Progress in Heterogeneous Nucleation-Induced Crystallization Strategies in Perovskite Solar Cells

The performance of perovskite solar cells is fundamentally capped by the crystalline quality of perovskite active layers. Conventional solution-processing lacks kinetic control over nucleation, engendering granular heterogeneity, trap-state proliferation and halide phase segregation. Heterogeneous nucleation-induced crystallization circumvents these bottlenecks by deploying extrinsic seeds or templates to engineer nucleation sites and orchestrate crystallization trajectories. This review systematically examines recent advances in this strategy. It begins by explaining the mechanisms from thermodynamic, lattice-matching and solution-chemistry perspectives, emphasizing the reduction of nucleation barriers and the guided alignment of crystal orientation. We then categorize the functional material systems, like perovskite seeds, low-dimensional materials and organic molecules. The discussion extends to the significant performance improvements achieved by this strategy in single-junction, wide-bandgap and tandem solar cells, notably in enhanced efficiency, suppressed defects and reinforced stability. Relate mechanisms for stability improvement, like grain boundary reduction, ion migration inhibition and strain release, are also discussed. Finally, we outline prospective research trajectories to provide theoretical frameworks for advancing high-efficiency and stable perovskite photovoltaics.