A high-detectivity all-polymer multiplication organic photodetector structure and a preparation method thereof

Abstract

The application relates to a high-detectivity all-polymer multiplication organic photodetector structure and a preparation method thereof. The structure comprises a substrate, an anode, a hole transport layer, an active layer, an electron transport layer and a cathode which are sequentially grown from bottom to top; and PS is added in the active layer. The application selects an insulating polymer PS as an additive, maintains low dark current of the photodetector, improves external quantum efficiency of the device, and thus realizes improvement of detectivity in a wide spectral range.

Description

TECHNICAL FIELD

[0001] The present application relates to a high-detectivity all-polymer multiplication organic photodetector structure and a preparation method thereof, and belongs to the technical field of organic photodetector structure preparation. BACKGROUND

[0002] As a promising photodetection technology, organic photomultiplier detectors have made great progress in recent years due to various optimization methods and designs of new materials. However, at high operating voltages, specific detection performance problems caused by mutual repulsion of significant gain and low dark current limit its further development and commercial application. Therefore, high specificity detection is crucial for its commercial development. Low-cost insulating polymers show rich functions, accelerating their application in organic semiconductors. It can fill the defects of the active layer, optimize the film morphology, and promote carrier transport. Therefore, this molecule can effectively improve the hole tunneling from the metal cathode by enhancing the interface electron trap effect, thereby improving the photoelectric multiplication effect of organic all-high molecular materials. It produces higher external quantum efficiency and lower dark current density. Ultimately, by applying only-10V in the PBDB-T:N2200 system, the PS-doped device appears at 450nm with an LDR of more than 100dB, thereby obtaining a 4.0х10 13 Jones' excellent specific detection rate.

[0003] In recent years, due to the advantages of organic materials such as flexibility, tunable absorption, light weight, etc., organic photodetectors have made great progress in a wide range of fields such as military, communication, health monitoring, near-infrared sensing, etc. As a performance indicator of organic photodetectors, specific detection rate reflects the ability of the detector to detect weak light signals. In order to detect lower intensity signals, devices with high specific detection rate (D*) are needed. It is through the interface trap-induced charge tunnel injection that the photo-multiplication organic photodetector (PM-OPD) can achieve higher external quantum efficiency (EQE), which provides a new idea for improving the detection rate. However, improving EQE by applying an external bias can cause an increase in the dark current of the device. Therefore, due to the mutual restriction of EQE and dark current, the specific detection problem is still the main obstacle limiting the application of organic photodetectors. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application provides a high-detectivity all-polymer multiplication organic photodetector structure; the present application also provides a method for preparing a high-detectivity all-polymer multiplication organic photodetector structure by doping an insulating substance;

[0005] In the present application, the insulating polymer as a promising dopant for photo-multiplication type organic photodetectors paves the way for commercial related photodetector technology.

[0006] The present application solves the above problems by using a new method of controlling the PM-OPD active layer treatment by adding an appropriate amount of inert high molecular weight polystyrene (PS). First, a heterojunction active layer of all-polymer organic material is prepared by spin coating method, and PM-OPDs are successfully prepared; in this process, a solution with a large concentration is used to prepare a thick active layer film to keep the dark current value of the device at a low level. At the same time, PS is added to the active layer to improve the external quantum efficiency of the device, so that a high-performance probe rate device is obtained.

[0007] Term explanation:

[0008] 1. PBDB-T is a kind of polymer photovoltaic material with high efficiency at present, mainly used as donor material of organic photodetector.

[0009] 2. N2200: a kind of polymer acceptor material, mainly used as acceptor material of organic photodetector.

[0010] 3. PM6: a kind of polymer photovoltaic material, used as donor material of photodetector.

[0011] 4. PY-IT: a kind of polymer acceptor, D-A type copolymer acceptor. Mainly used as acceptor material of organic photodetector.

[0012] 5. PCE10: one of the new generation of donor polymers, used as donor material of photodetector.

[0013] The technical scheme of the present application is:

[0014] A kind of all-polymer multiplication organic photodetector structure with high probe rate, including substrate, anode, hole transport layer, active layer, electron transport layer and cathode grown from bottom to top in turn; PS is added to the donor-acceptor of the active layer.

[0015] According to the present application, the mass ratio of PS to donor in the active layer is 0-20%;

[0016] According to the present application, the donor-acceptor is PBDB-T:N2200, PM6:PY-IT or PCE10:N2200;

[0017] According to the present application, the mass ratio of PBDB-T:N2200 is 100:2, the mass ratio of PM6:PY-IT is 100:2, and the mass ratio of PCE10:N2200 is 100:2.

[0018] According to the present application, when the donor-acceptor is PBDB-T:N2200, the mass ratio of PS to donor is 4%;

[0019] When the acceptor is PM6:PY-IT, the mass ratio of PS to the donor is 12%;

[0020] When the acceptor is PCE10:N2200, the mass ratio of PS to the donor is 8%.

[0021] According to the application, preferably, the substrate is a glass substrate, the anode is a transparent conductive film, the material of the hole transport layer is PEDOT:PSS, the material of the electron transport layer is PDIN or PDINN, and the cathode is Ag or Al.

[0022] The preparation method of the all-polymer multiplication organic photodetector structure comprises the following steps:

[0023] The hole transport layer is prepared by spin coating on the surface of the conductive glass.

[0024] The active layer is prepared by spin coating the active layer material on the hole transport layer in a nitrogen atmosphere.

[0025] The electron transport layer is prepared by spin coating on the surface of the active layer.

[0026] The cathode is prepared on the electron transport layer under vacuum conditions, and the all-polymer multiplication organic photodetector structure is obtained.

[0027] The active layer material contains different contents of PS.

[0028] According to the application, preferably, the active layer is prepared by spin coating the active layer material on the hole transport layer in a nitrogen atmosphere, and the preparation method comprises the following steps:

[0029] The active layer material is spin coated on the hole transport layer in a nitrogen atmosphere, the rotation speed is 800-1200 rpm under chlorobenzene solvent for 50-80 s, and the active layer is annealed at 110°C for 5-15 min.

[0030] Further preferably, the active layer material is spin coated on the hole transport layer in a nitrogen atmosphere, the rotation speed is 1000 rpm under chlorobenzene solvent for 50 s, and the active layer is annealed at 110°C for 10 min.

[0031] According to the application, preferably, the active layer is prepared by spin coating the active layer material on the hole transport layer in a nitrogen atmosphere, and the preparation method comprises the following steps:

[0032] The active layer material is spin coated on the hole transport layer in a nitrogen atmosphere, the rotation speed is 1500-2500 rpm under chloroform solvent for 30-40 s, and the active layer is annealed at 100°C for 5-15 min.

[0033] Further preferably, the active layer material is spin coated on the hole transport layer in a nitrogen atmosphere, the rotation speed is 2000 rpm under chloroform solvent for 30 s, and the active layer is annealed at 100°C for 5 min.

[0034] According to the present application, preferably, the conductive glass is ITO conductive glass; before preparing the hole transport layer, the following operations are performed:

[0035] The ITO conductive glass is sequentially cleaned with cleaning agent, deionized water, acetone, anhydrous ethanol and isopropyl alcohol by ultrasonic cleaning, and dried with nitrogen, and then treated with UV for 10-18 min.

[0036] Further preferably, the UV treatment is performed for 15 min.

[0037] According to the present application, preferably, the hole transport layer is prepared by spin coating on the surface of the conductive glass, comprising:

[0038] The PEDOT:PSS is spin coated on the surface of the conductive glass, and annealed at 140-180°C for 10-20 min.

[0039] Further preferably, the PEDOT:PSS is spin coated on the surface of the conductive glass, and annealed at 150°C for 15 min.

[0040] According to the present application, preferably, the electron transport layer is prepared by spin coating on the surface of the active layer, comprising:

[0041] The PDIN solution of 1.5-2 mg / mL is spin coated on the active layer at a speed of 3000-6000 rpm for 20-40 s;

[0042] Further preferably, the PDIN solution of 2 mg / mL is spin coated on the active layer at a speed of 5000 rpm for 30 s.

[0043] According to the present application, preferably, the electron transport layer is prepared by spin coating on the surface of the active layer, comprising:

[0044] The PDINN solution of 1.5-2 mg / mL is spin coated on the active layer at a speed of 2000-4000 rpm for 20-40 s;

[0045] Further preferably, the PDINN solution of 1.5 mg / mL is spin coated on the active layer at a speed of 3000 rpm for 30 s.

[0046] According to the present application, preferably, the cathode is prepared on the electron transport layer under vacuum conditions, comprising:

[0047] The Al electrode or Ag electrode of 80-100 nm is prepared by thermal evaporation under vacuum conditions of 9х10 -3 Pa-4х10 -4 Pa.

[0048] Further preferably, the Al electrode or Ag electrode of 100 nm is prepared by thermal evaporation under vacuum conditions of 4х10 -4 Pa.

[0049] The beneficial effects of the present application are:

[0050] 1、The present application selects insulating polymer PS as an additive, maintains the low dark current of the photodetector, improves the external quantum efficiency of the device, and thus realizes the improvement of the detection rate in a wide spectral range. The strategy is applied to 3 groups of material systems, and when a proper proportion of PS is added, the external quantum efficiency (EQE) of all material systems is improved.

[0051] 2、The present application can improve the film morphology, reduce the defect state density, improve the exciton lifetime and thus optimize the performance of the all-polymer PM-OPD by adding the insulating polymer PS. BRIEF DESCRIPTION OF DRAWINGS

[0052] Figure 1 Structure diagram of the high-detection-rate all-polymer multiplication organic photodetector structure of the present application Figure 1 ;

[0053] Figure 2 Structure diagram of the high-detection-rate all-polymer multiplication organic photodetector structure of the present application Figure 2 ;

[0054] Figure 3 EQE spectrum diagram of the high-detection-rate all-polymer multiplication organic photodetector PBDB-T:N2200 system doped with different proportions of PS of the present application

[0055] Figure 4 Detection rate spectrum diagram of the high-detection-rate all-polymer multiplication organic photodetector PBDB-T:N2200 system doped with different proportions of PS of the present application

[0056] Figure 5 EQE spectrum diagram of the high-detection-rate all-polymer multiplication organic photodetector PM6:PY-IT system doped with different proportions of PS of the present application

[0057] Figure 6 Detection rate spectrum diagram of the high-detection-rate all-polymer multiplication organic photodetector PM6:PY-IT system doped with different proportions of PS of the present application

[0058] Figure 7 EQE spectrum diagram of the high-detection-rate all-polymer multiplication organic photodetector PCE10:N2200 system doped with different proportions of PS of the present application

[0059] Figure 8 Detection rate spectrum diagram of the high-detection-rate all-polymer multiplication organic photodetector PCE10:N2200 system doped with different proportions of PS of the present application DETAILED DESCRIPTION

[0060] The application will be further defined with the help of the accompanying drawings and examples, but is not limited thereto.

[0061] Example 1

[0062] A high-detectivity all-polymer multiplication organic photodetector structure, as shown in Figure 1 or Figure 2 includes, from bottom to top, a substrate, an anode, a hole transport layer, an active layer, an electron transport layer and a cathode; the donor-acceptor of the active layer is added with PS.

[0063] The substrate is a glass substrate, the anode is a transparent conductive film, the material of the hole transport layer is PEDOT:PSS; the material of the electron transport layer is PDIN or PDINN; and the cathode is Ag or Al.

[0064] The insulating polymer PS is selected as an additive, which maintains the low dark current of the photodetector while improving the external quantum efficiency of the device, thereby realizing the improvement of the detectivity in a wide spectral range.

[0065] Example 2

[0066] The high-detectivity all-polymer multiplication organic photodetector structure according to example 1, which is different in that:

[0067] In the active layer, the mass ratio of PS to the donor is 0-20%.

[0068] The donor-acceptor is PBDB-T:N2200, PM6:PY-IT or PCE10:N2200.

[0069] Example 3

[0070] The high-detectivity all-polymer multiplication organic photodetector structure according to example 2, which is different in that:

[0071] When the donor-acceptor is PBDB-T:N2200, the mass ratio of PS to the donor is 4%.

[0072] Figure 3 EQE spectrum of the high-detectivity all-polymer multiplication organic photodetector PBDB-T:N2200 system doped with different proportions of PS according to the application; the abscissa is wavelength, and the ordinate is the external quantum efficiency of the device; when the amount of PS added is 4%, the EQE of the device is most obviously improved, which is reduced by about 50%, and at the same time, the addition of PS does not sacrifice the dark current, on the contrary, the device containing PS in the PBDB-T:N2200 system is also reduced, so the detectivity of the system is also obviously improved.

[0073] Figure 4The detection rate spectrum of the high-detection-rate all-polymer multiplication organic photodetector PBDB-T:N2200 system doped with different proportions of PS according to the application; the abscissa is wavelength, and the ordinate is the detection rate of the device.

[0074] Through experimental verification, the EQE and D* of the device with a proper proportion of insulating polymer are significantly improved, taking the all-polymer PBDB-T:N2200 system as an example. At the same time, the dark current of the PS doped device is appropriately reduced due to the reduction of trap density and the increase of film thickness. Therefore, it is observed that the successful all-polymer PM-OPD has a D* of 4.0х10 13 Jones's high specificity detection rate.

[0075] Example 4

[0076] The high-detection-rate all-polymer multiplication organic photodetector structure according to example 2, which is different in that:

[0077] When the donor-acceptor is PM6:PY-IT, the mass ratio of PS to the donor is 12%.

[0078] Only considering the shot noise of the device, the expression of the detection rate can be written as follows:

[0079]

[0080] Where q is the charge unit, λ is the wavelength, A is the device area, h and c are the Planck constant and the speed of light, J d is the dark current density.

[0081] Figure 5 The EQE spectrum of the high-detection-rate all-polymer multiplication organic photodetector PM6:PY-IT system doped with different proportions of PS according to the application; the abscissa is wavelength, and the ordinate is the external quantum efficiency of the device. Figure 6 The detection rate spectrum of the high-detection-rate all-polymer multiplication organic photodetector PM6:PY-IT system doped with different proportions of PS according to the application; the abscissa is wavelength, and the ordinate is the detection rate of the device.

[0082] Example 5

[0083] The high-detection-rate all-polymer multiplication organic photodetector structure according to example 2, which is different in that:

[0084] When the donor-acceptor is PCE10:N2200, the mass ratio of PS to the donor is 8%.

[0085] Figure 7 The EQE spectrum of the high-detection-rate all-polymer multiplication organic photodetector PCE10:N2200 system doped with different proportions of PS according to the application; the abscissa is wavelength, and the ordinate is the external quantum efficiency of the device.Figure 8 The detection rate spectrum of the all-polymer multiplication organic photoelectric detector PCE10:N2200 system doped with different proportions of PS according to the present application; the abscissa is wavelength, and the ordinate is the detection rate of the device.

[0086] Embodiment 6

[0087] The preparation method of the all-polymer multiplication organic photoelectric detector structure according to any one of Embodiments 1-5, comprising:

[0088] spinning to prepare a hole transport layer on the surface of the conductive glass;

[0089] spinning to prepare an active layer on the hole transport layer under a nitrogen atmosphere;

[0090] spinning to prepare an electron transport layer on the surface of the active layer;

[0091] preparing a cathode on the electron transport layer under vacuum conditions, thus obtaining the all-polymer multiplication organic photoelectric detector structure;

[0092] wherein different contents of PS are added to the active layer material.

[0093] Embodiment 7

[0094] The preparation method of the all-polymer multiplication organic photoelectric detector structure according to Embodiment 6, comprising:

[0095] spinning to prepare an active layer on the hole transport layer under a nitrogen atmosphere, comprising: spinning to prepare an active layer on the hole transport layer under a nitrogen atmosphere, the rotation speed being 800-1200 rpm under a chlorobenzene solvent for 50-80 s, and annealing at 110°C for 5-15 min.

[0096] The conductive glass is ITO conductive glass; before the hole transport layer is prepared, the following operations are performed:

[0097] The ITO conductive glass is sequentially cleaned with a cleaning agent, deionized water, acetone, anhydrous ethanol, and isopropyl alcohol under ultrasonic cleaning, and is dried with nitrogen, and is then treated with UV for 10-18 min.

[0098] spinning to prepare a hole transport layer on the surface of the conductive glass, comprising: spinning PEDOT:PSS on the surface of the conductive glass, and annealing at 140-180°C for 10-20 min.

[0099] spinning to prepare an electron transport layer on the surface of the active layer, comprising: spinning a PDIN solution with a concentration of 1.5-2 mg / mL on the active layer at a rotation speed of 3000-6000 rpm for 20-40 s.

[0100] According to the present application, preferably, the cathode is prepared on the electron transport layer under vacuum conditions, comprising:

[0101] In 9x10 -3 Pa-4x10 -4 An Al electrode or Ag electrode of 80-100 nm is prepared by thermal evaporation under vacuum condition of Pa.

[0102] Example 8

[0103] The preparation method of the all-polymer multiplication organic photodetector structure according to example 7, comprising:

[0104] The active layer material is spin-coated on the hole transport layer under nitrogen atmosphere, at a speed of 1000 rpm for 50 s in chlorobenzene solvent, and annealed at 110°C for 10 min.

[0105] UV treatment for 15 min;

[0106] PEDOT:PSS is spin-coated on the surface of the conductive glass, and annealed at 150°C for 15 min.

[0107] The PDIN solution of 2 mg / mL is spin-coated on the active layer at a speed of 5000 rpm for 30 s.

[0108] In 4x10 -4 An Al electrode or Ag electrode of 100 nm is prepared by thermal evaporation under vacuum condition of Pa.

[0109] Example 9

[0110] The preparation method of the all-polymer multiplication organic photodetector structure according to example 7, comprising:

[0111] The active layer material is spin-coated on the hole transport layer under nitrogen atmosphere, and the active layer is prepared, comprising: spin-coating the active layer material on the hole transport layer under nitrogen atmosphere, at a speed of 1500-2500 rpm for 30-40 s in chloroform solvent, and annealing at 100°C for 5-15 min;

[0112] The electron transport layer is prepared by spin-coating on the surface of the active layer, comprising: spin-coating the PDINN solution of 1.5-2 mg / mL on the active layer at a speed of 2000-4000 rpm for 20-40 s.

[0113] Example 10

[0114] The preparation method of the all-polymer multiplication organic photodetector structure according to example 9, comprising:

[0115] The active layer material is spin-coated on the hole transport layer under nitrogen atmosphere, at a speed of 2000 rpm for 30 s in chloroform solvent, and annealed at 100°C for 5 min.

[0116] A 1.5 mg / mL solution of PDINN was spin-coated onto the active layer at 3000 rpm for 30 s.

Claims

1. A high-detectivity all-polymer multiplying organic photodetector structure, characterized in that, It includes a substrate, an anode, a hole transport layer, an active layer, an electron transport layer, and a cathode, grown sequentially from bottom to top; PS is added to the donor and acceptor layers of the active layer; The mass ratio of PS to donor is 0-20%.

2. The high detectivity all-polymer multiplying organic photodetector structure according to claim 1, characterized in that, The receptors are PBDB-T:N2200, PM6:PY-IT, or PCE10:N2200.

3. The high detectivity all-polymer multiplying organic photodetector structure according to claim 2, characterized in that, The ratio of PBDB-T to N2200 is 100:2, PM6 to PY-IT is 100:2, and PCE10 to N2200 is 100:

2.

4. The high detectivity all-polymer multiplying organic photodetector structure according to claim 1, characterized in that, When the acceptor is PBDB-T:N2200, the mass ratio of PS to donor is 4%. When the acceptor is PM6:PY-IT, the mass ratio of PS to donor is 12%. When the acceptor is PCE10:N2200, the mass ratio of PS to donor is 8%.

5. A high-detectivity all-polymer multiplying organic photodetector structure according to any one of claims 1-4, characterized in that, The substrate is a glass substrate, the anode is a transparent conductive film, the hole transport layer is made of PEDOT:PSS, the electron transport layer is made of PDIN or PDINN, and the cathode is made of Ag or Al.

6. The method for preparing the all-polymer multiplying organic photodetector structure according to any one of claims 1-4, characterized in that, include: A hole transport layer was prepared by spin-coating on a conductive glass surface; An active layer is prepared by spin-coating an active layer material onto a hole transport layer under a nitrogen atmosphere. An electron transport layer was prepared by spin-coating the surface of the active layer. A cathode is fabricated on an electron transport layer under vacuum conditions, thus obtaining the desired result. Different amounts of PS are added to the active layer material.

7. The method for fabricating the all-polymer multiplying organic photodetector structure according to claim 6, characterized in that, Under a nitrogen atmosphere, an active layer material is spin-coated onto the hole transport layer to prepare the active layer, including: Under a nitrogen atmosphere, the active layer material is spin-coated onto the hole transport layer at a speed of 800-1200 rpm for 50-80 seconds in chlorobenzene solvent, followed by annealing at 110℃ for 5-15 minutes.

8. The method for fabricating the all-polymer multiplying organic photodetector structure according to claim 7, characterized in that, Under a nitrogen atmosphere, the active layer material was spin-coated onto the hole transport layer at a speed of 1000 rpm for 50 s in chlorobenzene solvent, followed by annealing at 110℃ for 10 min.

9. The method for fabricating the all-polymer multiplying organic photodetector structure according to claim 6, characterized in that, Under a nitrogen atmosphere, an active layer material is spin-coated onto the hole transport layer to prepare the active layer, including: Under a nitrogen atmosphere, the active layer material is spin-coated onto the hole transport layer at a speed of 1500-2500 rpm for 30-40 seconds in chloroform solvent, followed by annealing at 100℃ for 5-15 minutes.

10. The method for fabricating the all-polymer multiplying organic photodetector structure according to claim 9, characterized in that, Under a nitrogen atmosphere, the active layer material was spin-coated onto the hole transport layer at a speed of 2000 rpm for 30 s in chloroform solvent, followed by annealing at 100°C for 5 min.

11. The method for fabricating the all-polymer multiplying organic photodetector structure according to claim 6, characterized in that, A hole transport layer is prepared by spin-coating on a conductive glass surface, including: Spin-coat PEDOT:PSS onto the conductive glass surface and anneal at 140-180℃ for 10-20 min.

12. The method for fabricating the all-polymer multiplying organic photodetector structure according to claim 11, characterized in that, Spin-coat PEDOT:PSS onto the conductive glass surface and anneal at 150°C for 15 min.

13. The method for fabricating the all-polymer multiplying organic photodetector structure according to any one of claims 7-12, characterized in that, An electron transport layer is prepared by spin-coating on the surface of the active layer, including: Spin-coat a 1.5-2 mg / mL PDIN solution onto the active layer at a speed of 3000-6000 rpm for 20-40 seconds.

14. The method for fabricating the all-polymer multiplying organic photodetector structure according to claim 13, characterized in that, Spin-coat a 2 mg / mL PDIN solution onto the active layer at 5000 rpm for 30 seconds.

15. The method for fabricating the all-polymer multiplying organic photodetector structure according to any one of claims 7-12, characterized in that, The electron transport layer is prepared by spin-coating on the surface of the active layer, including: spin-coating a 1.5-2 mg / mL PDINN solution onto the active layer at a speed of 2000-4000 rpm for 20-40 s. Fabrication of a cathode on an electron transport layer under vacuum conditions includes: In 9x10 -3 Pa-4х10 -4 Al or Ag electrodes with a diameter of 80-100 nm were prepared by thermal evaporation under vacuum conditions of Pa. The conductive glass is ITO conductive glass; before fabricating the hole transport layer, the following operations are performed: The ITO conductive glass was ultrasonically cleaned sequentially with cleaning agent, deionized water, acetone, anhydrous ethanol and isopropanol, dried with nitrogen, and then treated with UV for 10-18 minutes.

16. The method for fabricating the all-polymer multiplying organic photodetector structure according to claim 15, characterized in that, Spin-coat a 1.5 mg / mL PDINN solution onto the active layer at 3000 rpm for 30 seconds. In 4x10 -4 100 nm Al or Ag electrodes were prepared by thermal evaporation under vacuum conditions of Pa. Treat with UV for 15 min.

Images