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

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.