Organic photoelectric detector based on quantum dot active layer processing strategy and preparation method thereof

Abstract

The invention discloses an organic photoelectric detector based on a quantum dot active layer processing strategy and a preparation method thereof, and belongs to the field of photoelectric detection. According to the detector, an aluminum-based template with a nanometer hole structure is introduced, the aluminum-based template is pressed on a quantum dot layer in a covering mode through a certain pressure so that the surface appearance of the quantum dot layer can be changed, the contact area between the quantum dot layer and organic matter can be increased, and the detector structurally comprises a glass substrate layer, an ITO electrode layer, a ZnO layer, a CQD layer, a P3HT layer, a MoO3 layer and an Ag electrode layer from bottom to top. According to the invention, a plurality of holes are pressed in the surface of the quantum dot layer from outside to inside, so that the P3HT layer can enter the holes in the surface of the quantum dot layer, thereby increasing the contact area between the quantum dot layer and an organic matter, accelerating the separation of photon-generated carriers, and improving the response speed of a photoelectric device.

Description

Technical Field

[0001] The present invention belongs to the field of photoelectric detection, and in particular relates to an organic photoelectric detector based on a quantum dot active layer processing strategy and a preparation method thereof. Background Art

[0002] Photodetectors play an extremely important role in daily life and production. Whether used for photoelectric imaging or optical communication, the function of photodetectors is to convert the collected optical signals into electrical signals that can be processed by standard electronic devices. Infrared photodetectors have been the focus of international research due to their wide applications in biological imaging, thermal imaging, health monitoring, night vision and optical communications. Among semiconductor optoelectronic devices, silicon is the most commonly used material. Silicon-based photodetectors have a fairly mature process on existing complementary metal oxide semiconductor imaging devices, which makes silicon-based optoelectronic devices scalable while miniaturizing, greatly reducing manufacturing costs. At the same time, they have the characteristics of low power consumption and high efficiency. As the main force of visible light and near-infrared photodetection, they are widely used in aerospace, security inspection, medical treatment, monitoring and other fields. However, since silicon is an indirect bandgap semiconductor material, its bandgap is about 1.12 eV (the corresponding absorption cutoff wavelength is about 1.1μm), which limits the detection of silicon in the near-infrared band. In order to expand the response band of photodetectors, semiconductor materials with smaller band gaps are often needed, such as epitaxially grown HgCdTe, InGaAs, indium antimonide (InSb), and type II superlattices. These semiconductor materials can well cover the near-infrared to far-infrared spectral range that silicon cannot detect, but such materials require the use of equipment such as molecular beam epitaxy (MBE) or metal organic chemical vapor deposition (MOCVD), which greatly increases the manufacturing cost; secondly, infrared optoelectronic devices made of these materials generally need to work at low temperatures to maintain low noise and high sensitivity. At the same time, these traditional infrared semiconductor materials are difficult to be compatible with silicon based on mature CMOS processes due to the problem of lattice mismatch, which makes it difficult to integrate them at high density. Traditional photoelectric detection materials have been difficult to meet the requirements of silicon process compatibility, low manufacturing cost, and no need for low-temperature operation. Research based on new mechanisms and new materials is a technical problem that needs to be overcome in the development of new high-performance infrared optoelectronic devices.

[0003] In recent years, the development of materials science and technology and the emergence of many new low-dimensional quantum materials have provided more options for the development of photoelectric detection technology. Quantum dots have narrow emission spectra, very high detection sensitivity and tunable absorption peaks. In particular, quantum dots made from traditional narrow bandgap semiconductors show excellent performance in the near-infrared band to short-wave infrared range (750nm–3500nm), such as lead sulfide (PbS), lead selenide (PbSe), lead telluride (PbTe), mercury telluride (HgTe), indium arsenide (InAs) and indium telluride (InSb). Inorganic quantum dots have developed rapidly in recent years due to their generally high light absorption, high detection efficiency in the infrared band, low cost, easy preparation and no restrictions on substrate materials. Compared with other material technologies, quantum dots are very competitive in the development of new infrared optoelectronic devices.

[0004] At present, infrared quantum dot photodetectors use quantum dot materials to prepare colloidal films as infrared sensitive layers. Quantum dot materials absorb incident light, generate photogenerated carriers, form photocurrent, and realize photodetection. Due to the small contact area between the quantum dot layer and organic matter, the migration rate of photogenerated carriers is limited, which affects the generation of photogenerated current, thereby affecting the response time and responsivity of the photodetector. Summary of the invention

[0005] The purpose of the present invention is to solve the problems of small contact area between the quantum dot layer and organic matter, limited photogenerated carrier migration rate, long response time and low responsivity of the photodetector in traditional organic photodetectors. An organic photodetector based on a quantum dot active layer processing strategy and a preparation method thereof are proposed.

[0006] The present invention uses a quantum dot layer as a photosensitive layer to absorb light and generate electron-hole pairs. By introducing an aluminum-based template with a nano-hole structure, it is pressed on the quantum dot layer with a certain pressure to form multiple holes on the top of the quantum dot layer to change the surface morphology of the quantum dot layer and increase the contact area between the quantum dot layer and the organic layer. The P3HT layer is deposited in the holes on the top of the quantum dot layer, and the contact area with the quantum dot layer is increased, the migration rate of photogenerated carriers is increased, and the response performance of the photodetector is improved.

[0007] Therefore, the technical solution of the present invention is an organic photodetector based on a quantum dot active layer processing strategy, characterized in that the structure of the organic photodetector includes, from bottom to top, a glass substrate layer, an ITO electrode layer, a ZnO layer, a CQD layer, a P3HT layer, a MoO3 layer, and an Ag electrode layer; the ITO electrode layer represents an indium tin oxide electrode layer, the CQD layer represents a colloidal quantum dot layer, and the P3HT layer is a polymer layer of 3-hexylthiophene; the CQD layer is provided with vertical holes arranged in a row, and the vertical holes extend downward from the upper surface of the CQD layer but do not pass through the CQD layer; The P3HT material in the P3HT layer fully fills the vertical holes in the CQD layer and covers the entire upper surface of the CQD layer.

[0008] Furthermore, the thickness of the ITO electrode layer is 35-45 nm.

[0009] Furthermore, the thickness of the ZnO layer is 390-410 nm.

[0010] Furthermore, the thickness of the CQD layer is 390-410 nm.

[0011] Furthermore, the thickness of the P3HT layer is 390-410 nm.

[0012] Furthermore, the thickness of the MoO3 layer is 35-45 nm.

[0013] Furthermore, the thickness of the Ag electrode layer is 35-45 nm.

[0014] A method for preparing an organic photodetector based on a quantum dot active layer processing strategy, characterized in that the method comprises: S1. Providing a glass substrate; S2. Fabricating an ITO electrode layer on a glass substrate; S3. depositing a ZnO layer on the ITO electrode layer; S4. Spin coating a CQD layer on the ZnO layer; S5. A plurality of cavities are formed by pressing an aluminum-based template having a nanopore structure on the upper surface of the CQD layer; S6. depositing a P3HT layer on the CQD layer; S7. depositing a MoO3 layer on the P3HT layer; S8. Fabricate a Ag electrode layer on the MoO3 layer.

[0015] The present invention introduces an aluminum-based template with a nanopore structure and presses it on the quantum dot layer with a certain pressure to form a plurality of cavities on the top of the quantum dot layer, so as to change the surface morphology of the quantum dot layer and increase the contact area between the quantum dot layer and the organic layer; the P3HT layer is deposited in the cavities on the top of the quantum dot layer, the contact area with the quantum dot layer is increased, the migration rate of photogenerated carriers is increased, and the response performance of the photodetector is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the side section structure of the detector of the present invention.

[0017] Figure 2 It is a comparison diagram of the responsivity of the detector of the present invention with an absorption peak at 1550nm and the responsivity of a conventional detector.

[0018] Figure 3 This is a comparison chart between the responsivity of the detector of the present invention with an absorption peak at 1310 nm and the responsivity of a conventional detector. DETAILED DESCRIPTION

[0019] like Figure 1 Shown: An organic photodetector based on a quantum dot active layer processing strategy, the structure of which includes: a glass substrate layer, an ITO electrode layer, a ZnO layer, a CQD layer, a P3HT layer, a MoO3 layer, and an Ag electrode layer.

[0020] The ITO electrode layer is on the glass substrate layer; the ZnO layer is on the ITO electrode layer; the CQD layer is on the ZnO layer; the P3HT layer is on the CQD layer; the MoO3 layer is on the P3HT layer; and the Ag electrode layer is on the MoO3 layer.

[0021] The ITO electrode layer is made on a glass substrate, and the thickness of the ITO electrode layer is 35-45nm; The ZnO layer is deposited on the ITO electrode layer, and the thickness of the ZnO layer is 390-410nm; The CQD layer is spin-coated on the ZnO layer, and the thickness of the CQD layer is 390-410nm; The P3HT layer is deposited on the CQD layer, and the thickness of the P3HT layer is 390-410nm; The MoO3 layer is deposited on the P3HT layer, and the thickness of the MoO3 layer is 35-45nm; The Ag electrode layer is made on the MoO3 layer, and the thickness of the Ag electrode layer is 35-45nm.

[0022] A method for preparing an organic photodetector based on a quantum dot active layer processing strategy of the present invention: S1. Providing a glass substrate; S2. Fabricating an ITO electrode layer on a glass substrate; S3. depositing a ZnO layer on the ITO electrode layer; S4. Spin coating a CQD layer on the ZnO layer; S5. A plurality of cavities are formed by pressing an aluminum-based template having a nanopore structure on the upper surface of the CQD layer; S6. depositing a P3HT layer on the CQD layer; S7. depositing a MoO3 layer on the P3HT layer; S8. Fabricate a Ag electrode layer on the MoO3 layer.

[0023] Embodiment 1 The present invention provides a method for preparing an organic photodetector based on a quantum dot active layer processing strategy: S1, ITO electrode layer is made on a glass substrate, and the thickness of the ITO electrode layer is 35 nm; S2, ZnO layer is deposited on the ITO electrode layer, and the thickness of the ZnO layer is 390 nm; S3, PbSe quantum dot layer is spin-coated on the ZnO layer, and the thickness of the PbSe quantum dot layer is 390nm; S4, forming a plurality of cavities on the upper surface of the PbSe quantum dot layer by pressing an aluminum-based template having a nanopore structure; S5, P3HT layer is deposited on the CQD layer, and the thickness of the P3HT layer is 390 nm; S6, MoO3 layer is deposited on the P3HT layer, and the thickness of the MoO3 layer is 35 nm; S7, a Ag electrode layer is fabricated on the MoO3 layer, and the thickness of the Ag electrode layer is 35 nm.

[0024] A bias voltage is applied to both ends of the device to put the heterojunction in a reverse bias state. The target light passes through the heterojunction and generates photogenerated carriers. Under the action of the built-in electric field, the photogenerated carriers are output from the device by the hole transport layer and the electron transport layer respectively, forming a photocurrent. The incident target light is detected by measuring the photocurrent. In this embodiment, the absorption peak of the PbSe quantum dots is located at 1550nm. The responsivity of the photodetector is as follows: Figure 2 As shown, the responsivity of the organic photodetector of the present invention is higher than that of the conventional detector. In summary, the responsivity of the photodetector in the first embodiment is better than that of the conventional detector.

[0025] Embodiment 2 The present invention provides a method for preparing an organic photodetector based on a quantum dot active layer processing strategy: S1, ITO electrode layer is made on a glass substrate, and the thickness of the ITO electrode layer is 40 nm; S2, ZnO layer is deposited on the ITO electrode layer, and the thickness of the ZnO layer is 400 nm; S3, PbSe quantum dot layer is spin-coated on the ZnO layer, and the thickness of the PbSe quantum dot layer is 400nm; S4, forming a plurality of cavities on the upper surface of the PbSe quantum dot layer by pressing an aluminum-based template having a nanopore structure; S5, P3HT layer is deposited on the CQD layer, and the thickness of the P3HT layer is 400 nm; S6, MoO3 layer is deposited on the P3HT layer, and the thickness of the MoO3 layer is 40 nm; S7, a Ag electrode layer is fabricated on the MoO3 layer, and the thickness of the Ag electrode layer is 40 nm.

[0026] A bias voltage is applied to both ends of the device to put the heterojunction in a reverse bias state. The target light passes through the heterojunction and generates photogenerated carriers. Under the action of the built-in electric field, the photogenerated carriers are output from the device by the hole transport layer and the electron transport layer respectively, forming a photocurrent. The incident target light is detected by measuring the photocurrent. In this embodiment, the absorption peak of the PbSe quantum dots is located at 1310nm. The responsivity of the photodetector is as follows: Figure 3 As shown, the responsivity of the organic photodetector of the present invention is higher than that of the conventional detector. In summary, the responsivity of the photodetector in the second embodiment is better than that of the conventional detector.

[0027] In the embodiment, the materials of the quantum dot photosensitive layer and the organic photosensitive layer can be selected and replaced according to actual needs. By pressing on the top of the quantum dot layer to form a cavity, the organic layer enters the cavity, thereby increasing the contact area between the quantum dot layer and the organic layer. When a reverse bias voltage is applied to the device, the heterojunction will be in a reverse bias state, and the photogenerated electrons and holes will be transmitted to the outside of the device through the electron transport layer and the hole transport layer respectively to form a photocurrent.

Claims

1. An organic photodetector based on a quantum dot active layer processing strategy, characterized in that: The structure of the organic photodetector includes, from bottom to top, a glass substrate layer, an ITO electrode layer, a ZnO layer, a CQD layer, a P3HT layer, a MoO3 layer, and an Ag electrode layer; the ITO electrode layer represents an indium tin oxide electrode layer, the CQD layer represents a colloidal quantum dot layer, and the P3HT layer is a polymer layer of 3-hexylthiophene; the CQD layer is provided with vertical holes arranged in a row, and the vertical holes extend downward from the upper surface of the CQD layer but do not pass through the CQD layer; The P3HT material in the P3HT layer fully fills the vertical holes in the CQD layer and covers the entire upper surface of the CQD layer.

2. An organic photodetector based on a quantum dot active layer processing strategy as claimed in claim 1, characterized in that: The thickness of the ITO electrode layer is 35-45 nm.

3. An organic photodetector based on a quantum dot active layer processing strategy as claimed in claim 1, characterized in that: The thickness of the ZnO layer is 390-410 nm.

4. An organic photodetector based on a quantum dot active layer processing strategy as claimed in claim 1, characterized in that: The thickness of the CQD layer is 390-410 nm.

5. An organic photodetector based on a quantum dot active layer processing strategy as claimed in claim 1, characterized in that: The thickness of the P3HT layer is 390-410 nm.

6. An organic photodetector based on a quantum dot active layer processing strategy as claimed in claim 1, characterized in that: The thickness of the MoO3 layer is 35-45 nm.

7. An organic photodetector based on a quantum dot active layer processing strategy as claimed in claim 1, characterized in that: The thickness of the Ag electrode layer is 35-45 nm.

8. The method for preparing an organic photodetector based on a quantum dot active layer processing strategy according to claim 1, characterized in that: The method includes: S1. Providing a glass substrate; S2. Fabricating an ITO electrode layer on a glass substrate; S3. depositing a ZnO layer on the ITO electrode layer; S4. Spin coating a CQD layer on the ZnO layer; S5. A plurality of cavities are formed by pressing an aluminum-based template having a nanopore structure on the upper surface of the CQD layer; S6. depositing a P3HT layer on the CQD layer; S7. depositing a MoO3 layer on the P3HT layer; S8. Fabricate a Ag electrode layer on the MoO3 layer.

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