Toward air-stable field-effect transistors with a tin iodide-based hybrid perovskite semiconductor.

The tin iodide-based hybrid perovskite (C₆H₅C₂H₄NH₃)₂SnI₄ [(PEA)₂SnI₄] is promising as the semiconductor in field-effect transistors (FETs) because of its easy film processability and high carrier mobility. However, the stability of (PEA)₂SnI₄ FETs in air remains a significant issue. In this study, we show that the source of this degradation is oxygen. We observed that the structure of (PEA)₂SnI₄ degraded in the presence of oxygen, along with the formation of gaps between grains. With the aim of suppressing the oxygen-induced degradation, we optimized (PEA)₂SnI₄ spin-coating conditions to increase the grain size and simply encapsulated a (PEA)₂SnI₄ semiconductor with the fluorine-based polymer CYTOP. Adopting these methods led to the greatly improved stability of FET performance in air. We propose that oxygen had reduced penetration into (PEA)₂SnI₄ films with larger grains. The drain current of optimized FETs remained almost unchanged over 5 h of operation, which is in contrast to the control device that decayed within 1 h. [ABSTRACT FROM AUTHOR]