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

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/C₆₀ 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 cm² 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.