All-polymer stretchable fiber-like solar cells and methods of making the same

Abstract

The application relates to an all-polymer stretchable fiber-like solar cell and a preparation method thereof. According to the technical scheme of the application, the mechanical tensile property of an active layer can be further improved, and the tensile property of a device is further improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photovoltaic devices, in particular, the present application relates to a full polymer stretchable fiber-like solar cell and a preparation method thereof. BACKGROUND

[0002] Flexible fiber-like organic solar cells (FOSC) have the advantages of safety, light weight, flexibility, and full solid structure, and can not only generate electricity but also be integrated with clothes and textiles, showing great application potential in wearable devices. In practical applications, in addition to meeting the basic requirements of high efficiency, flexibility, and wearability, fiber-like solar cells also need to have stretchability so that they can adapt to different degrees of deformation during wearing.

[0003] CN115513385A discloses a stretchable fiber-like solar cell that can maintain 90% of the initial performance under a tensile strain of 30%, however, due to the brittleness of small molecules, the mechanical properties of polymer donor and non-fullerene small molecule acceptor blending systems are usually insufficient, and the performance decreases significantly when the tensile strain exceeds 40%, so there is still a large space for improvement in the tensile properties of the device. SUMMARY

[0004] Based on previous research, the inventors of the present application found that, compared with small molecule acceptors, polymer acceptors not only can maintain similar photoelectric properties as small molecule acceptors, but also have more excellent mechanical tensile properties, and on this basis, the present application was completed.

[0005] An object of the present application is to provide a full polymer stretchable fiber-like solar cell, which comprises:

[0006] a fiber-like stretchable electrode composed of an elastic fiber and an electrode layer coated on the elastic fiber; wherein the elastic fiber is made of a material selected from TPU, SBS, SEBS, SIS, PDMS, EPDM, POE, TPE, TPV, TPE, PPE and TREE, and the electrode layer is made of a material selected from ITO, Ag NPs, Ag NWs, Au NPs, Au NWs, Cu NWs, Cu NPs, Cu NWs, carbon nanotubes, graphene, carbon nanosheets and PEDOT:PSS; preferably, the elastic fiber is made of TPU, and the electrode layer is made of ITO;

[0007] an electron transport layer coated on the outside of the fiber-like inner layer stretchable electrode, made of a material selected from PFN-Br, PFN, PFQ-Br and PFN-2TNDI; preferably made of PFN-Br;

[0008] an organic photovoltaic material light absorbing layer coated on the outside of the electron transport layer, made of a material selected from the group consisting of PM6:PY-IT, PM6:PYDT-3F, PTQ10:PY-IT, PCE10:N2200, PM6:J71:PY-IT, PM6:PTQ10:PY-IT and PM6:PY-IT:PYF-IT; preferably made of PM6:PY-IT;

[0009] a hole transport layer coated on the outside of the electron transport layer, made of a material selected from the group consisting of PEDOT:PSS, PTAA, poly-TPD, c-OTPD, TQ1 and P3HT; preferably made of PEDOT:PSS;

[0010] an outer electrode wound as a filament on the outside of the hole transport layer, made of a material selected from the group consisting of flexible carbon nanotube filament, silver filament, copper filament or elastic conductive fiber.

[0011] According to one embodiment of the present application, wherein,

[0012] The organic photovoltaic material light absorbing layer further comprises an elastomer additive selected from the group consisting of SEBS, SBS, SIS, PDMS, EPDM and POE, and the amount of the elastomer additive added is 0wt%-30wt% based on the amount of the organic photovoltaic material light absorbing layer. Preferably, the elastomer additive is SEBS, and the amount of the elastomer additive added is 0.5wt%-30wt%, more preferably 5wt% to 30wt%.

[0013] According to one embodiment of the present application, wherein the battery maintains photoelectric conversion performance of 80% or more under a tensile strain of 60%.

[0014] According to one embodiment of the present application, wherein the battery maintains photoelectric conversion performance of 80% or more under a tensile strain of 30% for more than 1000 times of repetition.

[0015] Wherein, the photoelectric conversion performance refers to energy conversion efficiency.

[0016] The energy conversion efficiency is calculated by the following method: PCE = P max / P in = (V OC × J SC × FF) / P in The energy conversion efficiency is measured by using a solar simulator combined with a Keithley 2400 source meter instrument.

[0017] According to one embodiment of the present application, wherein the battery is prepared by pre-stretching 10-100%.

[0018] According to one embodiment of the present application, the battery is prepared by the following method:

[0019] S1) cleaning and plasma treating the elastic fiber, stretching the treated elastic fiber by 10-100%, coating an electrode layer dispersion liquid on the treated elastic fiber, and then stopping the stretching to restore the original length to obtain a fibrous inner layer stretchable electrode;

[0020] The cleaning treatment includes ultrasonic cleaning with a surfactant, a detergent;

[0021] The plasma treatment includes oxygen plasma treatment for 10 seconds to 2 minutes;

[0022] S2) stretching the fibrous inner layer stretchable electrode by 10-100%, and coating an electron transport layer material on the fibrous inner layer stretchable electrode to obtain an electron transport layer;

[0023] S3) coating an organic photovoltaic material light absorbing layer on the electron transport layer to further obtain an organic photovoltaic material light absorbing layer;

[0024] S4) coating a hole transport layer material on the organic photovoltaic material light absorbing layer to obtain a hole transport layer; and then stopping the stretching to restore the original length;

[0025] S5) winding an outer electrode material on the hole transport layer to obtain a full-polymer stretchable fibrous solar cell,

[0026] wherein the elastic fiber, the electrode layer, the electron transport layer, the organic photovoltaic material light absorbing layer, the hole transport layer, and the outer electrode are the same as described above.

[0027] According to another aspect of the present application, a preparation method of the full-polymer stretchable fibrous solar cell is provided.

[0028] According to one embodiment of the present application, wherein,

[0029] In step S1), the diameter of the elastic fiber is 0.1-0.8 mm, the coating film speed is 100-5000 mm / min, the concentration of the electrode layer dispersion liquid is 1-20 mg / mL, and the coating film is performed 1-10 times.

[0030] According to one embodiment of the present application, wherein,

[0031] In step S2), the coating film speed of the electron transport layer is 100-5000 mm / min, and the concentration of the electron transport layer material is 1-50 mg / mL;

[0032] In step S3), the coating speed of the organic photovoltaic material light-absorbing layer is 100-5000 mm / min, and the concentration of the organic photovoltaic material light-absorbing layer is 1-50 mg / mL.

[0033] In step S4), the coating speed of the hole transport layer is 100-5000 mm / min.

[0034] Preferably, in step S4), the hole transport layer solution is diluted to 10%-80% of the original concentration (i.e. the concentration of the commercially available solution).

[0035] According to one embodiment of the present application, wherein,

[0036] Further comprising between step S4) and step S5):

[0037] S4') annealing the fiber obtained in step S4) at 80-150°C for 1-10 minutes.

[0038] The intrinsically stretchable fiber-shaped organic solar cell device prepared based on the present technology has a high energy conversion efficiency, which can reach 3.88%. The device has good stretchability, and can retain 97.3%, 95.6%, 91.8% and 85% of the initial efficiency under 20%, 40%, 50% and 60% tensile strain, respectively. The pre-stretching strategy can increase the maximum tensile strain that the device can withstand from about 50% to about 80%. The device has good durability and stability, and can maintain more than 80% of the photoelectric conversion performance after repeated stretching for more than 1000 times under a tensile strain of 30%.

[0039] On this basis, further adding 0-30 wt% of a third component elastomer additive SEBS to the blending solution system of the active layer to improve the tensile properties of the film, and further increasing the maximum tensile strain that the device can withstand to about 100%. The device with SEBS has more excellent stability and can maintain higher initial photovoltaic performance after long-term storage and long-term illumination.

[0040] Advantages

[0041] The all-polymer stretchable fiber-shaped solar cell of the present application can further improve the mechanical tensile properties of the active layer and further improve the tensile properties of the device. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 The structure of the all-polymer intrinsically stretchable fiber-shaped solar cell device.

[0043] Figure 2 The photovoltaic performance of the all-polymer intrinsically stretchable fiber-shaped solar cell.

[0044] Figure 3 Tensile properties of intrinsic stretchable fiber-like organic solar cells based on small molecule and all-polymer systems.

[0045] Figure 4 Cyclic tensile stability of intrinsic stretchable fiber-like organic solar cells based on small molecule and all-polymer systems.

[0046] Figure 5 Film morphology of active layer films with different SEBS additive amounts under 30% tensile strain.

[0047] Figure 6 Tensile properties of fiber battery devices with SEBS elastomer introduced (without pre-stretching treatment), which can withstand a maximum tensile strain of 100%.

[0048] Figure 7 Stability of fiber battery devices with SEBS elastomer introduced, which can maintain higher photovoltaic performance. DETAILED DESCRIPTION

[0049] To enable persons having ordinary knowledge in the art to understand the features and effects of the present application, the following is a general description and definition of the terms and phrases mentioned in the specification and the scope of the application. Unless otherwise specified, all technical and scientific words used in the text have the usual meaning understood by those skilled in the art of the present application, and in case of conflict, the definition in the specification shall prevail.

[0050] In the present application, each organic photovoltaic material used is purchased from Nanjing Zhiyan unless otherwise specified, electrode materials such as ITO NPs and Ag NWs are purchased from Bestnano, PEDOT:PSS is purchased from Germany Heraeus Clevios, and the solar simulator used is purchased from Newport.

[0051] The meanings of the terms used in this text are as follows:

[0052] NWs: nanowires;

[0053] NPs: nanoparticles;

[0054] ITO: indium tin oxide;

[0055] PFN-Br: poly[(9,9-di(3'-(N,N-dimethylamino)propyl)fluorenyl-2,7-diyl)-ALT-[(9,9-di-n-octylfluorenyl 2,7-diyl)-bromine;

[0056] PM6: poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-fluoro)thiophene-2-yl)-benzo[1,2-B:4,5-B']dithiophene))-ALT-(5,5-(1',3'-di-2-thiophene-5',7'-bis(2-ethylhexyl)benzo[1',2'-C:4',5'-C']dithiophene-4,8-diketone;

[0057] PY-IT: poly 2-{2-[(Z)-(10-{[(2Z)-1-(dicyanomethylidene)-3-oxo-5-(thiophen-2-yl)-2,3-dihydro-1H-inden-2-ylidene]methyl}-12,13-bis(2-octyldodecyl)-3,9-heneicosyl[1,2,5]thiadiazolo[4,3-e]thieno[2',3':4,5]thieno[3,2-b]thieno[2",3":4',5']thieno[2',3':4,5]pyrrolo[3,2-g]indol-2-yl)methylidene]-3-oxo-2,3-dihydro-1H-indenylidene}propanedinitrile;

[0058] Y6: 12,13-bis(2-ethylhexyl)-3,9-biheneicosyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2",3":4',5']thieno[2',3':4,5]pyrrolo[3,2-g]thieno[2',3':4,5]thieno[3,2-b]indole-2,10-di(5,6-difluoro-3-(dicyanomethylene)indene-1-one);

[0059] SEBS: styrene-ethylene / butylene-styrene block copolymer;

[0060] PEDOT:PSS: poly(3,4-ethylenedioxythiophene):polystyrene sulfonate;

[0061] Example 1: Preparation of stretchable fiber-like organic solar cells

[0062] (1) Configuration of each functional coating solution

[0063] Ag NWs were dispersed in ethanol solution with a concentration of 10 mg / mL; ITO NPs were dispersed in isopropanol solution with a concentration of 1 wt%, and were physically dispersed before each use; PFN-Br was dissolved in methanol with a concentration of 20 mg / mL; PM6 and PY-IT were both dissolved in chloroform solvent, and the two organic semiconductor materials were mixed at a mass ratio of 1:1, with a total mass concentration of the solution being 12 mg / mL, and no third component SEBS elastomer was added, i.e., the amount of SEBS elastomer added was 0 wt%. The PEDOT:PSS solution was diluted to 50% of the original concentration (i.e., the concentration of the commercially available solution).

[0064] (2) Preparation of intrinsic stretchable fiber-based electrode and counter electrode

[0065] Carbon nanotube filaments with a diameter of 0.1 mm or elastic conductive fibers were used as the counter electrode. TPU polyurethane elastic fibers with a diameter of 0.5 mm were used as the core of the intrinsic stretchable fiber electrode, and were ultrasonically cleaned in a deionized water solution containing a cleaning agent, deionized water, and an ethanol solution for 10 min, respectively. After cleaning, the TPU fibers were dried in air or a nitrogen atmosphere; the surface of the TPU fibers was subjected to plasma treatment to improve its wettability; the treated TPU fibers were fixed on a film coating machine, and a tensile strain of 25% was applied (hereinafter referred to as pre-stretching); subsequently, high-conductivity AgNWs and ITO NPs were uniformly coated on the surface of the TPU fibers by mechanical coating, and the coating speed was set to 1000 mm / min; the above steps were repeated 4 times to ensure sufficient conductivity; and after each coating was completed, the sample was naturally dried in a room temperature environment.

[0066] (3) Preparation of intrinsic stretchable fiber-shaped organic solar cell

[0067] Based on the above-prepared intrinsic stretchable conductive fiber electrode, an intrinsic stretchable fiber battery was prepared. First, the conductive fiber base electrode was subjected to a 25% pre-stretching treatment; a PFN-Br electron transport layer was prepared, and an electron transport layer precursor solution was uniformly coated at a speed of 1000 mm / min, and the solution concentration was 20 mg / mL; a PM6:PY-IT:SEBS ternary organic photovoltaic material (in this embodiment 1, the SEBS content was 0) was uniformly coated at a coating speed of 5000 mm / min; a material such as PEDOT:PSS was used as a hole transport layer, and the hole transport layer was coated at a coating speed of 1000 mm / min, to complete the preparation of the full-polymer FOSC working electrode; finally, a flexible carbon nanotube filament was used as the counter electrode, and was wound on the working electrode at a pitch of 1 mm, to form a biaxial device structure, as shown in Figure 1 .

[0068] Embodiments 2-6

[0069] Embodiments 2-6 of the intrinsic stretchable fiber-shaped organic solar cell were prepared in the same manner as in embodiment 1, except that in "(1) Configuration of each functional coating solution", the amount of SEBS elastomer was modified to 0.5 wt%, 2 wt%, 5 wt%, 10 wt%, and 30 wt%, respectively.

[0070] Embodiments 7-8

[0071] Example 7-8 were prepared in the same manner as Example 1 except that in "(1) Preparation of each functional coating solution", the amount of SEBS elastomer was modified to 5 wt% and 30 wt% respectively, and in "(2) Preparation of intrinsic stretchable fiber-based anode and counter electrode", no pre-stretching was performed.

[0072] Comparative Example 1

[0073] Example 7-8 were prepared in the same manner as Example 1 except that in "(1) Preparation of each functional coating solution", the amount of SEBS elastomer was modified to 5 wt% and 30 wt% respectively, and in "(2) Preparation of intrinsic stretchable fiber-based anode and counter electrode", no pre-stretching was performed.

[0074] Comparative Example 2

[0075] Example 7-8 were prepared in the same manner as Example 1 except that in "(1) Preparation of each functional coating solution", the amount of SEBS elastomer was modified to 5 wt% and 30 wt% respectively, and in "(2) Preparation of intrinsic stretchable fiber-based anode and counter electrode", no pre-stretching was performed.

[0076] The components and preparation methods of Examples 1-8 and Comparative Examples 1-2 are shown in Table 1 below.

[0077] Table 1

[0078]

[0079]

[0080] Experimental Examples

[0081] Characterization of stretchable performance and photovoltaic performance of intrinsic stretchable fiber-based organic solar cells

[0082] The stretchable performance of the stretchable fiber-based and fiber-shaped solar cells was characterized using a high-precision numerical control sliding table with clamps. The two ends of the fiber were fixed on the two clamps, respectively. Through the program control system, the corresponding program was set to accurately measure the stretchable performance under different conditions, such as single strain, multiple cycle strain, and incremental strain, etc. The resistance change of the fiber electrode during the stretching process was characterized in real time by Keithley 2400 digital source meter. Using a solar simulator (Newport, M94043A) to simulate AM1.5G, 100 mW / cm 2 The photovoltaic performance of the battery was tested under the light environment combined with Keithley 2400 digital source meter to obtain the J-V curve of the battery. Similarly, the photovoltaic test system combined with the stretchable performance test system can characterize the photovoltaic performance of the fiber-shaped battery in real time during the stretching process, including J-V curve and photocurrent curve.

[0083] The intrinsically stretchable fiber organic solar cells prepared by Example 1 have excellent photovoltaic performance, with energy conversion efficiency as high as 3.81%, as shown in Figure 2 .

[0084] The cells prepared by Example 1 and Comparative Example 1 are tested. The prepared fiber-like organic solar cells have excellent photovoltaic performance that can be maintained under different tensile strains, and the real-time detection of the change in photo-generated current can directly reflect the change in photovoltaic performance of the fiber device during continuous stretching. Within a strain range of 50%, the device photo-generated current remains basically unchanged, while the photo-generated current of the small molecule acceptor system rapidly decays under a strain of 30%, as shown in Figure 3 , the device is pre-stretched by 25%.

[0085] The cells prepared by Example 1 and Comparative Example 1 are tested. The device has good mechanical stability, and after repeated stretching for 1000 times under a tensile strain of 30%, the device can still maintain more than 80% of the initial performance, while the small molecule system can only maintain 30% of the initial performance after 100 cycles, as shown in Figure 4 .

[0086] The thin film morphology of the active layer film with different SEBS addition amounts in Examples 1-6 under a tensile strain of 30% is tested, and a Zeiss scanning electron microscope is used for observation. The results are shown in Figure 5 . It can be seen from Figure 5 that the further introduction of the third component SEBS improves the stretchability of the active layer film, and the film with an SEBS addition amount of 30% has significantly improved tensile performance and produces the least cracks under the same tensile strain (30%).

[0087] The cells of Example 1 and Examples 7-8 are further measured. Compared with the small molecule acceptor system, the introduction of SEBS can further significantly improve the maximum tensile strain that the device can withstand, and the maximum tensile strain that the device can withstand can reach 100%, as shown in Figure 6 .

[0088] The cells prepared by Example 1 and 4, and Comparative Example 1 and 2 are tested. The introduction of SEBS can also improve the stability of the device, which can maintain higher photovoltaic performance after long-term storage in an air environment, and is not only suitable for small molecule systems, but also for all-polymer systems, as shown in Figure 7 .

Claims

1. A fully polymer stretchable fiber-like solar cell, the cell comprising: a fiber-like stretchable electrode consisting of an elastic fiber and an electrode layer coated on the elastic fiber; wherein the elastic fiber is made of a material selected from TPU, SBS, SEBS, SIS, PDMS, EPDM, POE, TPE, TPV, TPE, PPE and TREE, and the electrode layer is made of a material selected from ITO, Ag NPs, Ag NWs, Au NPs, Au NWs, Cu NWs, Cu NPs, Cu NWs, carbon nanotubes, graphene, carbon nanosheets and PEDOT:PSS; an electron transport layer coated on the outside of the fiber-like inner layer stretchable electrode, made of a material selected from PFN-Br, PFN, PFQ-Br and PFN-2TNDI; an organic photovoltaic material light absorbing layer coated on the outside of the electron transport layer, made of a material selected from PM6:PY-IT, PM6:PYDT-3F, PTQ10:PY-IT, PCE10:N2200, PM6:J71:PY-IT, PM6:PTQ10:PY-IT and PM6:PY-IT:PYF-IT; a hole transport layer coated on the outside of the electron transport layer, made of a material selected from PEDOT:PSS, PTAA, poly-TPD, c-OTPD, TQ1 and P3HT; an outer layer electrode wound as a filament on the outside of the hole transport layer, made of a material selected from flexible carbon nanotube filaments, silver filaments or copper filaments, wherein the cell maintains photoelectric conversion performance of 80% or more under a tensile strain of 60%, the cell maintains photoelectric conversion performance of 80% or more under a tensile strain of 30% for 1000 times or more, and the cell is prepared by pre-stretching 10-100%.

2. The cell according to claim 1, wherein the organic photovoltaic material light absorbing layer further comprises an elastomer additive selected from SEBS, SBS, SIS, PDMS, EPDM and POE, and the amount of the elastomer additive added is 0 wt%-30 wt% based on the amount of the light absorbing layer organic photovoltaic material.

3. A method for preparing the cell according to claim 1 or 2, the method comprising: S1) cleaning and plasma treating the elastic fiber, stretching the treated elastic fiber by 10-100%, and coating an electrode layer dispersion on the treated elastic fiber, then stopping the stretching and allowing it to return to the original length to obtain a fiber-like stretchable electrode; the cleaning treatment comprises ultrasonic cleaning with a surfactant, a detergent; the plasma treatment comprises oxygen plasma treatment for 10 seconds to 2 minutes; S2) stretching the fiber-like stretchable electrode by 10-100%, and coating an electron transport layer material on the fiber-like stretchable electrode to obtain an electron transport layer; S3) coating an organic photovoltaic material light absorbing layer on the electron transport layer to further obtain an organic photovoltaic material light absorbing layer; S4) coating the hole transport layer material on the organic photovoltaic material light absorbing layer to obtain a hole transport layer; then stop stretching to restore the original length; S5) winding the outer electrode material on the hole transport layer to obtain a full polymer stretchable fiber-like solar cell, Wherein, the elastic fiber, the electrode layer, the electron transport layer, the organic photovoltaic material light absorbing layer, the hole transport layer, and the outer electrode are the same as those in claim 1.

4. The preparation method of claim 3, wherein, In step S1), the diameter of the elastic fiber is 0.1-0.8 mm, the coating film speed is 100-5000 mm / min, the concentration of the electrode layer dispersion liquid is 1-20 mg / mL, and the coating film is performed 1-10 times.

5. The preparation method of claim 3, wherein, In step S2), the coating film speed of the electron transport layer is 100-5000 mm / min, and the concentration of the electron transport layer material is 1-50 mg / mL; In step S3), the coating film speed of the organic photovoltaic material light absorbing layer is 100-5000 mm / min, and the concentration of the organic photovoltaic material light absorbing layer is 1-50 mg / mL; In step S4), the coating film speed of the hole transport layer is 100-5000 mm / min.

6. The preparation method of claim 3, wherein, Further comprising between step S4) and step S5): S4') annealing the fiber obtained in step S4) at 80-150°C for 1-10 minutes.

Images