A transparent perovskite thin film transistor

Abstract

The present invention discloses a transparent perovskite thin film transistor, which includes a transparent substrate, a source electrode, a drain electrode, a gate electrode, an insertion layer, a semiconductor layer, and a ferroelectric dielectric layer; the insertion layer is a transparent metal oxide, which is placed between the source and drain electrodes and the semiconductor layer; the ferroelectric dielectric layer is located between the gate electrode and the semiconductor layer; and the semiconductor layer is a transparent perovskite film. A metal oxide film is inserted between the source and drain electrodes and the transparent perovskite film as an electron injection layer to reduce the electron injection barrier and improve the electron injection efficiency; at the same time, a ferroelectric material is used as a dielectric layer to suppress the gate voltage shielding effect caused by the ion migration of the transparent perovskite film; the transparent perovskite thin film transistor prepared on this basis can work at room temperature and has good stability.

Description

Technical Field

[0001] The present invention belongs to the field of organic-inorganic hybrid perovskite organic field effect transistors, and more specifically, relates to the preparation of transparent perovskite thin film transistors. Background Art

[0002] In recent years, organic-inorganic hybrid perovskites have attracted widespread attention as solution-processable semiconductor materials. First-principles theoretical calculations show that the bulk mobility of organic-inorganic hybrid perovskites is as high as 10-100 cm 2 V -1 S -1 Its high carrier mobility and long carrier diffusion length give it good optical and electrical properties. At the same time, this material has a high absorption coefficient, adjustable band gap, and low-temperature solution processing, which makes it have a wide range of application prospects in the field of optoelectronic devices.

[0003] MAPbCl3 is a typical organic-inorganic hybrid perovskite with a wide band gap (2.9eV), does not absorb visible light, and exhibits the properties of a transparent semiconductor. It has a good application prospect in the field of transparent electronic devices. However, due to the ion shielding effect of perovskite materials, transistors made by the commonly used thin film transistor preparation method are difficult to work effectively at room temperature. In addition, for transparent perovskite films such as MAPbCl3 films, the band gap is wide and the gold-semi contact barrier is large, so that electrons cannot be effectively injected into MAPbCl3 for transmission. Therefore, it is difficult to prepare transparent perovskite thin film transistors that can work stably at room temperature. Although there have been previous research reports on single crystal transistors of MAPbCl3 (US10749120B2), single crystal devices cannot be prepared on a large scale and have limited application value. Thin film transistors based on MAPbCl3 are non-single crystal devices, so they can be prepared on a large scale and have high application value. However, there are no relevant reports on MAPbCl3 thin film transistors. Therefore, the development of transparent perovskite thin film transistors that can work normally at room temperature has very important scientific significance and application value. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a transparent perovskite thin film transistor that can work normally at room temperature and a preparation method thereof. That is, a metal oxide film is inserted between the source and drain electrodes and the transparent perovskite film as an electron injection layer to reduce the electron injection barrier and improve the electron injection efficiency; at the same time, a ferroelectric material is used as a dielectric layer to suppress the gate voltage shielding effect caused by the ion migration of the transparent perovskite film; the transparent perovskite thin film transistor prepared on this basis can work at room temperature and has good stability.

[0005] The present invention solves the technical problem by adopting the following technical solution:

[0006] A transparent perovskite thin film transistor, characterized in that it includes a transparent substrate, a source electrode, a drain electrode, a gate electrode, an insertion layer, a semiconductor layer, and a ferroelectric dielectric layer; the insertion layer is a transparent metal oxide and is placed between the source and drain electrodes and the semiconductor layer; the ferroelectric dielectric layer is located between the gate electrode and the semiconductor layer; and the semiconductor layer is a transparent perovskite thin film.

[0007] Furthermore, the metal oxide is tin dioxide, titanium dioxide or zinc oxide.

[0008] Furthermore, the ferroelectric dielectric layer is PVDF-TrFE.

[0009] Furthermore, the perovskite is MAPbCl3.

[0010] Furthermore, the thickness of the ferroelectric dielectric layer is 400-600 nm. If it is too thin, it is easy to cause leakage, and if it is too thick, the capacitance is small, which affects the gate control ability of the device.

[0011] Furthermore, the thickness of the insertion layer is 5-10 nm. If it is too thin, the insertion layer will be discontinuous, and if it is too thick, the quality of the perovskite film grown thereon will be affected.

[0012] The above technical solution has the following technical effects:

[0013] (1) The present invention proposes a new transparent perovskite thin film transistor. Due to the ion shielding effect of perovskite materials, transistors made by conventional thin film transistor preparation methods are difficult to work effectively at room temperature. The present invention uses a ferroelectric dielectric layer to suppress the ion shielding effect, so that the perovskite thin film transistor may work normally at room temperature. In addition, for transparent perovskite films such as MAPbCl3 films, the band gap is wide and the gold-semiconductor contact barrier is large, so that electrons cannot be effectively injected into MAPbCl3 for transmission. Therefore, if no additional measures are taken, the MAPbCl3 thin film transistor that only uses a ferroelectric dielectric layer to suppress the ion shielding effect cannot work normally at room temperature. A metal oxide is used to form an insertion layer between the substrate and the semiconductor layer. The insertion layer can effectively reduce the electron injection barrier and improve the electron injection efficiency, thereby obtaining a MAPbCl3 thin film transistor that can work at room temperature and has good stability.

[0014] (2) The transparent perovskite thin film transistor provided by the present invention has a simple preparation method. The insertion layer, the transparent perovskite layer and the ferroelectric dielectric layer can be formed by spin coating the corresponding solution and then annealing and drying. Without the need for vacuum equipment and other instruments, this substrate processing method that can be implemented using only a coating machine is simpler and suitable for large-scale commercial applications.

[0015] (3) The transparent perovskite thin film transistor provided by the present invention can be prepared on a large area, and therefore has great application potential in the field of transparent display and transparent electronics in the future, and also has broad application prospects in the field of photoelectric detection.

[0016] (4) The preferred metal oxide hydrosol of the present invention is inexpensive and easy to prepare, can be processed by solution method, is easy to operate and is suitable for large-scale processing, thus facilitating its application and promotion to other semiconductor device fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the structure of a transparent perovskite thin film transistor in Example 1 of the present invention;

[0018] Figure 2 A performance output curve diagram of a transparent perovskite thin film transistor in Example 1 of the present invention;

[0019] Figure 3 Performance transfer curve of the transparent perovskite thin film transistor in Example 1 of the present invention. DETAILED DESCRIPTION

[0020] In order to more clearly illustrate the purpose and advantages of the present invention, the present invention is further described in detail with reference to the following embodiments in conjunction with the accompanying drawings. The specific embodiments described below are only used to explain the present invention and are not used to limit the present invention.

[0021] Embodiment 1

[0022] This embodiment takes a top-gate bottom-contact transistor as an example. Other transistors with bottom-gate top-contact, top-gate top-contact, and top-gate bottom-contact can be made by simply changing the positions of corresponding electrodes.

[0023] See also Figure 1 A transparent perovskite thin film transistor includes a transparent substrate (glass), a source electrode (Cr), a drain electrode (Cr), a gate electrode (Al), an insertion layer (SnO2), a semiconductor layer (MAPbCl3), and a ferroelectric dielectric layer (PVDF-TrFE); the thickness of the insertion layer is 10nm, and the thickness of the ferroelectric dielectric layer is 400nm.

[0024] Electrical tests on transparent MAPbCl3 thin film transistors show transistor output and transfer characteristic curves at room temperature, as shown in the attached figure. Figure 2-3 As shown, it can be seen from the transfer characteristic curve and the output characteristic curve that the transistor can operate at room temperature, and the gate voltage can control the current between the source and drain electrodes.

[0025] Embodiment 2

[0026] Accordingly, this embodiment provides a method for preparing a transparent perovskite thin film transistor with a top gate and bottom contact electrode. The method generally comprises the following steps: MACl and PbAc2 are used as perovskite precursor liquid materials, and PVDF-TrFE is used as a dielectric layer material to prepare a transparent perovskite thin film transistor. The specific steps are as follows:

[0027] Step 1: Treat the transparent substrate with photolithography electrodes; select a glass sheet with chrome-gold electrodes as the substrate. First, clean the glass sheet, and then use deionized water, acetone, and isopropanol for ultrasonic cleaning for 1 minute, and then blow dry with an argon gun. Then transfer the glass sheet to the ozone treatment device and treat it for 15 minutes to change the wettability of the glass sheet surface.

[0028] Step 2: Spin-coat the metal oxide solution and anneal at low temperature to form an insertion layer; dilute the 15% tin dioxide aqueous solution with deionized water at a volume ratio of 1:6 and spin-coat it on the ozone-treated substrate at a speed of 500 rpm for 3 seconds, then immediately increase the speed to 3000 rpm for 30 seconds. After the spin coating is completed, immediately place the glass sheet on a hot plate and heat it at 150°C for 30 minutes.

[0029] Step 3: Spin-coat the three-dimensional perovskite solution on the insertion layer and anneal at low temperature to form a three-dimensional perovskite film. Transfer the substrate in step 2 to a glove box filled with argon, dissolve MACl and PbAc2 in DMSO at a molar ratio of 3:1 to obtain a liquid with a concentration of 0.75M. After it is fully dissolved, mix the precursor liquid with DMF at a volume ratio of 4:1 to obtain a MAPbCl3 perovskite precursor liquid. Spin-coat the precursor liquid on the substrate at a speed of 4000rpm for 30s. After the spin coating is completed, immediately transfer the substrate to a hot plate for heating at a heating temperature of 150°C for 2min. A transparent MAPbCl3 film can be obtained.

[0030] Step 4: Spin-coat the ferroelectric solution on the three-dimensional perovskite film and anneal at low temperature to form a ferroelectric dielectric layer. Dissolve 70g / L PVDF-TrFE in n-butyl acetate to obtain a ferroelectric solution, and spin-coat the PVDF-TrFE solution on the perovskite film at a speed of 500rpm for 3s to cover the entire perovskite film, then increase the speed to 4000rpm for 30s. Immediately after the spin coating, transfer the glass substrate after spin coating to a hot stage, and heat it to 90°C for 1h.

[0031] Step 5: Prepare the gate electrode. The glass substrate with the spin-coated insertion layer, perovskite layer and ferroelectric dielectric layer is transferred to a vacuum evaporator to evaporate an aluminum (Al) electrode with a thickness of about 35 nm. After the gate electrode is prepared, a transparent perovskite thin film transistor can be obtained.

Claims

1. A transparent perovskite thin film transistor, characterized in that: Including transparent substrate, source electrode, drain Electrode, gate electrode, insertion layer, semiconductor layer, ferroelectric dielectric layer; the insertion layer is a transparent metal oxide, placed between the source and drain electrodes and the semiconductor layer; the ferroelectric dielectric layer is located between the gate electrode and the semiconductor layer; the semiconductor layer is a transparent perovskite film; the perovskite is MAPbCl3; the thickness of the insertion layer is 5-10nm; the insertion layer serves as an electron injection layer to reduce the electron injection barrier and improve the electron injection efficiency.

2. The transparent perovskite thin film transistor according to claim 1, characterized in that: The metal oxide is tin dioxide, titanium dioxide or zinc oxide.

3. A transparent perovskite thin film transistor according to any one of claims 1-2, characterized in that: The ferroelectric dielectric layer is PVDF-TrFE.

4. A transparent perovskite thin film transistor according to any one of claims 1-2, characterized in that: The thickness of the ferroelectric dielectric layer is 400-600 nm.

Images