Thin film transistor based on two-dimensional organic-inorganic hybrid perovskite

Abstract

Despite the fact that three-dimensional organic-inorganic hybrid perovskite is regarded as a promising material in the field of optoelectronics and microelectronics due to its excellent photoelectric properties, however, the instability under the moisture environment and the gate-voltage screening effect associated with ionic transport are still serious, which restricts the development of perovskite devices. Here in this work, the lead iodide perovskite (PEA)<sub>2</sub>(MA)<i><sub>n–</sub></i><sub>1</sub>Pb<sub>n</sub>I<sub>3<i>n</i>+1</sub> series are successfully prepared by one-step solution method, including pure-two-dimensional (pure-2D), quasi-two-dimensional (quasi-2D) and traditional three-dimensional (3D) perovskite materials. The dimension and microstructure of the perovskites are regulated, and the effects of dimensions on the performance of organic-inorganic hybrid perovskite materials are investigated firstly. The crystallization of the 2D perovskites and 3D perovskite films are observed obviously. Moreover, the surface of pure-2D perovskite film with discoid, regular and micron-sized grains is smoother than that of 3D perovskite film. And also, the unapparent grain boundary is exhibited in the quasi-2D perovskites. A uniform perovskite film with full coverage and inconspicuous grain boundaries facilitates the transmission capacity of the charge carriers in the channel layer due to the reduction of defects caused by the grain boundaries. And benefited from the high-quality films with inconspicuous grain boundary as demonstrated, the quasi-2D hybrid perovskite film exhibits a longer carrier lifetime (<i>τ</i><sub>ns</sub>) than traditional 3D MAPbI<sub>3</sub> perovskite film, revealing that the layered 2D structure is more favorable for carrier transport due to the fewer defects in it. In addition, under the condition of the same environment humidity, the 2D perovskite materials show better moisture stability. Then, to investigate the influences of dimensional structure on the perovskite field-effect devices, we fabricate the bottom-gate and top-contact thin film transistors (TFTs) based on the perovskite materials with different dimensions. As a result, the instability and ion migration effect for each of the devices are suppressed effectively due to the distinct 2D layer-structure and quantum confinement effect, which leads the device performance to be further improved. The device based on quasi-2D (<i>n</i> = 6) channel TFT achieves a hole mobility (<i>μ</i><sub>hole</sub>) of 3.9 cm<sup>2</sup>/(V·s), an on-off current ratio of 10<sup>4</sup> and more, and a 1.85V turn-on voltage of 1.85 V. The first application of quasi-2D organic and inorganic hybrid perovskite materials to thin film transistors provides a new idea for preparing the high-performance and stable thin film transistor devices.