A perovskite thin film transistor and a method for preparing the same

Abstract

The present invention provides a highly efficient and stable perovskite thin film transistor and a preparation method thereof, that is, by depositing a metal oxide insertion layer on a substrate, the orientation of a perovskite film spin-coated thereon can be optimized to obtain a directional and high-quality perovskite film. The field effect transistor prepared on this basis can operate at room temperature and has good stability.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor devices, and mainly relates to a perovskite thin film transistor and a preparation method thereof. Background Art

[0002] Metal halide perovskites have excellent photoelectric properties (high light absorption coefficient (10 5 cm -1 ), long range carrier diffusion length, high defect tolerance and balanced charge transfer, simple and low-cost thin film manufacturing process, and become a research hotspot in the field of optoelectronics. In recent years, perovskite semiconductor materials have attracted close attention from researchers in various fields, and have been deeply studied and widely used in the field of optoelectronic devices, such as solar cells, light-emitting diodes, photodetectors, field-effect transistors, etc. Among them, the energy conversion efficiency of solar cells based on perovskite materials and the external quantum efficiency of light-emitting diodes have reached 25.5% and 21.6% respectively in a short period of time, and their performance can be comparable to or even exceed that of optoelectronic devices based on organic semiconductor materials. However, in comparison, the research enthusiasm for field-effect transistors based on perovskite materials has not been particularly high. As the basic unit of logic operations and drive circuits, field-effect transistors are the cornerstone of the contemporary semiconductor industry. Unlike light-emitting diodes or solar cells, which are two-terminal electrode devices, field-effect transistors are voltage-controlled current devices with three-terminal electrodes. The injection of carriers from the source, the transmission of carriers at the interface between semiconductor materials and dielectrics, and the collection of carriers at the drain are controlled by voltage regulation of the three electrodes of the gate, source and drain.

[0003] However, because perovskite materials have the characteristics of ionic semiconductors, when a certain voltage is applied to the gate electrode of a perovskite field-effect transistor, the ions in the perovskite will migrate under the action of the electric field, forming an ion shielding effect at the interface between the perovskite material and the dielectric, rendering the gate voltage ineffective and thus unable to effectively regulate the transport of carriers in the transistor channel. Since the ion migration effect is strong at room temperature, it is difficult to obtain a perovskite transistor that can work at room temperature.

[0004] However, if the ion shielding effect in perovskite field-effect transistors can be overcome, perovskites will be very suitable for the research and development of transistor devices. For example, metal halide compound perovskites have different dimensions and forms, which can meet different needs in terms of process; in terms of electrical properties, perovskites have very high intrinsic carrier mobility and bipolar characteristics; in terms of optics, perovskites have high light absorption coefficients and photoelectric conversion rates, which are suitable for the research and development of high-performance photosensitive field-effect transistors. Therefore, the development of a new and universal method for preparing perovskite thin-film transistors, and the improvement of the mobility and stability of perovskite thin-film transistors, still has very important scientific research significance and application value. Summary of the invention

[0005] The purpose of the present invention is to provide a highly efficient and stable perovskite thin film transistor and a method for preparing the same, that is, by depositing a metal oxide insertion layer on a substrate, the orientation of the perovskite film spin-coated thereon can be optimized to obtain a directional and high-quality perovskite film. The field effect transistor prepared on this basis can operate at room temperature and has good stability.

[0006] The present invention solves the technical problem, and the technical solution adopted is as follows:

[0007] A perovskite thin film transistor, characterized in that it includes a substrate, a source electrode, a drain electrode, a gate electrode, an insertion layer, and a semiconductor layer, wherein the insertion layer is a metal oxide, and the semiconductor layer is a perovskite thin film.

[0008] Furthermore, the insertion layer is formed by spin coating a metal oxide solution on the substrate and annealing at a low temperature; and the semiconductor layer is formed by spin coating a perovskite solution on the insertion layer and annealing at a low temperature.

[0009] Furthermore, the metal oxide is tin dioxide, titanium dioxide or zinc oxide.

[0010] Furthermore, the perovskite is a two-dimensional perovskite.

[0011] Furthermore, the perovskite film is a directional perovskite film.

[0012] Correspondingly, the present invention provides a method for preparing a perovskite thin film transistor, characterized in that it comprises the following steps:

[0013] A: Preparation of metal oxide and perovskite solutions;

[0014] B: Processing the substrate with photolithographic electrodes and spin coating the metal oxide solution, followed by low temperature annealing to form the insertion layer;

[0015] C: The perovskite solution is spin-coated on the insertion layer and annealed at low temperature to form a perovskite film.

[0016] Furthermore, the metal oxide is tin dioxide, titanium dioxide or zinc oxide.

[0017] Furthermore, the perovskite is a two-dimensional perovskite.

[0018] Compared with the existing technical solutions, the technical solution provided by the present invention can achieve the following beneficial effects:

[0019] (1) The present invention proposes a new perovskite thin film transistor. Due to the ion shielding effect of the perovskite material, the transistor made by directly depositing the perovskite material as the semiconductor layer on the substrate cannot work effectively. However, the present invention uses a metal oxide to form an insertion layer between the substrate and the semiconductor layer. Through the insertion layer, the perovskite layer is oriented and the gate voltage source leakage current is effectively controlled, thereby obtaining a perovskite thin film transistor that can work at room temperature and has good stability.

[0020] (2) The preparation method of the perovskite thin film transistor provided by the present invention is simple, that is, firstly, a tin dioxide (SnO2) solution is spin-coated on the substrate, the substrate is processed by low temperature annealing, and then a perovskite solution is spin-coated thereon, so that a high-quality perovskite thin film with directional arrangement can be simply and quickly prepared. 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.

[0021] (3) The perovskite thin film transistor provided by the present invention can significantly improve the device performance by applying the directional high-quality two-dimensional perovskite film to the transistor, so that it also has broad application prospects in the field of photoelectric detection.

[0022] (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

[0023] Figure 1 Schematic diagram of a bottom-gate bottom-contact perovskite thin film transistor in Example 1 of the present invention;

[0024] Figure 2 (a) A transfer characteristic curve of a bottom-gate bottom-contact perovskite thin film transistor in a saturation region in Example 1 of the present invention;

[0025] Figure 2 (b) Output characteristic curve of the bottom-gate bottom-contact perovskite thin film transistor in the saturation region in Example 1 of the present invention;

[0026] Figure 3 (a) (BA)2(MA) after SnO2 hydrosol treatment in Example 2 of the present invention n-1 Pb n I 3n+1 Schematic diagram of the bottom-gate bottom-contact transistor device structure as a semiconductor layer;

[0027] Figure 3 (b) (BA)2(MA) after SnO2 hydrosol treatment in Example 2 of the present invention n-1 Pb n I 3n+1A transfer characteristic curve diagram of a saturation region of a bottom-gate bottom-contact transistor as a semiconductor layer;

[0028] Figure 4 (a) (BA)2(MA) without SnO2 hydrosol treatment in the comparative example n-1 Pb n I 3n+1 Schematic diagram of the bottom-gate bottom-contact transistor device structure as a semiconductor layer;

[0029] Figure 4 (b) (BA)2(MA) without SnO2 hydrosol treatment in the comparative example n-1 Pb n I 3n+1 A transfer characteristic curve diagram of a saturation region of a bottom-gate bottom-contact transistor as a semiconductor layer; DETAILED DESCRIPTION

[0030] In order to more clearly illustrate the purpose and advantages of the present invention, the following embodiments are combined with the accompanying drawings to further describe the present invention in detail. The specific embodiments described below are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0031] Example 1

[0032] First, a perovskite thin film transistor is provided, taking a bottom-gate top-contact transistor as an example, referring to Figure 1 The transistor includes a substrate (SiO2), a source (Cr), a drain (Cr), a gate (Si), an insertion layer (SnO2), a semiconductor layer ((BA)2(MA) n- 1Pb n I 3n+1 ).

[0033] First, the SiO2 / Si substrate was treated by spin coating SnO2 aqueous sol to obtain the insertion layer, and then (BA)2(MA) was spin coated on it. n-1 Pb n I 3n+1 , making (BA)2(MA) n-1 Pb n I 3n+1 The film changes from random orientation to in-plane orientation. The resulting high-quality oriented perovskite film can be applied to field-effect transistors to obtain (BA)2(MA) that can operate at room temperature and has good stability. n-1 Pb n I 3n+1 Thin film transistor device. Preferably, when (BA)2(MA) n-1 Pb n I 3n+1When the perovskite n value is 4, the device has the highest mobility, which is 2.24×10 -3 cm -2 V -1 s -1 , the transfer characteristic curve and output characteristic curve of the transistor, and the corresponding device saturation region transfer characteristic curve are as follows Figure 2 (a) and Figure 2 (b) As shown in the transfer characteristic curve and the output characteristic curve, it can be seen that the transistor can work at room temperature, and the gate voltage can control the current between the source and drain electrodes.

[0034] Example 2

[0035] Correspondingly, this embodiment provides a method for preparing a perovskite thin film transistor, which generally includes the following steps:

[0036] A: Preparation of metal oxide and perovskite solutions;

[0037] Taking SnO2 as an example, the preparation process of metal oxide solution is explained: first, take out the SnO2 hydrosol in the refrigerator, dilute it with deionized water to a concentration of 2.67%, and then use a water filter head to filter the solution to remove impurities to obtain SnO2 solution and store it in the refrigerator. When using, take out the solution and restore it to room temperature.

[0038] Based on two-dimensional perovskite (BA)2(MA) n-1 Pb n I 3n+1 Taking the preparation of perovskite solution as an example, different average number of layers <n>The preparation of the two-dimensional perovskite precursor solution has different raw material ratios, such as <n>=4, BA:MAI:PbI2=2:(n-1):n=2:3:4 (molar ratio of each material), the specific details are as follows:

[0039] 1) Dissolve PbI2 and MAI: Weigh 500 mg of PbI2 and MAI respectively, and dissolve them in 1 mL of DMF. The PbI2 solution needs to be heated and stirred at 70°C for 12 hours.

[0040] 2) Massage and mix BA (740 mg / mL) and the prepared PbI2 and MAI solutions in proportion, heat at 70°C until they are evenly mixed, and then cool to room temperature for use.

[0041] B: Processing the substrate with photolithographic electrodes and spin coating the metal oxide solution, followed by low temperature annealing to form the insertion layer;

[0042] Taking SiO2 / Si substrate with source and drain electrodes (Cr) and SnO2 as metal oxide as an example, the specific steps are as follows:

[0043] 1) The SiO2 / Si substrate was cleaned with deionized water, acetone, deionized water, and isopropanol ultrasonically for 3 minutes in sequence, and then dried with an argon gun. The SiO2 / Si substrate was then transferred to an ozone treatment device for 15 minutes to change the wettability of the SiO2 / Si substrate surface;

[0044] 2) In a fume hood, take the diluted SnO2 solution and spin-coat it on the treated SiO2 / Si substrate at a speed of 3000 rpm. After the spin coating process, the substrate is immediately transferred to a heating table for annealing at a temperature of 150°C for 30 minutes, thereby forming a SnO2 film; the SiO2 / Si substrate treatment process is now completed. The SnO2 film is characterized by atomic force microscopy, and the RMS value of the SnO2 film is 2.052nm, indicating that the film surface is flat, which is conducive to the subsequent deposition of perovskite film.

[0045] C: The perovskite solution is spin-coated on the insertion layer and annealed at low temperature to form a perovskite film.

[0046] Then Si / SiO2 / Cr / SnO2 was treated with ozone for 15 min again. After the treatment, it was transferred to a glove box filled with argon and spin-coated with the prepared (BA)2(MA) n-1 Pb n I 3n+1 The solution is then annealed at 100°C to form a semiconductor layer, and the Figure 3 (a) Perovskite thin film transistor shown.

[0047] A high-precision digital source meter (Keysight B2912A) was used to test the transfer characteristic curve and output characteristic curve of the transistor. The corresponding device saturation region transfer characteristic curve is shown in Figure 3 (b) as shown.

[0048] This embodiment illustrates that the method provided by the present invention can significantly improve the performance of perovskite transistor devices.

[0049] Comparative Example 1

[0050] The transistor with bottom gate and top contact without insertion layer is prepared by the same method as in Example 2, except that the SnO2 solution is not spin-coated, and the perovskite solution is directly spin-coated on the substrate with source and drain electrodes, and low-temperature annealing is performed to form a perovskite film. Figure 4 The transistor shown in (a) is tested using a high-precision digital source meter (Keysight B2912A) to measure the transfer characteristic curve and output characteristic curve of the transistor. The corresponding device saturation region transfer characteristic curve is shown in Figure 4 As shown in (b), the device cannot work properly and cannot achieve gate voltage control of the current between the source and drain electrodes.< / n> < / n>

Claims

1. A perovskite thin film transistor, characterized in that: It includes a substrate, a source electrode, a drain electrode, a gate electrode, an insertion layer, and a semiconductor layer, wherein the insertion layer is a metal oxide, and the semiconductor layer is a perovskite film; the insertion layer is formed by spin-coating a metal oxide solution on the substrate and annealing at a low temperature; the semiconductor layer is formed by spin-coating a perovskite solution on the insertion layer and annealing at a low temperature; the perovskite film is directional arranged by the insertion layer; the metal oxide is tin dioxide, titanium dioxide or zinc oxide; the perovskite is a two-dimensional perovskite; and the transistor is a bottom-gate structure.

2. A method for preparing a perovskite thin film transistor, characterized in that: The following steps are involved: A: Preparation of metal oxide and perovskite solutions; B: Processing the substrate with photolithographic electrodes and spin coating the metal oxide solution, followed by low temperature annealing to form the insertion layer; C: Spin coating the perovskite solution on the insertion layer and annealing at low temperature to form a perovskite film; The perovskite film is a semiconductor layer, and the insertion layer enables the perovskite film to be oriented; The metal oxide is tin dioxide, titanium dioxide or zinc oxide; the perovskite is a two-dimensional perovskite; and the transistor is a bottom-gate structure.

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