieve a record open‐circuit voltage (V OC ) of 1.30 V, alongside a champion efficiency of 23.4%. The broad applicability of this strategy is demonstrated across a wide bandgap range of 1.63–1.76 eV, all exhibiting (001)‐preferred orientation and exceptional photostability. When integrated into a 0.945 cm 2 monolithic perovskite/silicon tandem solar cell, the NCNT‐based device delivers a high efficiency of 32.0% (certified 31.7%). This work highlights the pivotal role of nanocrystals in regulating perovskite crystallization, resolves long‐standing V OC limitations in WBG perovskites, and establishes a scalable platform for next‐generation optoelectronic devices and tandem photovoltaics.