Ternary organic solar cell based on asymmetric acceptor molecules and preparation method thereof

Abstract

The invention provides a ternary organic solar cell based on asymmetric acceptor molecules and a preparation method thereof, and relates to the field of organic solar cells. The ternary organic solar cell forward device structurally comprises a transparent conductive glass substrate, a hole transport layer, a ternary organic active layer, an electron transport layer and a metal Ag electrode in sequence from bottom to top, wherein the ternary organic active layer comprises a polymer donor PM6, a non-fullerene electron acceptor L8-BO and an asymmetric acceptor BTP-OS. An asymmetric acceptor BTP-OS is selected as a third component, a PM6: L8-BO system is introduced, PM6 serves as a donor material of the ternary organic solar cell, L8-BO serves as an acceptor material, and the crystallinity, molecular orientation and vertical component distribution of a blending system are effectively improved by adding BTP-OS, so that charge recombination is effectively inhibited, and the performance of the ternary organic solar cell is improved. Dissociation and charge extraction of excitons in corresponding devices are improved; by adding BTP-OS, the compatibility between a donor and a host receptor can be adjusted, so that the multi-scale morphology of the blended membrane is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of organic solar cells, in particular to a ternary organic solar cell based on asymmetric receptor molecules and a preparation method thereof. Background Art

[0002] Organic solar cells have the advantages of light weight, low cost, translucency, and solution processing. The active layer of an organic solar cell is composed of a blend of donor and acceptor materials. The light absorption capacity and morphology of the blend film determine the performance of the device. With the development and design of organic photovoltaic materials and the continuous optimization of device processes, the energy conversion efficiency of organic solar cells has developed rapidly, but it still lags behind inorganic solar cells.

[0003] Further improvement of the performance of organic solar cell devices is still limited by large voltage losses, mainly caused by non-radiative recombination. Although non-radiative voltage losses can be suppressed through material structure design, short-circuit current is often sacrificed, making it difficult to achieve improved energy conversion efficiency. In addition, the stability of organic solar cells is also a key consideration and is the key to limiting future commercial applications.

[0004] The ternary strategy is an effective method commonly used to improve device performance. This strategy involves introducing a third component into the main system to broaden light absorption, optimize the blending morphology, or improve exciton dissociation and charge extraction capabilities, thereby improving device performance, and has become a research hotspot in the field of organic photovoltaics. In recent years, relevant literature has reported that the third component has unique advantages in improving energy conversion efficiency, but rarely mentions enhancing device stability. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a ternary organic solar cell based on an asymmetric receptor molecule and a preparation method thereof, which solves the problem of poor stability of organic solar cell devices.

[0006] To achieve the above objectives, the present invention is implemented by the following technical scheme: a ternary organic solar cell based on an asymmetric receptor molecule, wherein the structural layers of the forward device of the ternary organic solar cell are, from bottom to top, a transparent conductive glass substrate, a hole transport layer, a ternary organic active layer, an electron transport layer, and a metal Ag electrode;

[0007] The ternary organic active layer includes a polymer donor PM6, a non-fullerene electron acceptor L8-BO and an asymmetric acceptor BTP-OS;

[0008] The structural formula of the polymer donor PM6 is:

[0009]

[0010] The structural formula of the non-fullerene electron acceptor L8-BO is:

[0011]

[0012] The structural formula of the asymmetric receptor BTP-OS is:

[0013]

[0014] Preferably, the structural hierarchy of the forward device of the ternary solar cell is, from bottom to top, an ITO glass sheet, a PEDOT:PSS hole transport layer, a ternary organic active layer, a PNDIT-F3N electron transport layer, and a metal Ag cathode.

[0015] Preferably, the ternary organic active layer is a bulk heterojunction type PM6:L8-BO:BTP-OS.

[0016] Preferably, the mass ratio of PM6:L8-BO:BTP-OS in the ternary organic active layer is 1:(0-1.2):(0-1.2).

[0017] The method for preparing a ternary organic solar cell based on an asymmetric receptor molecule comprises the following steps:

[0018] S1. First, the ITO glass sheet was ultrasonically treated in detergent + deionized water, deionized water, acetone, and isopropanol in sequence, and then treated in a UV ozone cleaning machine for 15 minutes;

[0019] S2. The PEDOT:PSS solution is formed into a film on an ITO glass sheet by spin coating, and then thermally annealed to form a hole transport layer;

[0020] S3. PM6, PM6:L8-BO and BTP-OS were dissolved in a chloroform solution at a mass ratio of 1:(0-1.2):(0-1.2), heated and stirred in a glove box, and 0.5% by volume of DIO was added 30 minutes before spin coating the active layer, and then spin coated onto the hole transport layer to form a bulk heterojunction active layer;

[0021] S4. FNDIT-F3N is dissolved in a methanol solvent containing 0.5% acetic acid by volume, and the FNDIT-F3N solution is formed into a film on the active layer by spin coating to form an electron transport layer.

[0022] S5. Evaporate a metal Ag electrode onto the FNDIT-F3N electron transport layer.

[0023] Preferably, in the step S2, the rotation speed is 4500-5500 rpm / min, the spin coating time is 30 s; the annealing temperature is 145° C.-150° C., and the annealing time is 20 min.

[0024] Preferably, in the step S3, the concentration of the bulk heterojunction active layer material is 14-16 mg / mL, and the spin coating speed of the bulk heterojunction active layer is 2500-3500 rpm / min.

[0025] Preferably, in the step S4, the concentration of PNDIT-F3N is 0.3-0.8 mg / mL, the spin coating speed is 1500-2500 rpm / min, and the spin coating time is 40 s.

[0026] The present invention provides a ternary organic solar cell based on an asymmetric receptor molecule and a preparation method thereof. It has the following beneficial effects:

[0027] 1. The present invention introduces the PM6:L8-BO system by selecting an asymmetric acceptor BTP-OS as the third component, wherein PM6 is used as the donor material of the ternary organic solar cell, and L8-BO is used as the acceptor material. The addition of BTP-OS effectively improves the crystallinity, molecular orientation and vertical component distribution of the blend system, thereby effectively suppressing charge recombination and improving the dissociation and charge extraction of excitons in the corresponding device; the addition of BTP-OS can adjust the compatibility between the donor and the host acceptor, thereby improving the multi-scale morphology of the blend film; at the same time, the addition of BTP-OS can effectively reduce the energy disorder and non-radiative energy loss of the device, thereby reducing the voltage loss; finally, the addition of BTP-OS improves the energy conversion efficiency of the ternary organic solar cell based on the PM6:L8-BO system. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a diagram of the heterogeneous structure of the forward device structure of the solar cell of the present invention;

[0029] Figure 2 It is a normalized UV-visible light absorption spectrum of the thin film made of PM6, L8-BO and BTP-OS in the solar cell of the present invention;

[0030] Figure 3 The device current (J) of the solar cells based on PM6:L8-BO, PM6:L8-BO:BTP-OS and PM6:BTP-OS in the first, second and fourth embodiments of the present invention is SC )-Voltage(V OC ) curve graph;

[0031] Figure 4This is a graph showing the attenuation curve of the device efficiency of the solar cells prepared in Example 1, Example 2, and Example 4 of the present invention under illumination conditions. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] The donor PM6, the acceptor L8-BO and the asymmetric acceptor molecule BTP-OS were weighed in the mass ratios of PM6:L8-BO:BTP-OS of 1:1.2:0.0, 1:1.0:0.2, 1:0.8:0.4 and 1:0.0:1.2 respectively for preparing bulk heterostructure devices.

[0034] Embodiment 1:

[0035] Reference Figure 1-4 The embodiment of the present invention provides a ternary organic solar cell based on an asymmetric receptor molecule. The structural hierarchy of the forward device of the ternary organic solar cell is, from bottom to top, an ITO glass sheet, a PEDOT:PSS hole transport layer, a ternary organic active layer, a PNDIT-F3N electron transport layer, and a metal Ag cathode. Figure 1 As shown, 1 is a metal Ag cathode, 2 is a PNDIT-F3N electron transport layer, 3 is a ternary organic active layer, 4 is a PEDOT:PSS hole transport layer, and 5 is an ITO glass sheet;

[0036] The ternary organic active layer includes a polymer donor PM6, a non-fullerene electron acceptor L8-BO, and an asymmetric acceptor BTP-OS;

[0037] The structural formula of polymer donor PM6 is:

[0038]

[0039] The structural formula of the non-fullerene electron acceptor L8-BO is:

[0040]

[0041] The structural formula of the asymmetric receptor BTP-OS is:

[0042]

[0043] The method for preparing a ternary organic solar cell based on an asymmetric receptor molecule comprises the following steps:

[0044] S1. Treat the ITO glass sheet with ultrasonic in detergent + deionized water, deionized water, acetone, and isopropanol in sequence, and then treat it in a UV-ozone cleaning machine for 15 minutes.

[0045] S2. The PEDOT:PSS solution is formed into a film on the ITO glass sheet by spin coating, and then thermal annealing is performed to form a hole transport layer.

[0046] S3. PM6, PM6:L8-BO and BTP-OS were dissolved in chloroform solution at a mass ratio of 1:1.2:0, heated and stirred in a glove box, and 0.5% by volume of DIO was added 30 minutes before spin coating the active layer, and then spin coated onto the hole transport layer to form a bulk heterojunction active layer.

[0047] S4. FNDIT-F3N is dissolved in a methanol solvent containing 0.5% acetic acid by volume, and the FNDIT-F3N solution is formed into a film on the active layer by spin coating to form an electron transport layer.

[0048] S5. Evaporate a metal Ag electrode onto the FNDIT-F3N electron transport layer.

[0049] Embodiment 2:

[0050] A control device was prepared according to the method of Example 1, except that the mass ratio of the active layer donor PM6, acceptor L8-BO, and asymmetric acceptor molecule BTP-OS of the bulk heterojunction device was 1:1.0:0.2.

[0051] Embodiment three:

[0052] A control device was prepared according to the method of Example 1, except that the mass ratio of the active layer donor PM6, acceptor L8-BO, and asymmetric acceptor molecule BTP-OS of the bulk heterojunction device was 1:0.8:0.4.

[0053] Embodiment 4:

[0054] A control device was prepared according to the method of Example 1, except that the mass ratio of the active layer donor PM6, acceptor L8-BO, and asymmetric acceptor molecule BTP-OS of the bulk heterojunction device was 1:0.0:1.2.

[0055] The photovoltaic performance test was performed on the devices prepared in Examples 1 to 4:

[0056] The light source is AM1.5G, and the light intensity is 100mW / cm 2 The intensity of the light source is tested and calibrated by a standard silicon cell, and the test instrument is a Keithley 2400 source meter.

[0057] The (JSC)-voltage (VOC) curves of the devices of Comparative Examples 1 to 4 were obtained by testing, as shown in FIG. Figure 3 shown.

[0058] The performance of the devices prepared in Examples 1 to 4 obtained by testing is shown in the following table: including open circuit voltage (VOC), short circuit current (JSC), fill factor and power conversion efficiency (PCE), where:

[0059] PCE=VOC*JSC*FF / Pin (Pin is the intensity of incident light)

[0060]

[0061] According to the table above, when the asymmetric receptor molecule BTP-OS is added to the PM6:L8-BO binary system, as the BTP-OS content gradually increases, the open circuit voltage, fill factor, and short circuit current density are all greatly affected. When PM6:L8-B0:BTP-OS is 1:1.0:0.2, the open circuit voltage of the bulk heterojunction device reaches 0.898V, and the short circuit current density reaches a maximum of 27.01mA cm -2 , the filling factor reached 79.72%, and the energy conversion efficiency reached 19.34%, indicating that the construction of the PM6:L8-BO:BTP-OS ternary system successfully improved the performance of the device.

[0062] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A ternary organic solar cell based on an asymmetric acceptor molecule, characterized in that: The structural layers of the forward device of the ternary organic solar cell are, from bottom to top, a transparent conductive glass substrate, a hole transport layer, a ternary organic active layer, an electron transport layer, and a metal Ag electrode; The ternary organic active layer includes a polymer donor PM6, a non-fullerene electron acceptor L8-BO and an asymmetric acceptor BTP-OS; The structural formula of the polymer donor PM6 is: The structural formula of the non-fullerene electron acceptor L8-BO is: The structural formula of the asymmetric receptor BTP-OS is:

2. The ternary organic solar cell based on asymmetric acceptor molecules according to claim 1, characterized in that: The structural levels of the forward device of the ternary solar cell are, from bottom to top, an ITO glass sheet, a PEDOT:PSS hole transport layer, a ternary organic active layer, a PNDIT-F3N electron transport layer, and a metal Ag cathode.

3. The ternary organic solar cell based on asymmetric acceptor molecules according to claim 1, characterized in that: The ternary organic active layer is a bulk heterojunction type PM6:L8-BO:BTP-OS.

4. The ternary organic solar cell based on asymmetric acceptor molecules according to claim 2, characterized in that: The mass ratio of PM6:L8-BO:BTP-OS in the ternary organic active layer is 1:(0-1.2):(0-1.2).

5. The method for preparing a ternary organic solar cell based on an asymmetric receptor molecule according to claim 1, characterized in that: The following steps are involved: S1. First, the ITO glass sheet was ultrasonically treated in detergent + deionized water, deionized water, acetone, and isopropanol in sequence, and then treated in a UV ozone cleaning machine for 15 minutes; S2. The PEDOT:PSS solution is formed into a film on an ITO glass sheet by spin coating, and then thermally annealed to form a hole transport layer; S3. PM6, PM6:L8-BO and BTP-OS were dissolved in a chloroform solution at a mass ratio of 1:(0-1.2):(0-1.2), heated and stirred in a glove box, and 0.5% by volume of DIO was added 30 minutes before spin coating the active layer, and then spin coated onto the hole transport layer to form a bulk heterojunction active layer; S4. FNDIT-F3N is dissolved in a methanol solvent containing 0.5% acetic acid by volume, and the FNDIT-F3N solution is formed into a film on the active layer by spin coating to form an electron transport layer. S5. Evaporate a metal Ag electrode onto the FNDIT-F3N electron transport layer.

6. The method for preparing a ternary organic solar cell based on an asymmetric receptor molecule according to claim 5, characterized in that: In the step S2, the rotation speed is 4500-5500 rpm / min, the spin coating time is 30 s; the annealing temperature is 145° C.-150° C., and the annealing time is 20 min.

7. The method for preparing a ternary organic solar cell based on an asymmetric receptor molecule according to claim 5, characterized in that: In the step S3, the concentration of the bulk heterojunction active layer material is 14-16 mg / mL, and the spin coating speed of the bulk heterojunction active layer is 2500-3500 rpm / min.

8. The method for preparing a ternary organic solar cell based on an asymmetric receptor molecule according to claim 5, characterized in that: In the step S4, the concentration of PNDIT-F3N is 0.3-0.8 mg / mL, the spin coating speed is 1500-2500 rpm / min, and the spin coating time is 40 s.

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