Researchers from Jilin University have developed a co-additive strategy to precisely regulate the crystallization of tin-based perovskites, enabling the fabrication of high-performance field-effect transistors (FETs). Tin-based perovskites are considered promising semiconductors due to their excellent charge transport properties and potential for low-temperature solution processing. However, their unstable crystallization process typically leads to low-quality films with incomplete coverage, random orientation, small grains, and high defect density, all of which hinder carrier transport and compromise device stability.
To address these challenges, the team employed 4-fluorophenethylamine acetate (FPEAAc) as a bifunctional additive to control film formation. The FPEA⁺ cations serve as structural templates, inducing the oriented growth of perovskite octahedra, while the acetate anions coordinate with Sn²⁺ ions to slow down crystallization. This balance promotes the formation of uniform films with large grains and smooth surfaces, effectively improving film quality.
Building on this strategy, the researchers introduced propylammonium acetate (PAAc) as an auxiliary additive to further modulate the crystallization rate. The combined FPEAAc/PAAc system not only allows for the growth of compact, pinhole-free films with microscale grains but also passivates grain boundaries and suppresses ionic migration, both of which are critical for device stability.
As a result, the optimized Sn-based perovskite FETs achieved a remarkable hole mobility of about 40 cm² V⁻¹ s⁻¹, among the highest values reported to date for this material system, while maintaining excellent operational stability.
This work highlights a novel approach that couples templated growth with retarded crystallization to regulate tin-based perovskite film formation. By offering new insights into microstructural control, the strategy paves the way toward high-performance and stable Sn-based perovskite electronics.
