CN114551724B - Broadband and narrowband integrated multiplication type perovskite photoelectric detector - Google Patents

Abstract

The invention belongs to the technical field of narrow-band and wide-band perovskite photoelectric detection, and particularly provides a broadband and narrow-band integrated multiplication type perovskite photoelectric detector. The perovskite monocrystal is used as an active layer, and the polymer is covered on the surface of the perovskite monocrystal to be used as an isolation layer and a hole transport layer. Light is incident from the direction of ITO, under reverse bias, the short wavelength generates photon-generated carriers in the perovskite single crystal with the thickness of about 16 mu m and is subjected to recombination quenching in the perovskite single crystal, and meanwhile, holes are injected by the induction of a silver electrode, so that narrow-band response is shown near the absorption band edge of the perovskite. Meanwhile, under forward bias, photon-generated carriers excited by short-wavelength light in the perovskite are gathered at the interface of the hole transport layer and the perovskite, and holes are injected from ITO under the direction of an external electric field under the forward bias, so that the broadband multiplication photodetector with the halide perovskite in the absorption wavelength range is formed.

Description

A multiplied perovskite photodetector integrating broadband and narrowband

technical field

The invention belongs to the technical field of narrow-band and broadband perovskite photoelectric detection, and relates to a manufacturing method of a narrow-band perovskite multiplication type photodetector under a reverse bias voltage and a wide-band perovskite multiplication type photodetector under a forward bias voltage and its integrated application.

Background technique

In recent years, organic-inorganic perovskites have attracted much attention due to their excellent properties such as high light absorption, long carrier lifetime, and long diffusion length. These properties suggest that organic-inorganic perovskites are excellent materials for photodetector applications with low cost and ease of preparation. Perovskite photodetectors are optoelectronic devices that convert optical signals into electrical signals by using perovskite as the active layer. According to different wavelength response bandwidths, photodetectors can be roughly divided into broadband and narrowband photodetectors. Broadband detectors are mainly used in related fields such as cameras, industrial cameras, and autonomous driving; narrowband detectors are mainly used in monochromatic light detection applications such as biomedical sensing, security systems, and optical communications. In the same device, through the change of photoelectric conditions, the detection performance of broadband and narrowband can be integrated at the same time, and the development of a new, multi-functional, integrated photoelectric detection system has important application value and is an important development direction of a new generation of sensors.

Common approaches to realize narrow-band detectors are as follows: (1) Combining broadband photodetectors with band-pass filters (2) Using narrow-band absorbing materials as active layers (3) Intentionally enhancing specific wavelength absorption through plasmonic effects . (4) A narrow-band mechanism for charge collection via quenching of short-wavelength photogenerated carriers. It is worth noting that the first three methods for realizing narrowband detection cannot realize narrowband response and wideband detection at the same time in the same device structure. Existing devices that have both broadband and narrowband responses in the same device mostly achieve narrowband response by quenching the charge collection of short-wavelength photogenerated carriers, and obtain broadband response by changing the light incident direction, thereby realizing the coexistence of broadband and narrowband Photodetector. However, in practical applications, we need a simpler method to control the broadband and narrowband responses in the same device, which makes the multiplied photodetector realized by changing the direction of the externally applied bias voltage have great application prospects.

Contents of the invention

The primary purpose of the present invention is to provide a multiplied perovskite photodetector integrating broadband and narrowband.

Another object of the present invention is to provide a method for preparing the multiplied perovskite photodetector integrated with broadband and narrowband. The invention adopts the perovskite single crystal as the active layer, and the polymer is covered on the surface of the perovskite single crystal as the isolation layer and the hole transport layer. Light is incident from the direction of ITO. Under reverse bias, short wavelengths generate photogenerated carriers in the perovskite single crystal with a thickness of about 16 μm and recombine and quench them inside. At the same time, holes are induced and injected by the silver electrode, so the perovskite Near the edge of the ore absorption band is a narrow band response. At the same time, under forward bias, the photogenerated carriers excited by short-wavelength light in the perovskite gather at the interface between the hole transport layer and the perovskite, and the direction of the applied electric field under forward bias induces the holes from ITO implantation to form broadband multiplied photodetectors in the halide perovskite absorption wavelength range.

In view of the characteristics of forward conduction and reverse cutoff of rectifier diodes, in order to obtain better conductivity under both forward bias and reverse bias, a bidirectional conduction structure with two hole transport layers sandwiching the photoactive layer was designed. , choose the appropriate frontier orbital energy level of the transport layer, and a high-performance photodetector can be obtained under bidirectional bias.

The purpose of the present invention is achieved by the following scheme: a multiplication type perovskite photodetector integrated with broadband and narrowband, including: anode electrode, hole transport layer I, perovskite layer, hole transport layer II, cathode interface layer and the cathode electrode; the device structure is arranged in the above sequence from the anode electrode to the cathode electrode from left to right.

The present invention is different from the common vertical 7-layer structure, in which the perovskite layer is composed of a small halogen perovskite single crystal, and the perovskite single crystal is covered and wrapped by the electron transport layer I, and then spin-coated with electrons in turn. Transport layer II and evaporation electrodes.

Preferably, the material of the cathode is silver, gold, platinum or titanium.

Preferably, the thickness of the cathode electrode is about 0.08-0.2 μm, preferably 0.1 μm.

Preferably, the hole transport layer I is made of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (ie PTAA). The thickness of the hole transport layer I is 0.003-0.008 μm.

Preferably, the perovskite layer is CH ₃ NH ₃ PbBr ₃ .

Preferably, the thickness of the perovskite layer is about 10-17 μm.

As a preference, the material of the hole transport layer II is poly[(4,7-bis(4-(2-ethylhexyl)thiophen-2-yl)-5,6-difluorobenzo[C][ 1,2,5] Thiadiazole-5,5-diyl) ([2,2'] bithiophene-5,5'-diyl)] (ie PffBT4T-2OD).

Preferably, the hole transport layer II has a thickness of about 0.5-0.7 μm.

Preferably, the cathode interface layer adopts poly[(9,9-di(3'-(N,N-dimethylamino)propyl)fluorenyl-2,7-diyl)-ALT-(9,9 -Di-n-octylfluorenyl 2,7-diyl)]-bromine (ie PFN-Br), with a thickness of about 0.005-0.008 μm.

Preferably, the material of the anode is a transparent conductive substrate, including ITO, with a thickness of about 0.13-0.14 μm.

The present invention provides a kind of preparation method of multiplication type perovskite photodetector integrated with broadband and narrowband, specifically as follows:

Step 1, preparing a hole transport layer I on the transparent electrode;

Step 2, growing perovskite on the hole transport layer I as the active layer;

Step 3, preparing a hole transport layer II on the active layer;

Step 4, preparing a cathode interface layer on the hole transport layer II;

Step 5, preparing a metal electrode on the cathode interface layer.

The preparation method of the multiplied perovskite photodetector integrated with the above-mentioned broadband and narrowband is more specifically as follows:

Step 1. Spin-coat PTAA on the transparent anode, and anneal at 70-90°C for 15-20 minutes to form a dense PTAA film to obtain the hole transport layer I;

Step 2. On the hole transport layer I, drop the perovskite precursor solution, put two pieces of transparent ITO spin-coated with PTAA together to form a semi-closed space, and use the method of temperature inversion crystallization from 40 ° C to Slowly increase the temperature at 80°C to grow a perovskite single crystal, and then form a discontinuous perovskite single crystal film to obtain a perovskite layer;

Step 3. Apply PffBT4T-2OD thickly to the perovskite discontinuous single crystal film and spread it evenly to wait for the solvent of the drip-coated polymer to evaporate and dry, then anneal at 70-90°C for 15-20 Minutes, the hole transport layer II was prepared;

Step 4: Spin-coat PFN-Br on the hole transport layer II to prepare a cathode interface layer, and then vapor-deposit silver as a cathode.

A method for obtaining a broadband response or a narrowband response, specifically, applying a negative bias voltage to the above-mentioned detector to obtain a narrowband response or applying a positive bias voltage to obtain a broadband response.

Preferably, the negative bias voltage is -1-4V, and the positive bias voltage is 1-4V.

The beneficial effects that the present invention has are as follows:

The present invention adopts two kinds of different hole transport layers to be placed on both sides of the perovskite layer respectively, wherein PffBT4T-2OD has an energy level structure (its HOMO and LOMO) which is _extremely consistent with MAPbBr as the hole transport layer II material close to the metal electrode. The energy levels are -3.7 and -5.4), and has excellent carrier transport characteristics, so that under negative bias, the carriers excited by short-wavelength photons are depleted in the perovskite layer, and the remaining wavelengths are in the Photons near the perovskite absorption band edge can successfully excite electrons and holes without recombination at the interface inside the perovskite. Among them, PffBT4T-2OD is used as a hole transport layer, so that electrons accumulate at the interface between PffBT4T-2OD and the perovskite single crystal, and holes are induced to tunnel and inject from the Ag electrode, thereby obtaining a multiplied narrow-band response. Under positive bias, due to the direction of the applied external electric field, the electrons and holes excited by the incident short-wavelength photons are not recombined and quenched in the perovskite crystal. The interfacial aggregation between perovskite and PTAA induces hole injection from the ITO direction, resulting in a good broadband response with high EQE multiplication.

The present invention adopts a small piece of perovskite single crystal thin film and covers it with PffBT4T-2OD thick coating to form a thick film wrapped discontinuous perovskite single crystal thin film, which plays a role in transporting holes and isolating the electron transport layer and metal electrode of subsequent spin coating To ensure that the transparent electrode is separated from the metal electrode, and since the evaporation area of the metal electrode is larger than the area of the perovskite single crystal, this provides a good hole injection site for the multiplication of the device, thereby obtaining a multiplication photodetection device.

The invention controls the wide and narrow band response of the photodetector by changing the direction of the applied voltage, and under the external applied bias voltage in different directions, the external quantum efficiency (EQE) also increases correspondingly with the increase of the applied bias voltage. At -4V, its external quantum efficiency is 344% at 550nm green light, its responsivity is 1.53A/W, and it has a high detection rate of 1.35× ¹⁰¹¹ . It has a high external quantum efficiency in the wide range of visible light, the full width at half maximum of the response is greater than 220nm, and the peak EQE at 370nm is 949%, the responsivity is 2.98A/W, and the detection rate is 9.81×10 ¹⁰ Jones .

The present invention does not require a filter layer or change the direction of illumination, and can obtain control and select wideband or narrowband response only by changing the direction of voltage applied by an external circuit.

Description of drawings

Fig. 1 is the structure of the perovskite multiplied photodetector device of the present invention.

Fig. 2 is a schematic diagram of the preparation process of the photodetector of the present invention.

Fig. 3 is an energy level diagram of the photodetector of the present invention; wherein (a) is applied with a reverse bias voltage, and (b) is applied with a forward bias voltage.

Fig. 4 is the external quantum efficiency curve of the same device in embodiment 1 from -4 volts to 4 volts under the incident bias from the direction of the transparent electrode to 4 volts; where (a) is for applying a reverse bias, (b) is for applying a forward bias .

FIG. 5 is a multifunctional detection array prototype device prepared based on the broadband and narrowband integrated multiplied perovskite photodetector obtained in Example 1.

Detailed ways

The present invention will be further explained below in conjunction with the accompanying drawings.

Example 1

As shown in Figure 1, a multiplication perovskite photodetector with both broadband and narrowband coexistence includes a transparent anode electrode (ITO, ie indium tin oxide) 1, a hole transport layer I (PTAA, ie [double (4- Phenyl) (2,4,6-trimethylphenyl) amine]) 2, perovskite layer 3, hole transport layer Ⅱ (PffBT4T-2OD, poly[(4,7-bis(4-(2 -Ethylhexyl)thiophen-2-yl)-5,6-difluorobenzo[C][1,2,5]thiadiazole-5,5-diyl)([2,2']bithiophene -5,5'-diyl)])4, cathode interface layer (PFN-Br, poly[(9,9-bis(3'-(N,N-dimethylamino)propyl)fluorenyl-2 ,7-diyl)-ALT-(9,9-di-n-octylfluorenyl2,7-diyl)]-bromo)5 and cathode electrode (Ag)6.

In the present invention, two hole transport layers of different materials are placed on both sides of the perovskite active layer, namely the hole transport layer I2 and the hole transport layer II3. As shown in Figure 3, PffBT4T-2OD, as the hole transport layer II material close to the metal electrode, has an energy level structure that is extremely consistent with MAPbBr3. When light is incident from the ITO transparent electrode, under negative bias, the short wavelength The carriers excited by photons are depleted in the perovskite layer, and the photons with remaining wavelengths near the perovskite absorption band edge can successfully excite electrons and holes without recombination at the interface inside the perovskite. Among them, PffBT4T-2OD is used as a hole transport layer, so that electrons accumulate at the interface between PffBT4T-2OD and the perovskite single crystal, and induce holes to be tunneled and injected from the Ag electrode and collected by the electrode, thereby obtaining a multiplied narrow-band response. . Under positive bias, due to the direction of the applied external electric field, the electrons and holes excited by the incident short-wavelength photons are not recombined and quenched in the perovskite crystal. The interfacial aggregation between perovskite and PTAA induces hole injection from the ITO direction, resulting in a good broadband response with high EQE multiplication.

As shown in Figure 2, by changing the direction of the bias voltage to realize the preparation method of the multiplied photodetector with coexistence of narrow band and broadband, the specific steps are as follows:

Step 1. The transparent anode ITO is ultrasonically cleaned with deionized water, acetone and isopropanol and then dried. Spin-coat PTAA on the ITO as the hole transport layer I at a spin-coating rate of 2000 rpm for 40 seconds, and use Anneal at 80 degrees for 15-20 minutes to form a dense PTAA film with a thickness of about 3-8nm. Its hydrophobicity can help the perovskite precursor solution spread evenly on the ITO.

Step 2. On the hole transport layer I, drop the perovskite precursor solution, and put two pieces of transparent ITO spin-coated with PTAA together to form a semi-closed space. Use the method of temperature inversion crystallization from 40 degrees to 80 degrees. Slowly increase the temperature to grow perovskite single crystals, and then form perovskite discontinuous single crystal films.

Step 3. Prepare the hole transport layer II on the discontinuous perovskite thin film single crystal by thick coating PffBT4T-2OD, drop-coat PffBT4T-2OD and spread it evenly until the solvent of the drip-coated polymer evaporates to form a thickness of about 300nm thick film, then annealed at 80 degrees for 15-20 minutes.

Step 4: Spin-coat PFN-Br with a thickness of 5-8 nm on the hole transport layer II at 2000 rpm for 40 seconds, and then vapor-deposit 100 nm of silver as a cathode.

As shown in Figure 4, according to the above preparation method, based on the 15 micron thick CH ₃ NH ₃ PbBr ₃ as the active layer, the light is incident from the ITO side at reverse bias -1, -2, -3, -4, forward bias External quantum efficiency spectral curves of the detector at voltages 1V, 2V, 3V, 4V and 0V, where the curves in Figure 4(a) correspond to -4V, -3V, -2V, -1V and 0V from top to bottom. Figure 4(b) curves correspond to 4V, 3V, 2V, 1V and 0V from top to bottom. When the applied bias voltage is -4V, the EQE at 550nm green light is 344%, the half-peak width is less than 20nm, the responsivity is 1.53A/W, and it has a narrow-band spectral response with a high detection rate of 1.35×10 ¹¹ . When the applied bias voltage is 4v, it has a high external quantum efficiency in the wide range of 320nm-550nm ultraviolet to visible light, and the full width at half maximum of the response is greater than 220nm, and the peak EQE at 370nm is 949%, and the responsivity is 2.98 A/W, and a broadband response with a detection rate of 9.81×10 ¹⁰ Jones.

Application Example 1

The multifunctional detection array prototype device based on the multiplication type perovskite photodetector integrated with broadband and narrowband, uses the multiplication type perovskite photodetector device described in Embodiment 1 as the pixel element of CCD, including: lens 1, The color filter 2 and the wideband and narrowband integrated multiplication type photodetector array 3 of the present invention are shown in FIG. 5 .

The broadband and narrowband integrated multiplication type photodetector is composed of a transparent electrode, a hole transport layer I, a perovskite array layer, a hole transport layer II, a cathode interface layer and a metal electrode.

Specifically, when the light enters from the lens direction, the light passes through the color separation filter (red (R), green (G), blue (B)) as a filter layer to make the multi-band light into three different bands of light, Then the perovskite photodetector is fired from the transparent anode. When a positive bias is applied externally, the perovskite photodetector of the present invention exhibits a broadband response, can detect light in different bands, and quickly converts the optical signal into an electrical signal and transmits the signal to the image processing chip to achieve color imaging applications. Under the externally applied reverse bias voltage, the photodetector of the present invention has narrow-band response, can quickly detect fixed monochromatic light signals, saves the algorithm analysis for complex pictures, and greatly speeds up the response speed of the system. This has great application prospects in indicator lights, semaphores, optical fiber signal communication, and automatic driving. In the process of continuous imaging, the use of forward bias and reverse bias alternate imaging can effectively solve the common problem of charge storage and the "ghost" problem of historical image retention caused by electrical signal storage.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (10)

1. A multiplying perovskite photodetector integrated with broadband and narrowband, characterized in that it comprises: an anode electrode, a hole transport layer I, a perovskite layer, a hole transport layer II, a cathode interface layer and a cathode electrode; The device structure is arranged in the above sequence from the anode electrode to the cathode electrode from left to right. 2. The photodetector according to claim 1, characterized in that: the material of the hole transport layer I is poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine ]; The thickness of the hole transport layer I is 0.003-0.008 μm. 3 . The photodetector according to claim 1 , wherein the material used for the perovskite layer is CH ₃ NH ₃ PbBr ₃ ; and the thickness of the perovskite layer is 10-17 μm. 4. The photodetector according to claim 1, characterized in that: the material used in the hole transport layer II is poly[(4,7-bis(4-(2-ethylhexyl)thiophene-2- base)-5,6-difluorobenzo[C][1,2,5]thiadiazole-5,5-diyl)([2,2']bithiophene-5,5'-diyl) ]; the thickness of the hole transport layer II is 0.5-0.7 μm. 5. The photodetector according to claim 1, characterized in that: the cathode interface layer adopts poly[(9,9-bis(3'-(N,N-dimethylamino)propyl) Fluorenyl-2,7-diyl)-ALT-(9,9-di-n-octylfluorenyl 2,7-diyl)]-bromine; the thickness of the cathode interface layer is 0.005-0.008 μm. 6 . The photodetector according to claim 1 , wherein the cathode is made of silver with a thickness of 0.05-0.3 μm; the anode is made of a transparent conductive substrate with a thickness of 0.13-0.14 μm. 7. the preparation method of the multiplying type perovskite photodetector described in any one of claim 1～6 integrated broadband and narrow band, it is characterized in that being specific as follows: Step 1, preparing a hole transport layer I on the transparent electrode; Step 2, growing perovskite on the hole transport layer I as the active layer; Step 3, preparing a hole transport layer II on the active layer; Step 4, preparing a cathode interface layer on the hole transport layer II; Step 5, preparing a metal electrode on the cathode interface layer. 8. the preparation method of the multiplication type perovskite photodetector of broadband and narrowband integration according to claim 7, is characterized in that being as follows: Step 1. Spin-coat poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] on the transparent anode, and anneal at 70-90°C for 15-20 minutes to form a dense poly[ Two (4-phenyl) (2,4,6-trimethylphenyl) amine] film, obtain hole transport layer I; Step 2. On the hole transport layer I, drip the perovskite precursor solution, spin-coat the two sheets with poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] The transparent ITO is combined to form a semi-closed space, and the perovskite single crystal is grown by slowly increasing the temperature from 40°C to 80°C by the method of inversion crystallization, and then forms a discontinuous perovskite single crystal film to obtain a perovskite layer; Step three, using thick coating poly[(4,7-bis(4-(2-ethylhexyl)thiophen-2-yl)-5,6-difluorobenzo [C][1,2,5]thiadiazole-5,5-diyl)([2,2']bithiophene-5,5'-diyl)] in perovskite discontinuous single crystal Drop-coating poly[(4,7-bis(4-(2-ethylhexyl)thiophen-2-yl)-5,6-difluorobenzo[C][1,2,5]thiadiazole on film -5,5-diyl)([2,2']bithiophene-5,5'-diyl)] and spread evenly to wait for the solvent of the drop-coated polymer to evaporate, and then anneal at 70~90°C for 15- After 20 minutes, the hole transport layer II was prepared; Step 4: Spin-coat poly[(9,9-bis(3'-(N,N-dimethylamino)propyl)fluorenyl-2,7-diyl)-ALT-( 9,9-Di-n-octylfluorenyl 2,7-diyl)]-bromine to prepare the cathode interface layer, and then vapor-deposit silver as the cathode. 9. A method for obtaining a broadband response or a narrowband response, characterized in that a negative bias voltage is applied to the detector according to any one of claims 1 to 6 to obtain a narrowband response or a positive bias voltage is applied to obtain a broadband response. 10. The method according to claim 9, wherein the negative bias voltage is -1-4V, and the positive bias voltage is 1-4V.

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