Two-dimensional organic–inorganic hybrid perovskite field-effect transistors with polymers as bottom-gate dielectrics

Abstract

Organic–inorganic hybrid perovskite field effect transistors have attracted considerable attention. However, reports on perovskite transistors utilizing polymer gate dielectrics are relatively rare. In this paper, we have successfully fabricated two-dimensional (2D) perovskite phenylethylammonium tin iodide ((PEA)₂SnI₄) field-effect transistors with poly(vinyl alcohol) (PVA) modified by cross-linking (CL) poly(4-vinylphenol) (PVP) as gate dielectrics (PVA/CL-PVP) in a bottom-gate configuration by a spin coating method. The (PEA)₂SnI₄ thin films are found to possess a highly crystalline layered structure that facilitates lateral charge carrier transport. The PVA/CL-PVP gate dielectric layers not only have uniform and smooth surfaces with high solvent resistance and low polarity, but maintain relatively high capacitances and low leakage currents. The transistors can operate at room temperature in air probably because of the compatibility of the (PEA)₂SnI₄ film and the CL-PVP layer, showing a p-channel characteristic with mobilities of 0.28 cm² V⁻¹ s⁻¹ in the forward gate voltage scan and 0.33 cm² V⁻¹ s⁻¹ in the reverse one. In particular, hysteresis in the devices can be neglected because of suppressed ion migration in the (PEA)₂SnI₄ films, high-quality surfaces of the PVA/CL-PVP layers, and the good compatibility of the perovskite with the polymer gate dielectric. The maximum interface trap densities are estimated to be in the order of 10¹² cm⁻² eV⁻¹, which further confirms that the gate layers offer a high-quality surface and are highly compatible with the (PEA)₂SnI₄ films. Our work can provide a new path to integrate solution-processed perovskites and low-cost and commercially available polymer dielectrics in a bottom-gate transistor structure for future applications in solution-based flexible optoelectronics.