TWI732704B - Perovskite metal-semiconductor-metal photodetector and its manufacturing method - Google Patents

Abstract

The present invention discloses a perovskite metal-semiconductor-metal photodetector and its preparation method, which comprises perovskite crystals (CH ₃ NH ₃ PbBr ₃ ), and is arranged on the surface of the _{perovskite crystals (CH 3} NH _{3 PbBr 3)} Set up a group of electrode groups, the electrode group includes at least two electrodes, each electrode includes an electron transport layer deposited on the surface of the _{perovskite crystal (CH 3} NH ₃ PbBr _{3) with carbon material (C60) and deposited on the electron transport layer} The silver electrode is capable of using the perovskite crystals grown by the reverse temperature crystallization technology as the substrate of the metal-semiconductor-metal photodetector, so it is easy to manufacture and can shorten the manufacturing time cost and improve the sensitivity of the photodetector. And response speed and other characteristics.

Description

Perovskite metal-semiconductor-metal photodetector and its manufacturing method

The present invention relates to a perovskite metal-semiconductor-metal type photodetector and a preparation method thereof, in particular to a preparation technology of an MSM type photodetector by using reverse temperature crystallization technology to grow crystalline perovskite crystals.

According to, perovskite is a material that contains the ABX3 structure type. In this formula, A, B and X represent alkali metal ions or methylamino groups (CH3NH3), metal cations (Pb ₂ , Sn ₂ ), and halogen cations (Cl-, Br-, I-). Compared with organic semiconductor materials, perovskite materials based on organometallic halides have unique optical and electrical properties. As we all know, the exciton binding energy of perovskite materials is extremely small, so most excitons generated after light excitation can be separated to form free electrons and holes at room temperature. In addition, the carrier current of the perovskite has a fast diffusion speed and a long diffusion distance, and the diffusion length of electrons and holes varies with the crystal structure. Compared with MAPbI ₃ , MAPbBr ₃ has a shorter lattice constant, higher cohesive energy, lower phase transition temperature and higher anisotropy. The energy gap is about 2.2eV, and the emission wavelength is green. It has high optical gain and can be used as a gain dielectric layer in laser light. Perovskite materials have been successfully used in light-emitting diodes and solar cells, so perovskite materials have been widely used in various applications in the field of optoelectronic devices.

According to what is known, a metal-semiconductor-metal (MSM) photodetector uses a Schottky barrier between a metal and a semiconductor interface to form a carrier depletion region similar to a PN junction. The photogenerated carriers generated by incident light in the semiconductor are in the depletion region of the reverse Schottky junction under the action of an external electric field Drifting occurs and is quickly collected by the electrodes at both ends of the detector. This structure is equivalent to two back-to-back coplanar Schottky barrier connections. The metal contacts are usually made of cross-stripe shapes directly on the semiconductor surface. Light can be absorbed between the electrode gaps of the metal fingers, and MSM light detection The device avoids the light absorption of the metal layer of the Schottky photodiode in the past, and increases the illumination area of the incident light. At the same time, the MSM structured light detector also has the characteristics of simple structure, small parasitic capacitance, fast response speed, and low production cost. Therefore, it has been widely used in various photon and particle detectors, and therefore has received attention and attention from related industries. Favor.

In addition, most of the conventional crystallization methods for perovskite crystals are typical cooling; or anti-solvent vapor assisted crystallization technology. This crystallization method is time-consuming and requires a long processing time, which causes problems in preparation. Therefore, how to develop a technology to rapidly crystallize and grow perovskite crystals by the inverse temperature crystallization (ITC) method to prepare MSM photodetectors has become a technical issue urgently desired by the relevant industry and academia.

In view of this, the known photodetector and perovskite crystal preparation technology are indeed not perfect, and there is still a need for improvement; the reason is that the inventors have finally developed through continuous efforts in research and development. A set of the present invention which is different from the above-mentioned conventional technology.

The main purpose of the present invention is to provide a perovskite metal-semiconductor-metal photodetector and its preparation method, mainly using perovskite crystals grown and crystallized by reverse temperature crystallization technology as the metal-semiconductor-metal photodetector The base body therefore has the characteristics of being easy to manufacture, shortening the manufacturing time and cost, and improving the sensitivity and response speed of the photodetector. The technical means to achieve the main purpose of the invention includes perovskite crystals (CH ₃ NH ₃ PbBr ₃ ), and a set of electrode groups are arranged on the surface of the perovskite crystals (CH ₃ NH ₃ PbBr _{3 ). The electrode groups include at least two Electrodes, each electrode includes an electron transport layer deposited on the surface of a perovskite crystal (CH 3} NH ₃ PbBr ₃ ) with carbon material (C60) and a silver electrode deposited on the electron transport layer.

1: Metal-semiconductor-metal photodetector

10: Perovskite crystals

10a: Perovskite precursor solution

10b: Perovskite solution

11: Electrode group

110: electron transport layer

111: Silver electrode

20: Metal mask

21: hollow area

30: Petri dish

40: Thermal cycle furnace

50: Ultrasonic Vibrator

Fig. 1 is a schematic diagram of the implementation of the process flow for preparing the MSM photodetector of the present invention.

Figure 2 is a schematic diagram of the volume of _{MAPbBr 3} crystals prepared at different temperatures in the present invention.

Figure 3 is the scanning electron micrograph _{of the CMAPbBr 3} crystals of the present invention at different temperatures.

Figure 4 is a schematic diagram of the luminescence spectra _{of the MAPbBr 3} crystals of the present invention at different temperatures.

Figure 5 is a schematic diagram of the absorption spectra _{of MAPbBr 3} crystals prepared at different temperatures in the present invention.

Figure 6 shows the X-ray diffraction images _{of the MAPbBr 3} crystals of the present invention at different temperatures.

Fig. 7 is a schematic diagram of the current-voltage curve of the _{MAPbBr 3 crystal of the present invention.}

Fig. 8(a) is a schematic diagram of the MSM type photodetector prepared by the present invention; Fig. 8(b) the physical photograph image of the MSM type light prepared by the present invention.

Fig. 9 is a schematic diagram showing the relationship between the current and the wavelength of the MSM photodetector under each bias voltage according to the present invention.

Fig. 10 is a schematic diagram showing the comparison of wavelength and responsivity under different bias voltages according to the present invention.

Figure 11(a) is a schematic diagram of the current-voltage (IV) characteristic comparison of the MSM photodetector of the present invention; Figure 11(b) is the MSM photodetector of the present invention measured under 0.8mW/cm2 of light and at 5V Schematic diagram of the dynamic range.

In order to allow your reviewer to further understand the overall technical features of the present invention and the technical means to achieve the purpose of the invention, specific examples and drawings are used to describe in detail as follows:

Please refer to Fig. 1. The present invention is mainly a manufacturing method of perovskite metal-semiconductor-metal photodetector 1, which includes the following steps:

(a) The perovskite crystal crystallization step is to grow the crystalline perovskite crystal 10 (CH ₃ NH ₃ PbBr ₃ ) by the inverse temperature crystallization technique (ITC).

(b) The electrode deposition step is to _{set a metal mask 20 on the surface of the perovskite crystal 10 (CH 3} NH ₃ PbBr ₃ ). The metal mask 20 has an electrode connected to the metal-semiconductor-metal photodetector 1 The hollow area 21 corresponding to the outline of the group 11, then, carbon material (C60) is deposited on the hollow area 21 to deposit the hollow area on _{the surface of the perovskite crystal 10 (CH 3} NH ₃ PbBr ₃ ) to form a two-electron transport layer 110, and silver (Ag) is deposited on the two electron transport layer 110, and thus the two silver electrodes 111 of the perovskite metal-semiconductor-metal photodetector 1 are prepared.

Specifically, the above-mentioned reverse temperature crystallization technique includes the following steps:

(a1) The preparation step of perovskite solution 10b is to combine 3 to 4 parts by weight of lead bromide (PbBr ₂ ), 1 to 2 parts by weight of perovskite precursor solution 10a (CH ₃ NH ₃ Br ₂ ) and 90 ~110 parts by weight of dimethylformamide solvent (DMF) are uniformly mixed into the perovskite precursor solution 10a (CH ₃ NH ₃ PbBr ₃ ), and the perovskite solution 10b (CH ₃ NH ₃ PbBr ₃ ) is stirred to Until it becomes clarified.

(a2) The perovskite crystallization step is to pour 10-100 parts by weight of acetone, 10-100 parts by weight of alcohol and 10-100 parts by weight of isopropanol into a petri dish 30, and use an ultrasonic oscillator 50 Treat for about 5-15 minutes, then _{pour the perovskite precursor solution 10a (CH 3} NH ₃ PbBr ₃ ) into the petri dish 30 to mix into the perovskite solution 10b (CH ₃ NH ₃ PbBr ₃ ), and then The petri dish 30 is placed in the thermal cycle furnace 40 and heated to 40~80°C, until the perovskite crystal 10 (CH ₃ NH ₃ PbBr ₃ ) grows and crystallizes in the petri dish 30, and then the perovskite crystal 10 (CH ₃ NH ₃ PbBr ₃ ) is taken out.

More specifically, the deposition thickness of the electron transport layer 110 is about 20 nm; the deposition thickness of the silver electrode 111 is about 100 nm. The lead bromide (PbBr ₂ ) is 3.67 parts by weight; the perovskite precursor solution 10a is 1.12 parts by weight; the dimethylformamide solvent (DMF) is 100 parts by weight.

With reference to Figures 1~2, the finished product prepared by the present invention is an MSM photodetector 1. The MSM photodetector 1 includes a rectangular plate of perovskite crystal 10 (CH ₃ NH ₃ PbBr ₃ ), and on the _{surface of the perovskite crystal 10 (CH 3} NH ₃ PbBr ₃ ), a set of electrode groups 11 are arranged. The electrode group 11 includes two electrodes, and each electrode includes a carbon material (C60) deposited on the perovskite The electron transport layer 110 on the surface of the mineral crystal 10 (CH ₃ NH ₃ PbBr ₃ ) and the silver electrode 111 deposited on the electron transport layer 110.

The present invention uses perovskite materials to manufacture various optoelectronic elements, and a large number of related technical researches have been published. The present invention is based on the perovskite crystal 10 (CH ₃ NH ₃ PbBr ₃ ) to deposit the electron transport layer 110 and the silver Ag deposited silver electrode 111 by C60 chemical vapor deposition method to complete the structure of the photodetector 1, the structure performance A (metal-semiconductor-metal) MSM photodetector 1 is produced. First, perovskite crystals are grown by inversion crystallization (ITC) in a preheated thermal cycle furnace 40. The thermal cycle furnace 40 can provide uniform heat to promote the growth of high-quality and large-area crystals. Secondly, the perovskite crystal 10 (CH ₃ NH ₃ PbBr ₃ ) was observed under different growth temperature environments. And through X-ray diffraction (XRD), scanning electron microscope (SEM), ultraviolet visible spectroscopy and photoluminescence (PL) analysis of the electrical properties, optical and morphological characteristics of perovskite crystals. Finally, it is observed that the photodetector 1 of the electrode group 11 formed by the _{perovskite crystal 10 (CH 3} NH ₃ PbBr _{3 ), silver Ag and carbon C60 of the present invention has a responsivity of 24.5 A/W.} Generally speaking, perovskite crystal 10 (CH ₃ NH ₃ PbBr ₃ ) is referred to as MAPbBr ₃ crystal for short.

In a more specific preparation embodiment of the present invention, first, _{the preparation method of CH 3} NH ₃ PbBr ₃ perovskite solution 10b is to add 0.0367g lead bromide PbBr ₂ (99.998%), 0.0112g perovskite in sequence The precursor solution 10aCH ₃ NH ₃ Br ₂ (MAB, 99.9%) and 1 mL of dimethylformamide (DMF, 98%) solvent. Subsequently, the CH ₃ NH ₃ PbBr ₃ perovskite precursor solution 10a was stirred until it became clear. The petri dish 30 was subjected to _{ultrasonic vibration treatment with acetone (CH 3 COCH 3} ), alcohol and isopropanol for about 10 minutes. Then pour the perovskite precursor solution 10a into the petri dish 30 to mix into the perovskite solution 10b, and put it into the thermal cycle furnace 40 at different temperatures, namely: 40°C, 50°C, 60°C, 70 ℃ and 80℃. Among them, it was found that the perovskite crystal 10 (CH ₃ NH ₃ PbBr ₃ ) grew slowly and gradually became larger during the crystal growth process. Finally, a carbon C60 electron transport layer 110 with a thickness of about 20 nm and an Ag silver electrode 111 with a thickness of 100 nm are deposited on the _{perovskite crystal 10 (CH 3} NH ₃ PbBr ₃ ) through thermal evaporation and a metal mask 20 to complete the interdigital The MSM structure of the electrode, wherein Figure 1 shows a schematic diagram of the preparation process of the MSM photodetector 1.

The CH ₃ NH ₃ PbBr ₃ perovskite solution 10b is grown in the thermal cycle furnace 40 until the solution is completely evaporated. As shown in Figure 2, at a growth temperature of ^{40°C (45.5 mm 2} _{), the size of the MAPbBr 3} crystal is the largest. However, the _{crystal area of MAPbBr 3} gradually decreases as the growth temperature increases. At a growth temperature of 80°C (9mm ² _{), the MAPbBr 3} crystal area is the smallest. Therefore, it can be observed that the growth temperature is inversely proportional to the crystal size. The high temperature evaporates and reduces the solution, making it difficult to grow to large-sized crystals.

Figure 2 shows the MAPbBr ₃ crystal diagrams prepared at different temperatures, where each scale unit is 1 mm. Figure 3 shows _{the scanning electron microscope (SEM) images of MAPbBr 3} crystals at 40°C, 50°C, 60°C, 70°C, and 80°C. The crystals obtained at 40 and 80°C contained many smaller and larger particles, respectively. In addition, it is found that as the growth temperature increases, _{the structure of the MAPbBr 3} crystal also becomes larger.

As shown in Figure 4, at 40°C, 50°C, 60°C, 70°C, and 80°C, _{the photoluminescence (PL) emission peaks (ie wavelengths) of MAPbBr 3} crystals are located at 545.6 nm, 543 nm, and 543.6, respectively. nm, 540.6nm and 542.4nm. The peaks are observed to be very close between 540nm and 546nm. The emission peak of PL exhibits a blue shift with the increase of growth temperature. The blue shift can be attributed to the difference in the laser fluence and measurement system and the atmospheric environment used for characterization. The main PL peak (peak A) with the highest energy is located at ~545nm (2.275eV, close to the band gap), and the full width at half maximum (FWHM) is ~30nm. It corresponds to the transition from frequency band to frequency band. The lower energy peak (B peak) has a wide bandwidth of 30 nm at ~560 nm, which is attributed to the emission to the well state (Br vacancies on the crystal surface).

Figure 4 shows the photoluminescence (PL) spectra _{of MAPbBr 3} crystals prepared at different temperatures. As shown in Figure 5, _{the edges of the absorption spectrum of the MAPbBr 3} crystal are located at 537.58nm, 536.83nm, 537.58nm, 539.85nm and 536.03nm at temperatures of 40°C, 50°C, 60°C, 70°C and 80°C, respectively It can be seen that the edge of the absorption spectrum is very large. They are close to each other, and the peak is located between 530nm and 540nm, corresponding to _{the band gap of the MAPbBr 3} crystal single crystal is 2.275eV [35]. Figure 5 shows the absorption spectra _{of MAPbBr 3} crystals prepared at different temperatures.

Figure 6 shows the X-ray diffraction image MAPbBr ₃ crystals at different temperatures MAPbBr ₃ crystal 40 ℃, 50 ℃, 60 ℃ , 70 ℃ and 80 ° C, all of the growth temperature were 14.95 °, 30.15 °, 46.0 ° There is a clear peak at 62.75°. The crystal plane directions corresponding to the cubic crystal structure are (001), (002), (003) and (004), which correspond to high-quality MAPbBr ₃ crystals. When the temperature is at 40°C, a higher peak intensity is observed. On the contrary, at 80°C, the peak intensity is significantly reduced. It can be seen from the SEM image of Figure 2 that the crystallinity and density of the samples prepared at 40°C are the highest. The peak intensity is greater than that of samples prepared at a temperature of 50 to 80°C, because even if the particles are larger, the density is lower. At 40°C, a higher peak intensity is observed. On the contrary, at 80°C, the peak intensity is significantly reduced. It can be seen from the SEM image of Figure 2 that the crystallinity and density of the samples prepared at 40°C are the highest. The peak intensity is greater than that of samples prepared at a temperature of 50 to 80°C, because even if the particles are larger, the density is lower.

Figure 7 shows the current-voltage curve of _{the MAPbBr 3 crystal.} The red, blue and green lines delineate the ohmic area (n=1), the trap-filled area (n>3) and the child area (n=2), respectively. According to Mott-Gurney's law: u=8JDL ³ /9 εε oV ² . Therefore, the carrier mobility of the MAPbBr3 crystal is calculated to be 14.4 cm ² V ^-1 s ^-1 . The calculation formula of the trap density is as follows: n _t =2V _TFL εε _O /eL ² ; the trap density of the _{MAPbBr 3} ^{crystal is 4.7 x 10 10} cm ^-3 .

Figure 7 shows the current-voltage curve of the _{MAPbBr 3 crystal.} As shown in Figure 8(a), the middle layer inserts C60 between the silver (Ag) electrode and the MAPbBr ₃ crystal to prevent the recombination of the two. Figure 8(b) shows a photograph of _{a MAPbBr 3 crystal with an MSM structure.}

Figure 8(a) shows that the MAPbBr ₃ crystal is an MSM photodetector structure. Figure 8(b) is a physical photo _{of the MAPbBr 3 crystal photodetector.} Figure 9 shows the relationship between the current of the photodetector and the wavelength for each bias. Each bias voltage of the device has a high current value in the wavelength range of 400nm to 560nm. However, the current drops significantly in the range of 570nm to 580nm. The absorption edge at around 580nm corresponds to the trap level transition. It is observed that the current rises slightly due to the carrier current relationship from the trap in the band structure, resulting in a wavelength of approximately 300 nm between 600 nm and 640 nm. Figure 9 shows the current and wavelength curves of the MSM-MAPbBr _{3 crystal photodetector.}

Figure 10 shows the wavelength and responsivity under different bias voltages. Under different bias voltages of 15V and a wavelength of 400nm, the responsivity of the module is 13.13 A/W, 14.97 A/W, 17.13 A/W, 19.98 A/W, 22.48 A/W and 24.50 A/W , 16V, 17V, 18V, 19V and 20V. In the range of 400nm to 460nm, the responsivity gradually decreases, and becomes stable in the range of 460nm to 560nm. The responsivity reaches its lowest value at 580nm and slightly increases in the range of 600nm to 640nm. Figure 10 shows the responsivity and wavelength curves of the MSM-MAPbBr3 crystal photodetector. Figure 11(a) shows typical IV characteristics in darkness and light (below 0.8 mW/cm ^2). The bias voltage range of MSM-MAPbBr ₃ crystal photodetector is 0 to 20V. It is about 7.04×10 ^-6 A, and the dark current is about 1.04×10 ^-7 A under a 5V bias. In the research of the present invention, the relatively high dark current is the result of leakage current from the crystal boundary. However, a large contrast between photocurrent and dark current is observed-almost two orders of magnitude. The order of magnitude of the contrast ratio of photocurrent to dark current is similar to other structures in other studies. As shown in Figure 11(b), in order to study the dependence of photocurrent on incident light intensity, the photocurrent density was measured at -5V under different illumination intensities using a 200WXe lamp as the light source. When the intensity of the incident light power is lower than 0.8 mW/cm ² , a linear relationship is observed. However, when the light intensity is higher than 0.8 mW/cm ² , due to balance, the photocurrent saturates the relationship between the generation and recombination of electron-hole pairs.

In the research of the present invention, an improved reverse temperature crystallization method is used to grow MAPbBr ₃ crystals at low temperatures. It was observed that the small single crystals obtained at different growth temperatures became larger as the temperature increased. However, it was found that the crystal size decreased with increasing temperature. Among all the single crystals, the sample prepared at a temperature of 80°C has the smallest size; it is observed that the single crystal prepared at 40°C has the largest size. The XRD pattern shows four obvious peaks, which are related to the high-quality MAPbBr ₃ crystals. The PL emission peak is obtained between 536nm and 538nm. The absorption edge is located at 580nm, which corresponds to the trap level transition. The photocurrent increases slightly from 600nm to 640nm, which is caused by the carrier current relationship of the trap energy level.

The above are only feasible embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent implementation of other changes based on the content, characteristics and spirit of the following claims shall be It is included in the scope of the patent of the present invention. The structural features of the invention specifically defined in the claim are not found in similar articles, and are practical and progressive. They have already met the requirements of a patent for invention. The application is filed in accordance with the law. I would like to request that the Bureau of Junction approve the patent in accordance with the law to protect this The legitimate rights and interests of the applicant.

1: Metal-semiconductor-metal photodetector

10: Perovskite crystals

10a: Perovskite precursor solution

10b: Perovskite solution

11: Electrode group

110: electron transport layer

111: Silver electrode

20: Metal mask

21: hollow area

30: Petri dish

40: Thermal cycle furnace

50: Ultrasonic Vibrator

Claims (5)

A manufacturing method of a perovskite metal-semiconductor-metal photodetector, which comprises: The perovskite crystal crystallization step is to grow crystalline perovskite crystals (CH ₃ NH ₃ PbBr ₃ ) by the inverse temperature crystallization technique (ITC); and The electrode deposition step involves _{arranging a metal mask on the surface of the perovskite crystal (CH 3} NH _{3 PbBr 3} ), the metal mask having a hollow corresponding to the outline of an electrode group of the metal-semiconductor-metal photodetector Area, carbon material (C60) is deposited on the hollow area to deposit at least two electron transport layers on the hollow area on the surface of the _{perovskite crystal (CH 3} NH ₃ PbBr _{3 ), and silver (Ag} ) Deposited on the at least two electron transport layers to prepare at least two silver electrodes of the perovskite metal-semiconductor-metal photodetector. The manufacturing method of the perovskite metal-semiconductor-metal photodetector according to claim 1, wherein the reverse temperature crystallization technology includes the following steps: The preparation step of the perovskite solution is to combine 3 to 4 parts by weight of lead bromide (PbBr ₂ ), 1 to 2 parts by weight of the perovskite precursor solution CH ₃ NH ₃ Br ₂ and 90 to 110 parts by weight of dimethyl The methyl formamide solvent (DMF) is uniformly mixed into a perovskite solution (CH ₃ NH ₃ PbBr ₃ ), and the perovskite precursor solution (CH ₃ NH ₃ PbBr ₃ ) is stirred until it becomes clear; and The perovskite crystallization step is to pour 10-100 parts by weight of acetone, 10-100 parts by weight of alcohol and 10-100 parts by weight of isopropanol into a petri dish, and treat with ultrasonic vibration for about 5-15 minutes , Then pour the perovskite precursor solution (CH ₃ NH ₃ PbBr ₃ ) into the petri dish to mix into the perovskite solution (CH ₃ NH ₃ PbBr ₃ ), and put the petri dish into a hot The circulation furnace is heated to 40-80°C until the perovskite crystal (CH ₃ NH ₃ PbBr ₃ ) grows and crystallizes in the petri dish, and then the perovskite crystal (CH ₃ NH ₃ PbBr ₃ ) is taken out. The manufacturing method of the perovskite metal-semiconductor-metal photodetector according to claim 1, wherein the deposition thickness of the at least two electron transport layers is between 15 and 25 nm; and the deposition thickness of the silver electrode is between 90~110nm. The manufacturing method of the perovskite metal-semiconductor-metal photodetector according to claim 1, wherein the deposition thickness of the at least two electron transport layers is 20 nm; and the deposition thickness of the silver electrode is 100 nm. The manufacturing method of the perovskite metal-semiconductor-metal photodetector according to claim 1, wherein the lead bromide (PbBr ₂ ) is 3.67 parts by weight; the perovskite precursor solution CH ₃ NH ₃ Br ₂ is 1.12 Parts by weight: The dimethylformamide solvent (DMF) is 100 parts by weight.

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