High-performance multispectral organic photoelectric detector based on cage molecule passivation

Abstract

The invention discloses a high-performance multispectral organic photoelectric detector based on cage molecule passivation, and belongs to the field of photoelectric detectors. The organic photoelectric detector comprises a metal electrode, an electron transport layer, a rear-end BHJ layer, a first cage-shaped molecule non-contact passivation layer, a carrier selective permeation layer, a second cage-shaped molecule non-contact passivation layer, a front-end BHJ layer, an electron transport layer and a transparent conductive substrate which are sequentially arranged from bottom to top, wherein the first cage-shaped molecule non-contact passivation layer and the second cage-shaped molecule non-contact passivation layer are made of Kuburg cage-shaped molecule series materials. The cage-shaped molecule non-contact passivation layers are formed on the front-end BHJ layer and the rear-end BHJ layer through spin coating, and the non-contact passivation layers effectively cover defect sites, such as unpaired free radicals, fracture bonds or impurity clusters, on the surfaces of the BHJ layers through physical adsorption or Van der Waals force, so that dark current is reduced, the high-noise spectral density is reduced, and the detection rate is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of photoelectric detectors, and particularly relates to a high-performance and multi-spectrum organic photoelectric detector based on cage molecule passivation. BACKGROUND

[0002] Organic photodetectors (OPDs) have attracted much attention in the field of optoelectronics due to their strong material designability, simple preparation process, low cost, and good flexibility compatibility. Compared with traditional inorganic photodetectors (such as silicon-based and InGaAs), OPDs have significant advantages in terms of tunable spectral response range, flexible integration capability, and low-power operation. However, the inherent molecular stacking disorder and interface energy level mismatch of organic semiconductor materials can introduce a large number of deep-level defects, which can exacerbate the non-radiative recombination loss of photo-generated carriers, resulting in high dark current, significant noise, and insufficient environmental stability, which seriously restricts their application in the field of high-performance photodetection.

[0003] To suppress defect state density and improve the detection rate (D*), current strategies mainly include molecular structure optimization, bulk doping, and blending phase engineering. Molecular structure optimization reduces film disorder through molecular conformation locking effect, thereby suppressing non-radiative recombination and improving the detection rate. However, this strategy faces problems such as low yield of organic molecule synthesis, harsh process conditions, and high cost. Bulk doping and blending strategies avoid complex synthesis steps, but they have defects such as uneven distribution of dopants and phase separation over time, which can lead to decreased device yield and shortened device lifetime. SUMMARY

[0004] The present application aims to provide a high-performance and multi-spectrum organic photoelectric detector based on cage molecule passivation to address the problems in the background art. The present application utilizes cage molecules to effectively passivate internal and interface defects in the organic photoactive layer based on a back-to-back stacked bulk heterojunction (BHJ) structure, thereby improving the overall performance of the photoelectric detector.

[0005] To achieve the above-mentioned purposes, the technical solutions adopted by the present application are as follows:

[0006] A high-performance and multi-spectrum organic photoelectric detector based on cage molecule passivation, comprising, from bottom to top, a metal electrode, an electron transport layer, a rear-end BHJ layer, a first cage molecule non-contact passivation layer, a carrier selection transmission layer, a second cage molecule non-contact passivation layer, a front-end BHJ layer, an electron transport layer, and a transparent conductive substrate; wherein the materials of the first and second cage molecule non-contact passivation layers are CC series materials.

[0007] Preferably, the material of the first and second cage-like molecule non-contact passivation layer is an amine group molecular cage, specifically RCC1, RCC2 or RCC3.

[0008] Further, the thickness of the first and second cage-like molecule non-contact passivation layer is 1-8 nm.

[0009] Further, the front-end BHJ layer is PTB7-Th:PC 71 BM, PM6:BTP-eC9, PM6:L8-Ph, PM6:Y6-BO, m-DTC-Cl-2 and other organic photovoltaic materials; the back-end BHJ layer is PTB7-Th:CO i 8DFIC:PC 71 BM, PBQx-H-TF / PBTIC-γ-TSe, BTPV-4Cl, PBQ6:PYF-T-o and other organic photovoltaic materials.

[0010] Preferably, the front-end BHJ layer is PTB7-Th:PC 71 BM, with a thickness of 625 nm, prepared by solution processing method of PTB7-Th and PC 71 BM in a mass ratio of 1:1:0.5.

[0011] Preferably, the back-end BHJ layer is PTB7-Th:CO i 8DFIC:PC 71 BM, with a thickness of 95 nm, prepared by solution processing method of PTB7-Th, CO i 8DFIC, PC 71 BM in a mass ratio of 1:1:0.5.

[0012] Further, the material of the carrier selection transmission layer is a p-type semiconductor material with excellent conductivity, specifically MoO3, NiO, CuI, CuSCN and the like.

[0013] Further, the thickness of the carrier selection transmission layer is 5 nm.

[0014] Further, the material of the electron transport layer is an n-type semiconductor material with good conductivity, specifically SnO2, TiO2, ZnO, C 60 in combination.

[0015] Further, the transparent conductive substrate is a transparent conductive glass, specifically ITO or FTO.

[0016] Further, the material of the metal electrode is Au, Ag, Pt or carbon, with a thickness of 100 nm.

[0017] Further, the first cage molecule non-contact passivation layer and the second cage molecule non-contact passivation layer are prepared by a spin coating method.

[0018] Compared with the prior art, the present application has the following beneficial effects:

[0019] 1. The high-performance, multi-spectral organic photodetector based on cage molecule passivation disclosed by the present application forms a cage molecule non-contact passivation layer on the front-end BHJ layer and the rear-end BHJ layer by spin coating, and the non-contact passivation layer effectively covers the defect sites on the surface of the BHJ layer, such as unpaired free radicals, broken bonds or impurity clusters, by physical adsorption or van der Waals force, so that the dark current is reduced, the high noise spectral density is reduced, and the detection rate (D * ) is improved.

[0020] 2. The high-performance, multi-spectral organic photodetector based on cage molecule passivation disclosed by the present application uses RCC series (amine molecular cage) materials to form a dense cage molecule layer on the surface of the BHJ layer, and due to the van der Waals force interaction between the hydrogen atoms on the surface of the cage molecule and the atoms (such as sulfur atoms in the thiophene structure) on the contact surface of the hole semi-crystalline conductive polymer in the organic active light absorption layer (BHJ layer), the hole semi-crystalline conductive polymer is induced to stack and arrange after annealing, thereby affecting the energy level distribution of the conduction band and the valence band of the hole semi-crystalline conductive polymer, reducing the tail state area of the hole semi-crystalline conductive polymer, and reducing the defect density, so that the defects in the organic active light absorption layer are controlled, the recombination center is reduced, the significant influence of the trap state is reduced, thereby reducing the dark current and improving the detection rate (D * ). BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 FIG. 1 is a structural schematic diagram of a high-performance, multi-spectral organic photodetector based on cage molecule passivation according to the present application;

[0022] Figure 2 FIG. 5 is a molecular structural formula of PTB7-Th involved in Example 1;

[0023] Figure 3 FIG. 6 is a molecular structural formula of PC 71 BM involved in Example 1;

[0024] Figure 4 FIG. 7 is a molecular structural formula of CO i 8DFIC involved in Example 1;

[0025] Figure 5 FIG. 8 is a molecular structural formula of RCC1 involved in Example 1;

[0026] Figure 6The molecular structural formula of RCC2 involved in Example 2;

[0027] Figure 7 The molecular structural formula of RCC3 involved in Example 1;

[0028] Figure 8 The structural schematic diagram of the detector of Comparative Example 2. DETAILED DESCRIPTION

[0029] In order to make the objects, technical solutions and advantages of the present application clearer, the present application is further described in detail below with reference to the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0030] Example 1

[0031] The present example provides a multi-spectral organic photodetector based on RCC material, the structure is as shown in Figure 1 , which comprises, from bottom to top, a metal electrode (cathode), an electron transport layer, a rear-end BHJ layer, a cage molecule non-contact passivation layer, a carrier selection transmission layer, a cage molecule non-contact passivation layer, a front-end BHJ layer, an electron transport layer and a transparent conductive substrate (anode) arranged in sequence.

[0032] The front-end BHJ layer is PTB7-Th:PC 71 BM, which is prepared by solution processing method through PTB7-Th and PC 71 BM with a mass ratio of 1:1; the rear-end BHJ layer is PTB7-Th:CO i 8DFIC:PC 71 BM, which is prepared by solution processing method through PTB7-Th, CO i 8DFIC, PC 71 BM with a mass ratio of 1:1:0.5; the rear-end BHJ layer is PTB7-Th:CO i 8DFIC, PC 71 BM. The material molecular structural formula of the cage molecule non-contact passivation layer is as shown in Figure 2 , Figure 3 and Figure 4 . The cage molecule non-contact passivation layer is an RCC series material, specifically RCC1, RCC2 or RCC3, and the corresponding material molecular structural formula is as shown in Figure 5 , Figure 6 and Figure 7 . The present example specifically adopts RCC3. The material of the electrode layer is Ag. The material of the electron transport layer is a good conductive n-type semiconductor material, specifically ZnO. The transparent conductive substrate is a transparent conductive glass, specifically an ITO substrate.

[0033] The preparation method of the multispectral organic photodetector based on RCC material proposed in the embodiment comprises the following steps:

[0034] Step 1. Clean the ITO substrate, wipe with detergent and dust-free cloth, clean in distilled water, acetone and isopropanol in sequence for 30 min, then blow dry, and then expose the cleaned ITO / glass substrate to ultraviolet (UV)-ozone treatment for 15 min.

[0035] Step 2. Prepare a ZnO solution: mix 15wt% ZnO nanoparticle aqueous dispersion with deionized water and IPA at a volume ratio of 1:2:2.

[0036] Step 3. Prepare a PTB7-Th:PC71BM solution: dissolve 20mg PTB7-Th and 20mg PC 71 BM in 1mL 1,2-dichlorobenzene.

[0037] Step 4. Prepare a RCC3 solution: dissolve 1mg RCC3 solid in 1mL IPA (isopropanol) and shake uniformly.

[0038] Step 5. First prepare a MoO3 film on the original substrate, and then coat a polymer support layer PMMA.

[0039] Step 6. Prepare a PTB7-Th:CO i 8DFIC:PC 71 BM solution: dissolve 20mg PTB7-Th, 20mg PC 71 BM and 10mg CO i 8DFIC in 1mL 1,2-dichlorobenzene.

[0040] Step 7. Spin and anneal the solutions prepared in steps 2-6 on the ITO substrate treated in step 1 in sequence, specifically: the spin-coating conditions of the ZnO solution are 2500rpm for 50s, followed by annealing at 500℃ with tin paper wrapping for 60min; the spin-coating conditions of the PTB7-Th:PC71BM solution are 1500rpm for 120s, followed by annealing at 120℃ for 5min; the spin-coating conditions of the RCC3 solution are 4000rpm for 30s, followed by annealing at 120℃ for 5min; separate the MoO3 film by etching or mechanical peeling, and dissolve the support layer with acetone, then anneal at low temperature 150℃; the spin-coating conditions of the PTB7-Th:CO i 8DFIC:PC 71The spin coating condition of the BM solution is spin coating at a rotation speed of 1000 rpm for 120 s, followed by annealing at 120℃ for 5 min. The electron transport layer, the front-end BHJ layer, the cage molecule non-contact passivation layer, the carrier selective transmission layer, the cage molecule non-contact passivation layer, the rear-end BHJ layer, and the electron transport layer are sequentially obtained on the ITO substrate.

[0041] Step 8. A 80 nm thick silver electrode layer is evaporated on the surface of the device prepared in step 7, and a multi-spectral organic photodetector based on RCC material is finally prepared.

[0042] Example 2

[0043] This example provides a multi-spectral organic photodetector based on RCC material, which is different from example 1 only in that the RCC3 solution prepared in step 4 is adjusted to RCC2 solution, specifically 1 mg of RCC2 solid is dissolved in 1 mL of IPA to obtain a uniform solution; then in step 7, the RCC2 solution is spin coated at a rotation speed of 4000 rpm for 30 s, and annealed at 120℃ for 5 min; the remaining steps are the same.

[0044] Comparative Example 1

[0045] This comparative example provides a multi-spectral organic photodetector, which is different from example 1 only in that the step of preparing the RCC3 solution in step 4 is not included; the PTB7-Th-PC 71 The steps of spin coating and annealing the RCC3 solution between the BM solution and the MoO3 solution, and the PTB7-Th:CO i 8DFIC:PC 71 The steps of spin coating and annealing the RCC3 solution between the BM solution and the MoO3 solution, and the PTB7-Th:CO

[0046] Comparative Example 2

[0047] This comparative example provides a multi-spectral organic photodetector, which is different from example 1 only in that the step of preparing the RCC3 solution in step 4 is not included; the PTB7-Th-PC Figure 8 As shown in the structure, it comprises a metal electrode (cathode), a carrier selective transmission layer, a BHJ active layer, an electron transport layer, and a transparent conductive substrate (anode) arranged in sequence from bottom to top. The BHJ active layer is an organic material PIF and a non-fullerene acceptor material IDFBR, ITIC-4F, the material of the metal electrode (cathode) is Ag, the material of the electron transport layer is a good conductive n-type semiconductor material, specifically ZnO, and the transparent conductive substrate is a transparent conductive glass, specifically an ITO substrate.

[0048] The preparation method of the multi-spectral organic photodetector provided in this comparative example comprises the following steps:

[0049] Step 1. Clean the ITO substrate, use detergent and dust-free cloth to wipe, clean in distilled water, acetone and isopropanol in turn for 30 min, then blow dry, then expose the cleaned ITO / glass substrate to ultraviolet (UV) ozone treatment for 15 min.

[0050] Step 2. Prepare ZnO solution: mix 13wt% ZnO nanoparticle aqueous dispersion with deionized water, IPA at a volume ratio of 1:2:2.

[0051] Step 3. Clean the glass substrate, dip deionized water or ethanol with a dust-free cloth or laboratory special wiping paper, gently wipe the surface, remove visible dust or stains, clean in distilled water, acetone and isopropanol in turn for 5-10 min, then blow dry.

[0052] Step 4. Dissolve the organic material PIF and the non-fullerene acceptor material IDFBR in chlorobenzene with a concentration of 20g / L respectively, and stir in a nitrogen-filled glove box for at least 12h, to prepare a uniform solution.

[0053] Step 5. First prepare a MoO3 thin film on the original substrate, and then coat a polymer support layer PMMA.

[0054] Step 6. On the ITO substrate treated in step 1, spin-coat and anneal the solutions prepared in steps 2-5 in turn, specifically: the spin-coating conditions of ZnO solution are 2500 rpm for 50 s, then anneal at 500°C with tin paper for 60 min; use a piezoelectric inkjet printing system to deposit the active layer, configure a 16-channel print head with a volume of 10pL, and the working temperature is constant at 27°C, and inkjet print PIF; separate the MoO3 thin film by etching or mechanical peeling, and dissolve the support layer with acetone, then anneal at low temperature 150°C. Further, 5 electron transport layer, BHJ active layer, hole transport layer are prepared on the ITO substrate in turn.

[0055] Step 7. Evaporate a 80nm thick silver electrode layer on the surface of the device prepared in step 7, to finally obtain a multi-spectrum organic photodetector.

[0056] Comparative Example 3

[0057] This comparative example provides a multi-spectrum organic photodetector, which is different from Comparative Example 2 only in that the non-fullerene acceptor material IDFBR in step 4 is replaced by ITIC-4F.

[0058] Comparative Example 4

[0059] This comparative example provides a multi-spectrum organic photodetector, which is different from Comparative Example 2 only in that:

[0060] Step 4 was changed to dissolve B / G / R selective polymer (e.g. PTB7-Th, P3HT, FST2, 30 mg each) in 10 mL chloroform, respectively. 30 mL deionized water containing 100 mg CTAB was added, and after magnetic stirring for 5 min, ultrasonic treatment was performed for 1 min (power 100 W) until the solution was uniform. Evaporate chloroform at 65℃ to form a water-based colloidal solution. Dialysis overnight using a dialysis bag (MWCO: 12-14 kDa).

[0061] The inkjet printing step in step 8 was changed to an O2 plasma etching step for 5 min at a power of 50 W with a metal mask covering the target area.

[0062] Table 1 Performance test results of the organic photodetectors prepared in Examples 1-2 and Comparative Examples 1-4

[0063]

[0064] The performance test results of the organic photodetectors prepared in Examples 1-2 and Comparative Examples 1-4 are shown in Table 1. Through comparative analysis, Examples 1 and 2 using RCC materials exhibit significant performance advantages in the multi-spectral organic photodetector. Compared with Comparative Example 1 (dark current density as high as 4.96×10 -6 A / cm 2 ), the dark current densities of Examples 1 and 2 are reduced to 2.34×10 -8 A / cm2 and 2.43×10 -8 A / cm 2 , respectively, with a reduction of up to 50%, while the noise current is as low as 0.56×10 -14 A·Hz -1 / 2 , which is nearly 50% lower than that of the comparative example. The RCC material induces the ordered stacking of organic active layer molecules through van der Waals forces, effectively passivates interface defects, and reduces the trap state density to 10 16 cm -3 Below, the non-radiative recombination of carriers is greatly suppressed. This optimization enables the detection rate (D*) of Examples 1 and 2 to reach 8.22×10 13 Jones and 7.81×10 13 Jones, close to the order of 10 14 Jones, far exceeding the 1.1×10 10 Jones of Comparative Example 2 and the 6.9×10 10Moreover, the embodiments still maintain the responsivity of 130 mA / W and 95 mA / W in the visible (380-750 nm) and near-infrared (750-1050 nm) wavebands, balancing the wide-spectrum detection and high-sensitivity characteristics. Although Comparative Examples 3 and 4 exhibit higher responsivity (229-287 mA / W) in a narrow spectrum (e.g., 600-800 nm), the detection rate is significantly reduced (<10 12 Jones), which demonstrates the core advantage of the RCC material in balancing wide-spectrum response and low noise. This technology provides a high-stability, low-dark-current solution for multispectral imaging and weak-light detection, and in the future, performance limits can be broken through by further reducing trap density and optimizing energy band design.

[0065] In summary, the multispectral organic photodetector based on the RCC material proposed in Embodiment 1 and Embodiment 2 can effectively passivate the interface defects of the organic active light-absorbing layer, reduce the dark current of the device, improve the photoelectric conversion efficiency, and ensure the stability of the device under the premise of ensuring the spectral response range.

Claims

1. A high-performance, multi-spectral organic photodetector based on caged molecular passivation, characterized in that: It includes a metal electrode, an electron transport layer, a rear end BHJ layer, a first cage molecule non-contact passivation layer, a carrier selective transmission layer, a second cage molecule non-contact passivation layer, a front end BHJ layer, an electron transport layer and a transparent conductive substrate arranged in sequence from bottom to top; wherein the materials of the first cage molecule non-contact passivation layer and the second cage molecule non-contact passivation layer are Cooper cage molecule materials.

2. The high-performance, multi-spectral organic photodetector based on caged molecule passivation according to claim 1, characterized in that: The materials of the first cage-like molecule non-contact passivation layer and the second cage-like molecule non-contact passivation layer are amine-based molecular cages.

3. The high-performance, multi-spectral organic photodetector based on caged molecule passivation according to claim 1, characterized in that: The material of the first caged molecule non-contact passivation layer and the second caged molecule non-contact passivation layer is RCC1, RCC2 or RCC3.

4. The high-performance, multi-spectral organic photodetector based on caged molecule passivation according to claim 1, characterized in that: The thickness of the first caged molecule non-contact passivation layer and the second caged molecule non-contact passivation layer is 1-8 nm.

5. The high-performance, multi-spectral organic photodetector based on caged molecule passivation according to claim 1, characterized in that: The first cage-like molecule non-contact passivation layer and the second cage-like molecule non-contact passivation layer are prepared by spin coating.

6. The high-performance, multi-spectral organic photodetector based on caged molecule passivation according to claim 1, characterized in that: The front-end BHJ layer is PTB7-Th:PC 71 BM, PM6:BTP-eC9, PM6:L8-Ph, PM6:Y6-BO or m-DTC-Cl-2; the rear BHJ layer is PTB7-Th:CO i 8DFIC:PC 71 BM, PBQx-H-TF / PBTIC-γ-TSe, BTPV-4Cl or PBQ6:PYF-To.

7. The high-performance, multi-spectral organic photodetector based on caged molecule passivation according to claim 1, characterized in that: The material of the carrier selective transmission layer is MoO3, NiO, CuI or CuSCN.

8. The high-performance, multi-spectral organic photodetector based on caged molecule passivation according to claim 1, characterized in that: The material of the electron transport layer is SnO2, TiO2, ZnO, C 60 One or more of .

9. The high-performance, multi-spectral organic photodetector based on caged molecule passivation according to claim 1, characterized in that: The transparent conductive substrate is transparent conductive glass, and the material of the metal electrode is Au, Ag, Pt or carbon.

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