Multifunctional Cyanuric Fluoride‐Mediated Crystallization and Defect Passivation for 2D Sn‐Based Perovskite Thin‐Film Transistors

Why It Matters

The breakthrough offers a viable, lead‑free route to high‑performance perovskite TFTs, accelerating their adoption in flexible and low‑power electronics.

Key Takeaways

• Cyanuric fluoride suppresses Sn2+ oxidation.
• Mobility rises to 1.88 cm²/V·s, tenfold increase.
• Interface trap density drops to 1.8×10¹² cm⁻²eV⁻¹.
• Film uniformity improves, pinholes eliminated.
• Device retains 90% current after 2000 s bias stress.

Pulse Analysis

The push for lead‑free semiconductors has placed tin‑based halide perovskites at the forefront of next‑generation thin‑film transistor (TFT) research. Despite intrinsic p‑type conductivity and lower toxicity, Sn‑perovskites suffer from rapid Sn²⁺ oxidation, high defect densities, and poor film morphology, which have historically limited carrier mobility and operational stability. Overcoming these hurdles is critical for integrating perovskite TFTs into flexible displays, sensors, and low‑power logic circuits where traditional silicon processes are cost‑prohibitive.

In this study, cyanuric fluoride (Cy‑F) functions as a dual‑role additive, interacting strongly with both the organic phenylethylammonium (PEA⁺) cation and Sn²⁺ ions. The fluorinated ring anchors PEA⁺, promoting orderly crystallization and reducing pinhole formation, while its electronegative fluorine atoms bind to Sn²⁺, mitigating oxidation pathways. The resulting 12 vol% Cy‑F‑doped films exhibit a highly oriented crystal lattice, uniform surface coverage, and a dramatic drop in interface trap density—from 9.8×10¹² to 1.8×10¹² cm⁻² eV⁻¹. These improvements translate into a record mobility of 1.88 cm² V⁻¹ s⁻¹, surpassing the pristine device by more than an order of magnitude.

The implications extend beyond a single performance metric. Stable, high‑mobility Sn‑perovskite TFTs enable low‑voltage operation and long‑term reliability, essential for roll‑to‑roll manufacturing of wearable electronics and large‑area sensor arrays. Moreover, the additive‑based strategy is compatible with existing solution‑processing techniques, facilitating scale‑up without substantial equipment overhaul. Future work will likely explore synergistic additives, interface engineering, and encapsulation methods to further suppress environmental degradation, positioning tin‑based perovskites as a competitive alternative to both lead‑based perovskites and conventional oxide semiconductors.