Preparation method of lignin derivative modified photo-anode, counter electrode and electrolyte and assembled solar cell

Abstract

The invention discloses a preparation method for modifying a photo-anode, a counter electrode and an electrolyte by using a lignin derivative and application of an assembled solar cell, and the method comprises the following steps: dissolving alkali lignin in ethanol, ultrasonically stirring, centrifuging, and taking supernate to obtain a lignin / ethanol solution; the preparation method comprises the following steps: dissolving lignin, titanium dioxide, ethyl cellulose and alpha-terpilenol in a lignin / ethanol solution, and ultrasonically stirring to obtain the photo-anode material. Sodium lignin sulfonate is dissolved in the EDOT aqueous solution to serve as an electro-deposition solution, and the counter electrode is prepared through constant-current electro-deposition. The preparation method comprises the following steps: dissolving alkali lignin in acetonitrile, and ultrasonically stirring valeronitrile, 1-methyl-3-propyl imidazolium iodide, guanidine cyanosulfate, iodine and 4-tert-butylpyridine to obtain the AL / I electrolyte. The dye-sensitized solar cell prepared by assembling the photo-anode, the counter electrode and the electrolyte has the advantages of high photoelectric conversion efficiency, low cost and the like, and has a good application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of solar cells, specifically to the technical field of dye-sensitized solar cells (DSSCs), and in particular to a preparation method of a lignin derivative-modified photoanode, a counter electrode and an electrolyte, and an assembled solar cell. Background Art

[0002] Dye-sensitized solar cells (DSSCs) use biomass materials as electrode materials, which are low-cost and easy to obtain. Due to its low cost and non-toxic properties, it has attracted much attention in the third generation of solar cells.

[0003] On the one hand, the traditional photoanode, counter electrode and electrolyte assembly DSSCs reported so far still have problems such as poor structural fine-tuning and the need to improve the photoelectric conversion efficiency. On the other hand, although the method of preparing electrode materials by carbonization of lignin derivatives reduces the influence of lignin sources and extraction methods on electrochemical performance, it has problems such as low yield, high energy consumption, and insufficient utilization of abundant oxygen-containing functional groups. On the third hand, the photoanode, counter electrode and electrolyte materials used in DSSCs are mostly nanomaterials. The distance between nanoparticles is extremely short, and the van der Waals force between particles is much greater than their own gravity, so they tend to attract each other and agglomerate to form nanoaggregates, resulting in reduced conductivity and electrocatalytic performance of DSSCs. Summary of the invention

[0004] In view of the above problems and in order to better exert the performance of the photoanode, the counter electrode and the electrolyte, the present invention uses lignin derivatives to modify the photoanode, the counter electrode and the electrolyte, and assembles them to form a solar cell. Lignin derivatives as surfactants can reduce the generation of nano-aggregates; at the same time, using lignin derivatives as additives can better exert their own advantages such as redox properties and pseudocapacitance; in addition, lignin derivatives have the function of regulating microstructure, can increase the specific surface area of ​​the photoanode and the counter electrode, and improve the photoelectric conversion efficiency of DSSCs.

[0005] To achieve the purpose and other advantages of the present invention, the present invention provides a method for preparing an alkali lignin (AL) modified titanium dioxide (P25) photoanode, comprising:

[0006] S1, alkali lignin (AL) is dissolved in ethanol, and a lignin / ethanol mixed solution is obtained after ultrasonic stirring, and the supernatant is collected after centrifugation to obtain a lignin / ethanol solution;

[0007] S2, nano-titanium dioxide (P25), ethyl cellulose, and α-pineneol were dissolved in the lignin / ethanol solution prepared in S1, and the photoanode material was obtained after ultrasonic stirring for 12 hours, recorded as AL / P25 slurry, and the mass ratio of alkali lignin (AL) to ethyl cellulose and titanium dioxide (P25) was 1:200:400.

[0008] Specifically, alkali lignin (AL) has multiple sources, namely wheat straw (AL1), mixed coniferous forest and broadleaved forest (AL2), American pine (AL3), and wheat straw (AL1) is preferred.

[0009] Specifically, the titanium dioxide (P25) used is anatase titanium dioxide (P25) having a particle size of 25 nanometers.

[0010] Preferably, 3 mg of alkali lignin (AL1) is added to every 12 ml of ethanol solution, and the mass ratio of ethyl cellulose to titanium dioxide (P25) is 1:2, and it is named as photoanode AL1-3. (Example 6)

[0011] Preferably, 4 mg of alkali lignin (AL1) is added to every 12 ml of ethanol solution, and the mass ratio of ethyl cellulose to titanium dioxide (P25) is 1:2, and it is named as photoanode AL1-4. (Example 8)

[0012] The present invention provides a method for preparing a sodium lignin sulfonate (SL) modified PEDOT counter electrode, comprising:

[0013] S1. EDOT (3,4-ethylenedioxythiophene) was dissolved in deionized water and ultrasonically stirred to obtain an EDOT aqueous solution. 50 ml of deionized water was required for every 0.1 M EDOT.

[0014] S2, sodium lignin sulfonate was dissolved in the EDOT aqueous solution, and ultrasonic stirring was performed for 30 min to obtain the SL / EDOT aqueous solution as the electrodeposition solution;

[0015] S3. Use SL / EDOT as the electrodeposition solution, Pt as the counter electrode, FTO conductive substrate as the working electrode, Ag / AgCl as the reference electrode, and prepare the SL / PEDOT counter electrode by constant current electrodeposition at a current of 3.4 mA.

[0016] Preferably, the sodium lignin sulfonate in S2 is derived from a mixture of coniferous forests and broad-leaved forests.

[0017] Preferably, the mass ratio of EDOT to sodium lignin sulfonate is 1:1.5, and the constant current electrodeposition lasts for 30 seconds, which is named as the counter electrode SL1.5-30s. (Example 1)

[0018] Preferably, the mass ratio of EDOT to sodium lignin sulfonate is 1:1.5, and the constant current electrodeposition lasts for 15 seconds, which is named as the counter electrode SL1.5-15s. (Example 2)

[0019] Preferably, the mass ratio of EDOT to sodium lignin sulfonate is 1:2, and the constant current electrodeposition lasts for 30 seconds, which is named as the counter electrode SL2-30s. (Example 5)

[0020] The present invention provides a method for preparing a lignin derivative modified iodine electrolyte, comprising:

[0021] S1, dissolving the lignin derivative in acetonitrile, taking the supernatant after ultrasonic centrifugation to obtain a lignin derivative / acetonitrile solution;

[0022] S2, valeronitrile, 1-methyl-3-propylimidazolium iodide (PMII), guanidine cyanide sulfate, iodine (I2), and 4-tert-butylpyridine were dissolved in the lignin / acetonitrile solution prepared in S1, and an AL electrolyte was obtained after ultrasonic stirring for 30 minutes, recorded as AL / I electrolyte, wherein the volume ratio of acetonitrile to valeronitrile was 85:15wt%, and the mass ratio of iodine, guanidine cyanide sulfate, 4-tert-butylpyridine, and 1-methyl-3-propylimidazolium iodide was 42:80:450:1000.

[0023] Specifically, the lignin derivatives in S1 include: alkali lignin (AL), sodium lignin sulfonate (SL), and dealkalized lignin (DL), all of which are derived from American pine. Preferably, it is alkali lignin (AL).

[0024] Preferably, 3 mg AL is added to every 10 ml acetonitrile, and the electrolyte is named AL-3. (Example 11)

[0025] Preferably, 2 mg AL is added to every 10 ml acetonitrile, and the electrolyte is named AL-2. (Example 12)

[0026] Preferably, 4 mg AL is added to every 10 ml acetonitrile, and the electrolyte is named AL-4. (Example 13)

[0027] The present invention provides a dye-sensitized solar cell, comprising: an alkali lignin (AL) modified titanium dioxide (P25) photoanode or a sodium lignin sulfonate (SL) modified PEDOT counter electrode or a lignin derivative modified iodine electrolyte prepared by the above preparation method, assembled by any one or more thereof.

[0028] The present invention provides a dye-sensitized solar cell, comprising: a conductive substrate, a photoanode, a dye sensitizer, an electrolyte, and a counter electrode; wherein the photoanode, the counter electrode, and the electrolyte are any combination of the following:

[0029] A: unmodified titanium dioxide photoanode, counter electrode SL1.5-30s, unmodified iodine electrolyte; (Example 1) or

[0030] B: unmodified titanium dioxide photoanode, counter electrode SL1.5-15s, unmodified iodine electrolyte; (Example 2) or

[0031] C: unmodified titanium dioxide photoanode, counter electrode SL2-30s, unmodified iodine electrolyte; (Example 5) or

[0032] D: photoanode AL1-3, unmodified Pt counter electrode, unmodified iodine electrolyte; (Example 6) or

[0033] E: photoanode AL1-4, unmodified Pt counter electrode, unmodified iodine electrolyte; (Example 8) or

[0034] F: unmodified titanium dioxide photoanode, unmodified Pt counter electrode, AL-3 electrolyte; (Example 11) or

[0035] G: unmodified titanium dioxide photoanode, unmodified Pt counter electrode, AL-2 electrolyte; (Example 12) or

[0036] H: unmodified titanium dioxide photoanode, unmodified Pt counter electrode, AL-4 electrolyte; (Example 13) or.

[0037] I: Photoanode AL1-3, unmodified Pt counter electrode, AL-3 electrolyte.

[0038] The present invention has at least the following beneficial effects:

[0039] 1. The present invention uses lignin derivatives with stable chemical structure and redox properties as additives, and adds them to the photoanode, counter electrode and electrolyte of DSSCs in a simple way for modification. While making full use of the advantages of lignin derivatives such as rich oxygen-containing functional groups and good redox properties, lignin derivatives are used to regulate the molecular forces inside the photoanode, counter electrode and electrolyte to form a directional arrangement structure with low agglomeration and high specific surface area that is more conducive to the photoelectric conversion process of DSSCs. Among them, lignin derivatives not only play a role in reducing agglomeration, but also guide the internal titanium dioxide (TiO2) crystals, PEDOT crystals and I by establishing interaction forces with crystals or ions. - The ions are more conducive to photoelectric conversion. The present invention expands the application field of biomass materials and provides an effective application for the development of lignin derivatives in the field of solar cells.

[0040] 2. The lignin derivatives of the present invention, as biomass supramolecules, themselves have many oxygen-containing functional groups, such as phenolic hydroxyl groups. The oxygen-containing functional groups of alkali lignin (AL) often act as active sites in catalysts, improving the redox ability of photoanode, counter electrode and electrolyte. Research on alkali lignin (AL) as template for modified TiO2 nanoparticles Alkali lignin (AL) as a template for nanomaterials can optimize the inherent structure of TiO2. Alkali lignin (AL) can reduce the interaction force between TiO2 crystals and reduce the agglomeration of TiO2. SL, as an organic additive, has a certain level of surface activity, can control the formation and growth of crystal nuclei, and at the same time increase the overpotential of PEDOT to form a PEDOT deposition layer with small size, high specific surface area and low trap density. SL itself can enhance redox properties and pseudocapacitance, and can increase the conductivity and electrocatalytic activity of PEDOT electrodes without changing the crystal structure of PEDOT. As an additive, alkali lignin (AL) can provide bulky cations for the electrolyte, adsorb I- and I3- in the electrolyte near the photoanode, and enhance the electron transfer power and the open circuit voltage (V) of dye-sensitized solar cells. OC ). The present invention further selects a suitable combination of photoanode, counter electrode and electrolyte to give full play to the performance of dye-sensitized solar cells and improve the photoelectric conversion efficiency.

[0041] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 The photoanode preparation process flow chart of the present invention;

[0043] Figure 2 This is a flow chart for preparing the SL / PEDOT electrode of the present invention;

[0044] Figure 3 is the JV curve of Example 1 of the present invention;

[0045] Figure 4 is the JV curve of Example 2 of the present invention;

[0046] Figure 5 is the JV curve of Example 3 of the present invention;

[0047] Figure 6 is the JV curve of Example 4 of the present invention;

[0048] Figure 7 is the JV curve of Example 5 of the present invention;

[0049] Figure 8 is the JV curve of Example 6 of the present invention;

[0050] Fig. 9 is the JV curve of Example 7 of the present invention;

[0051] Fig.10 is the JV curve of Example 8 of the present invention;

[0052] Fig.11 is the JV curve of Example 9 of the present invention;

[0053] Fig.12 is the JV curve of Example 10 of the present invention;

[0054] Fig.13 is the JV curve of Example 11 of the present invention;

[0055] Fig.14 is the JV curve of Example 12 of the present invention;

[0056] Fig.15 is the JV curve of Example 13 of the present invention;

[0057] Fig.16 is the JV curve of Example 14 of the present invention;

[0058] Fig.17 is the JV curve of Example 15 of the present invention;

[0059] Fig.18 is the JV curve of Example 16 of the present invention;

[0060] Fig.19 is the JV curve of Example 17 of the present invention;

[0061] Fig. 20 is the JV curve of Example 18 of the present invention;

[0062] Fig.21 is the JV curve of Example 19 of the present invention;

[0063] Fig. 22 It is the JV curve of comparative example 1 of the present invention;

[0064] Fig.23 1 and 2 are JV curves of Example 6, Example 9 and Example 10 of the present invention under dark conditions. DETAILED DESCRIPTION

[0065] The present invention is further described in detail below in conjunction with embodiments so that those skilled in the art can implement the invention with reference to the description.

[0066] In the present invention:

[0067] P25 is anatase titanium dioxide with a particle size of 25 nanometers.

[0068] EDOT is 3,4-ethylenedioxythiophene.

[0069] Dealkalized lignin is DL.

[0070] Alkali lignin is AL; among them, wheat straw is AL1, mixed coniferous and broad-leaved forests are AL2, and American pine is AL3.

[0071] Sodium lignin sulfonate is SL.

[0072] 1-Methyl-3-propylimidazolium iodide is PMII.

[0073] Iodine is I2.

[0074] The photoanode preparation process is as follows: Figure 1 The preparation process of the electrode is as shown in Figure 2 shown.

[0075] Example 1 (Assembly of unmodified P25 photoanode + modified counter electrode SL1.5-30s + unmodified iodine electrolyte into DSSCs)

[0076] In this embodiment, a dye-sensitized solar cell comprising a photoanode, a counter electrode and an electrolyte is prepared and assembled.

[0077] 1. Photoanode preparation:

[0078] Apply P25 slurry on the FTO conductive glass with 3M tape to an area of ​​0.25 cm 2 square; put it into a tube furnace and sinter it at 450℃ for 30min in air atmosphere to obtain a pretreated P25 photoanode; immerse it in a TiCl4 aqueous solution with a concentration of 40mmol / L, soak it at 70℃ for 30min, then take it out and clean the surface with anhydrous ethanol, blow it dry and put it into a tube sintering furnace for annealing at 450℃ for 30min; when the temperature drops to 70℃, quickly put it into N719 dye, stand it in the dark for 22h, and then clean the unadsorbed dye on the surface with deionized water and anhydrous ethanol in turn to obtain a P25 photoanode;

[0079] 2. Preparation of sodium lignin sulfonate (SL) modified PEDOT counter electrode:

[0080] S1. EDOT was dissolved in deionized water, and EDOT aqueous solution was obtained after ultrasonic stirring. 50 ml of deionized water was required for every 0.1 M EDOT.

[0081] S2. Sodium lignin sulfonate was dissolved in an EDOT aqueous solution, and ultrasonic stirring was performed for 30 minutes to obtain an SL / EDOT aqueous solution as an electrodeposition solution, wherein the mass ratio of EDOT to sodium lignin sulfonate was 1:1.5.

[0082] S3. Use SL / EDOT as the electrodeposition solution, Pt as the counter electrode, FTO conductive substrate as the working electrode, Ag / AgCl as the reference electrode, and prepare the SL / PEDOT counter electrode by constant current electrodeposition at a current of 3.4 mA for 30 s, named SL1.5-30s.

[0083] 3. Electrolyte: comprising 0.025M I2, 0.6M PMII, 0.1M guanidine thiocyanate, 0.5M 4-tert-butylpyridine, and the solvent is acetonitrile and valeronitrile (volume ratio is 85:15wt%); ultrasonication for 30 minutes to obtain unmodified iodine electrolyte.

[0084] 4. N719 dye as dye sensitizer: weigh 29.7 mg of N719 dye and dissolve it in 50 ml of anhydrous ethanol, sonicate for 30 min, and store in dark place.

[0085] 5. Battery assembly: A 60μm thick film is placed between the counter electrode and the dye-sensitized photoanode, then heat-sealed at 120°C. After cooling to room temperature, electrolyte is dripped on the hole on the back of the counter electrode; vacuum filtration is performed to allow all the electrolyte on the hole to enter the battery. The battery packaging is completed to obtain a dye-sensitized solar cell.

[0086] DSSCs were assembled using the P25 photoanode, SL1.5-30s counter electrode and iodine electrolyte obtained above.

[0087] Example 2 (Assembly of unmodified P25 photoanode + modified counter electrode SL1.5-15s + unmodified iodine electrolyte into DSSCs)

[0088] In this embodiment, the preparation of the electrode is as follows:

[0089] 1. Preparation of sodium lignin sulfonate modified PEDOT counter electrode:

[0090] S1. EDOT was dissolved in deionized water, and EDOT aqueous solution was obtained after ultrasonic stirring. 50 ml of deionized water was required for every 0.1 M EDOT.

[0091] S2. Sodium lignin sulfonate was dissolved in an EDOT aqueous solution, and ultrasonic stirring was performed for 30 minutes to obtain an SL / EDOT aqueous solution as an electrodeposition solution, wherein the mass ratio of EDOT to sodium lignin sulfonate was 1:1.5.

[0092] S3. Use SL / EDOT as the electrodeposition solution, Pt as the counter electrode, FTO conductive substrate as the working electrode, Ag / AgCl as the reference electrode, and prepare the SL / PEDOT counter electrode by constant current electrodeposition at a current of 3.4 mA for 15 s, named SL1.5-15s.

[0093] The SL1.5-15s obtained above was used as the counter electrode, and the other conditions were the same as in Example 1 to assemble DSSCs. Example 3 (Assembly of unmodified P25 photoanode + modified counter electrode SL1.5-45s + unmodified iodine electrolyte into DSSCs)

[0094] In this embodiment, the preparation of the electrode is as follows:

[0095] 1. Preparation of sodium lignin sulfonate modified PEDOT counter electrode:

[0096] S1. EDOT was dissolved in deionized water, and EDOT aqueous solution was obtained after ultrasonic stirring. 50 ml of deionized water was required for every 0.1 M EDOT.

[0097] S2. Sodium lignin sulfonate was dissolved in an EDOT aqueous solution, and ultrasonic stirring was performed for 30 minutes to obtain an SL / EDOT aqueous solution as an electrodeposition solution, wherein the mass ratio of EDOT to sodium lignin sulfonate was 1:1.5.

[0098] S3. Use SL / EDOT as the electrodeposition solution, Pt as the counter electrode, FTO conductive substrate as the working electrode, Ag / AgCl as the reference electrode, and prepare the SL / PEDOT counter electrode by constant current electrodeposition at a current of 3.4 mA for 45 seconds, named SL1.5-45s.

[0099] The SL1.5-45s obtained above was used as the counter electrode, and the other conditions were the same as those in Example 1 to assemble DSSCs. Example 4 (Assembly of unmodified P25 photoanode + modified counter electrode SL1-30s + unmodified iodine electrolyte into DSSCs)

[0100] In this embodiment, the preparation of the electrode is as follows:

[0101] 1. Preparation of sodium lignin sulfonate modified PEDOT counter electrode:

[0102] S1. EDOT was dissolved in deionized water, and EDOT aqueous solution was obtained after ultrasonic stirring. 50 ml of deionized water was required for every 0.1 M EDOT.

[0103] S2. Sodium lignin sulfonate was dissolved in an EDOT aqueous solution, and ultrasonic stirring was performed for 30 minutes to obtain an SL / EDOT aqueous solution as an electrodeposition solution, wherein the mass ratio of EDOT to sodium lignin sulfonate was 1:1.

[0104] S3. Use SL / EDOT as the electrodeposition solution, Pt as the counter electrode, FTO conductive substrate as the working electrode, Ag / AgCl as the reference electrode, and prepare the SL / PEDOT counter electrode by constant current electrodeposition at a current of 3.4 mA for 30 seconds, named SL1-30s.

[0105] The SL1-30s obtained above was used as the counter electrode, and the other conditions were the same as in Example 1 to assemble DSSCs. Example 5 (Assembly of unmodified P25 photoanode + modified counter electrode SL2-30s + unmodified iodine electrolyte into DSSCs)

[0106] In this embodiment, the preparation of the electrode is as follows:

[0107] 1. Preparation of sodium lignin sulfonate modified PEDOT counter electrode:

[0108] S1. EDOT was dissolved in deionized water, and EDOT aqueous solution was obtained after ultrasonic stirring. 50 ml of deionized water was required for every 0.1 M EDOT.

[0109] S2. Sodium lignin sulfonate was dissolved in an EDOT aqueous solution, and ultrasonic stirring was performed for 30 minutes to obtain an SL / EDOT aqueous solution as an electrodeposition solution, wherein the mass ratio of EDOT to sodium lignin sulfonate was 1:2.

[0110] S3. Use SL / EDOT as the electrodeposition solution, Pt as the counter electrode, FTO conductive substrate as the working electrode, Ag / AgCl as the reference electrode, and prepare the SL / PEDOT counter electrode by constant current electrodeposition at a current of 3.4 mA for 30 seconds, named SL2-30s.

[0111] The SL2-30s obtained above was used as the counter electrode, and the other steps were the same as in Example 1 to assemble DSSCs. Example 6 (Modified P25 photoanode AL1-3 + unmodified Pt counter electrode + unmodified iodine electrolyte to assemble DSSCs)

[0112] In this embodiment, a dye-sensitized solar cell comprising a photoanode, a counter electrode and an electrolyte is prepared and assembled.

[0113] 1. Preparation of Alkali Lignin (AL) Modified P25 Photoanode:

[0114] S1. Take AL1 made of wheat straw and dissolve it in ethanol. After ultrasonic stirring, obtain an alkali lignin (AL) / ethanol mixed solution. After centrifugation, take the supernatant to obtain an alkali lignin (AL) / ethanol solution; add 3 mg of alkali lignin (AL) to every 12 ml of ethanol solution.

[0115] S2, 25 nanometer titanium dioxide (P25), ethyl cellulose, and α-pineneol were dissolved in a lignin / ethanol solution, and ultrasonic stirring was performed for 12 hours to obtain an AL / P25 slurry as a photoanode material. The mass ratio of the ethyl cellulose to titanium dioxide (P25) was 1:2, and the slurry was named AL1-3.

[0116] 2. Counter electrode preparation: Chloroplatinic acid, OP emulsifier and pentanediol solution are mixed to obtain a platinum solution; the mass ratio of chloroplatinic acid to OP emulsifier is 1.295:1. Take a drop of the platinum solution and add it to the FTO conductive glass with 3M tape, with an area slightly larger than 0.25cm 2 In the square; after the platinum solution evaporates, a drop is added to the surface of the FTO conductive glass for the second time. After evaporation again, it is placed in a tube furnace and sintered at 450°C for 30 minutes in an air atmosphere to obtain a Pt counter electrode.

[0117] 3. Electrolyte: comprising 0.025M I2, 0.6M PMII, 0.1M guanidine thiocyanate, 0.5M 4-tert-butylpyridine, and the solvent is acetonitrile and valeronitrile (volume ratio is 85:15wt%); ultrasonication for 30 minutes to obtain iodine electrolyte.

[0118] 4. N719 dye: Weigh 29.7 mg of N719 dye and dissolve it in 50 ml of anhydrous ethanol. Ultrasonicate for 30 min and store in a dark place.

[0119] 5. Battery assembly: A 60μm thick film is placed between the counter electrode and the dye-sensitized photoanode, then heat-sealed at 120°C. After cooling to room temperature, electrolyte is dripped on the hole on the back of the counter electrode; vacuum filtration is performed to allow all the electrolyte on the hole to enter the battery. The battery packaging is completed to obtain a dye-sensitized solar cell.

[0120] DSSCs were assembled using the AL1-3 photoanode, Pt counter electrode and iodine electrolyte obtained above.

[0121] Example 7 (Modified P25 photoanode AL1-2 + unmodified Pt counter electrode + unmodified iodine electrolyte assembled into DSSCs)

[0122] In this embodiment, the photoanode, the counter electrode and the electrolyte are prepared as follows:

[0123] 1. Preparation of alkali lignin modified P25 photoanode:

[0124] S1. Take AL1 made of wheat straw and dissolve it in ethanol. After ultrasonic stirring, obtain an alkali lignin / ethanol mixed solution. After centrifugation, take the supernatant to obtain an alkali lignin / ethanol solution. Add 2 mg of alkali lignin to every 12 ml of ethanol solution.

[0125] S2, 25 nanometer titanium dioxide (P25), ethyl cellulose, and α-pineneol were dissolved in a lignin / ethanol solution, and ultrasonic stirring was performed for 12 hours to obtain an AL / P25 slurry as a photoanode material. The mass ratio of the ethyl cellulose to titanium dioxide (P25) was 1:2, and the slurry was named AL1-2.

[0126] DSSCs were assembled using the AL1-2 photoanode obtained above, the Pt counter electrode and the iodine electrolyte in Example 6. Example 8 (Modified P25 photoanode AL1-4 + unmodified Pt counter electrode + unmodified iodine electrolyte assembled into DSSCs)

[0127] In this embodiment, the photoanode, the counter electrode and the electrolyte are prepared as follows:

[0128] 1. Preparation of alkali lignin modified P25 photoanode:

[0129] S1. Take AL1 made of wheat straw and dissolve it in ethanol. After ultrasonic stirring, obtain an alkali lignin (AL) / ethanol mixed solution. After centrifugation, take the supernatant to obtain an alkali lignin (AL) / ethanol solution. Add 4 mg of alkali lignin (AL) to every 12 ml of ethanol solution.

[0130] S2, 25 nanometer titanium dioxide (P25), ethyl cellulose, and α-pineneol were dissolved in a lignin / ethanol solution, and ultrasonic stirring was performed for 12 hours to obtain an AL / P25 slurry as a photoanode material. The mass ratio of the ethyl cellulose to titanium dioxide (P25) was 1:2, and the slurry was named AL1-4.

[0131] DSSCs were assembled using the AL1-4 photoanode obtained above, the Pt counter electrode and the iodine electrolyte in Example 6. Example 9 (Modified P25 photoanode AL2-3 + unmodified Pt counter electrode + unmodified iodine electrolyte assembled into DSSCs)

[0132] In this embodiment, the photoanode, the counter electrode and the electrolyte are prepared as follows:

[0133] 1. Preparation of Alkali Lignin (AL) Modified P25 Photoanode:

[0134] S1. Take AL2, a mixture of coniferous forest and broad-leaved forest, and dissolve it in ethanol. After ultrasonic stirring, obtain an alkali lignin (AL) / ethanol mixed solution. After centrifugation, take the supernatant to obtain an alkali lignin (AL) / ethanol solution, and add 3 mg of alkali lignin (AL) to every 12 ml of ethanol solution.

[0135] S2, 25 nanometer titanium dioxide (P25), ethyl cellulose, and α-pineneol were dissolved in a lignin / ethanol solution, and ultrasonic stirring was performed for 12 hours to obtain an AL / P25 slurry as a photoanode material. The mass ratio of the ethyl cellulose to titanium dioxide (P25) was 1:2, and the slurry was named AL2-3.

[0136] DSSCs were assembled using the AL2-3 photoanode obtained above, the Pt counter electrode and the iodine electrolyte in Example 6. Example 10 (Modified P25 photoanode AL3-3 + unmodified Pt counter electrode + unmodified iodine electrolyte assembled into DSSCs)

[0137] In this embodiment, the photoanode, the counter electrode and the electrolyte are prepared as follows:

[0138] 1. Preparation of Alkali Lignin (AL) Modified P25 Photoanode:

[0139] S1. Take AL3 made of American pine and dissolve it in ethanol. After ultrasonic stirring, obtain an alkali lignin (AL) / ethanol mixed solution. After centrifugation, take the supernatant to obtain an alkali lignin (AL) / ethanol solution. Add 3 mg of alkali lignin (AL) to every 12 ml of ethanol solution.

[0140] S2, 25 nanometer titanium dioxide (P25), ethyl cellulose, and α-pineneol were dissolved in a lignin / ethanol solution, and ultrasonic stirring was performed for 12 hours to obtain an AL / P25 slurry as a photoanode material. The mass ratio of the ethyl cellulose to titanium dioxide (P25) was 1:2, and it was named AL3-3.

[0141] DSSCs were assembled using the AL3-3 photoanode obtained above, the Pt counter electrode and the iodine electrolyte in Example 6. Example 11 (Assembly of unmodified P25 photoanode + unmodified Pt counter electrode + modified iodine electrolyte AL-3 into DSSCs)

[0142] In this example, the photoanode, counter electrode and electrolyte were prepared as follows:

[0143] 1. Photoanode preparation:

[0144] Take P25 slurry and apply it on the FTO conductive glass with 3M tape, with an area of ​​0.25cm 2 square; put it into a tube furnace and sinter it at 450℃ for 30min in air atmosphere to obtain P25 photoanode; immerse it in a TiCl4 aqueous solution with a concentration of 40mmol / L, soak it at 70℃ for 30min, then take it out and clean the surface with anhydrous ethanol, blow it dry and put it into a tube sintering furnace for annealing at 450℃ for 30min; when the temperature drops to 70℃, quickly put it into N719 dye, stand it in the dark for 22h, and then clean the unadsorbed dye on the surface with deionized water and anhydrous ethanol in turn to obtain P25 photoanode;

[0145] 2. Counter electrode preparation: Chloroplatinic acid, OP emulsifier and pentanediol solution are mixed to obtain a platinum solution; the mass ratio of chloroplatinic acid to OP emulsifier is 1.295:1. Take a drop of the platinum solution and add it to the FTO conductive glass with 3M tape, with an area slightly larger than 0.25cm 2 In the square; after the platinum solution evaporates, a drop is added to the surface of the FTO conductive glass for the second time. After evaporation again, it is placed in a tube furnace and sintered at 450°C for 30 minutes in an air atmosphere to obtain a Pt counter electrode.

[0146] 3. Preparation of AL modified iodine electrolyte:

[0147] S1 and AL were dissolved in acetonitrile, and an alkali lignin (AL) / acetonitrile mixed solution was obtained after ultrasonic stirring. The supernatant was taken after centrifugation to obtain an AL / acetonitrile solution.

[0148] S2, valeronitrile, iodine, guanidine cyanide sulfate, 4-tert-butylpyridine, and 1-methyl-3-propyl imidazolium iodide were dissolved in an alkali lignin (AL) / acetonitrile solution and ultrasonicated for 30 minutes to obtain an electrolyte in which the mass ratio of iodine, guanidine cyanide sulfate, 4-tert-butylpyridine, and 1-methyl-3-propyl imidazolium iodide was 42:80:450:1000, the volume ratio of acetonitrile to valeronitrile was 85:15wt%, and 3 mg AL was added to every 10 ml acetonitrile. The electrolyte was named AL-3.

[0149] 4. N719 dye: Weigh 29.7 mg of N719 dye and dissolve it in 50 ml of anhydrous ethanol. Ultrasonicate for 30 min and store in a dark place.

[0150] 5. Battery assembly: A 60μm thick film is placed between the counter electrode and the dye-sensitized photoanode, then heat-sealed at 120°C. After cooling to room temperature, electrolyte is dripped on the hole on the back of the counter electrode; vacuum filtration is performed to allow all the electrolyte on the hole to enter the battery. The battery packaging is completed to obtain a dye-sensitized solar cell.

[0151] DSSCs were assembled using P25 photoanode and Pt counter electrode with AL-3 electrolyte.

[0152] Example 12 (Assembly of unmodified P25 photoanode + unmodified Pt counter electrode + modified iodine electrolyte AL-2 into DSSCs)

[0153] In this embodiment, AL modified iodine electrolyte is prepared:

[0154] S1 and AL were dissolved in acetonitrile, and an alkali lignin (AL) / acetonitrile mixed solution was obtained after ultrasonic stirring. The supernatant was taken after centrifugation to obtain an AL / acetonitrile solution.

[0155] S2, valeronitrile, iodine, guanidine cyanide sulfate, 4-tert-butylpyridine, and 1-methyl-3-propyl imidazolium iodide were dissolved in an alkali lignin (AL) / acetonitrile solution and ultrasonicated for 30 minutes to obtain an electrolyte in which the mass ratio of iodine, guanidine cyanide sulfate, 4-tert-butylpyridine, and 1-methyl-3-propyl imidazolium iodide was 42:80:450:1000, the volume ratio of acetonitrile to valeronitrile was 85:15wt%, and 2 mg AL was added to every 10 ml acetonitrile. The electrolyte was named AL-2.

[0156] DSSCs were assembled using AL-2 electrolyte with the P25 photoanode and Pt counter electrode in Example 11.

[0157] Example 13 (Assembly of unmodified P25 photoanode + unmodified Pt counter electrode + modified iodine electrolyte AL-4 into DSSCs)

[0158] In this embodiment, the photoanode and the counter electrode are prepared as follows:

[0159] Preparation of AL modified iodine electrolyte:

[0160] S1 and AL were dissolved in acetonitrile, and an alkali lignin (AL) / acetonitrile mixed solution was obtained after ultrasonic stirring. The supernatant was taken after centrifugation to obtain an AL / acetonitrile solution.

[0161] S2, valeronitrile, iodine, guanidine cyanide sulfate, 4-tert-butylpyridine, and 1-methyl-3-propyl imidazolium iodide were dissolved in an alkali lignin (AL) / acetonitrile solution and ultrasonicated for 30 minutes to obtain an electrolyte in which the mass ratio of iodine, guanidine cyanide sulfate, 4-tert-butylpyridine, and 1-methyl-3-propyl imidazolium iodide was 42:80:450:1000, the volume ratio of acetonitrile to valeronitrile was 85:15wt%, and 4 mg AL was added per 10 ml acetonitrile. The electrolyte was named AL-4.

[0162] DSSCs were assembled using AL-4 electrolyte with the P25 photoanode and Pt counter electrode in Example 11.

[0163] Example 14 (Assembly of unmodified P25 photoanode + unmodified Pt counter electrode + modified iodine electrolyte DL-3 into DSSCs)

[0164] In this embodiment, the electrolyte is prepared as follows:

[0165] Preparation of DL modified iodine electrolyte:

[0166] S1. The dealkalized lignin DL is dissolved in acetonitrile, and a dealkalized lignin (DL) / acetonitrile mixed solution is obtained after ultrasonic stirring. The supernatant is collected after centrifugation to obtain a DL / acetonitrile solution.

[0167] S2, valeronitrile, iodine, guanidine cyanide sulfate, 4-tert-butylpyridine, and 1-methyl-3-propyl imidazolium iodide were dissolved in dealkalized lignin (DL) / acetonitrile solution and ultrasonicated for 30 minutes to obtain an electrolyte in which the mass ratio of iodine, guanidine cyanide sulfate, 4-tert-butylpyridine, and 1-methyl-3-propyl imidazolium iodide was 42:80:450:1000, the volume ratio of acetonitrile to valeronitrile was 85:15wt%, and 3 mg DL was added to every 10 ml acetonitrile. The electrolyte was named DL-3.

[0168] DSSCs were assembled using DL-3 electrolyte with the P25 photoanode and Pt counter electrode in Example 11.

[0169] Example 15 (Assembly of unmodified P25 photoanode + unmodified Pt counter electrode + modified iodine electrolyte SL-3 into DSSCs)

[0170] In this embodiment, the electrolyte is prepared as follows:

[0171] Preparation of SL modified iodine electrolyte:

[0172] S1 and SL were dissolved in acetonitrile, and a sodium lignin sulfonate (SL) / acetonitrile mixed solution was obtained after ultrasonic stirring. The supernatant was collected after centrifugation to obtain a SL / acetonitrile solution.

[0173] S2, valeronitrile, iodine, guanidine cyanide sulfate, 4-tert-butylpyridine, and 1-methyl-3-propyl imidazolium iodide were dissolved in sodium lignin sulfonate (SL) / acetonitrile solution and ultrasonicated for 30 minutes to obtain an electrolyte in which the mass ratio of iodine, guanidine cyanide sulfate, 4-tert-butylpyridine, and 1-methyl-3-propyl imidazolium iodide was 42:80:450:1000, the volume ratio of acetonitrile to valeronitrile was 85:15wt%, and 3 mg SL was added to every 10 ml acetonitrile. The electrolyte was named SL-3.

[0174] DSSCs were assembled using SL-3 electrolyte with the P25 photoanode and Pt counter electrode in Example 11.

[0175] Example 16 (Assembly of unmodified P25 photoanode + modified counter electrode SL1.5-30s + modified iodine electrolyte AL-3 into DSSCs)

[0176] In this embodiment, the photoanode, the counter electrode and the electrolyte are prepared as follows:

[0177] 1. Photoanode preparation:

[0178] Take P25 slurry and apply it on the FTO conductive glass with 3M tape, with an area of ​​0.25cm 2square; put it into a tube furnace and sinter it at 450℃ for 30min in air atmosphere to obtain a pretreated P25 photoanode; immerse it in a TiCl4 aqueous solution with a concentration of 40mmol / L, soak it at 70℃ for 30min, then take it out and clean the surface with anhydrous ethanol, blow it dry and put it into a tube sintering furnace for annealing at 450℃ for 30min; when the temperature drops to 70℃, quickly put it into N719 dye, stand it in the dark for 22h, and then clean the unadsorbed dye on the surface with deionized water and anhydrous ethanol in turn to obtain a P25 photoanode;

[0179] 2. Preparation of sodium lignin sulfonate modified PEDOT counter electrode:

[0180] S1. EDOT was dissolved in deionized water, and EDOT aqueous solution was obtained after ultrasonic stirring. 50 ml of deionized water was required for every 0.1 M EDOT.

[0181] S2. Sodium lignin sulfonate was dissolved in an EDOT aqueous solution, and ultrasonic stirring was performed for 30 minutes to obtain an SL / EDOT aqueous solution as an electrodeposition solution, wherein the mass ratio of EDOT to sodium lignin sulfonate was 1:1.5.

[0182] S3. Use SL / EDOT as the electrodeposition solution, Pt as the counter electrode, FTO conductive substrate as the working electrode, Ag / AgCl as the reference electrode, and prepare the SL / PEDOT counter electrode by constant current electrodeposition at a current of 3.4 mA for 30 seconds, named SL1.5-30s.

[0183] 3. Preparation of AL modified iodine electrolyte:

[0184] S1 and AL were dissolved in acetonitrile, and an alkali lignin (AL) / acetonitrile mixed solution was obtained after ultrasonic stirring. The supernatant was taken after centrifugation to obtain an AL / acetonitrile solution.

[0185] S2, valeronitrile, iodine, guanidine cyanide sulfate, 4-tert-butylpyridine, and 1-methyl-3-propyl imidazolium iodide were dissolved in an alkali lignin (AL) / acetonitrile solution and ultrasonicated for 30 minutes to obtain an electrolyte in which the mass ratio of iodine, guanidine cyanide sulfate, 4-tert-butylpyridine, and 1-methyl-3-propyl imidazolium iodide was 42:80:450:1000, the volume ratio of acetonitrile to valeronitrile was 85:15wt%, and 3 mg AL was added to every 10 ml acetonitrile. The electrolyte was named AL-3.

[0186] DSSCs were assembled using the P25 photoanode, SL1.5-30s counter electrode and AL-3 electrolyte obtained above, and the rest was the same as in Example 1.

[0187] Example 17 (Modified photoanode AL1-3 + unmodified Pt counter electrode + modified iodine electrolyte AL-3 assembled into DSSCs)

[0188] In this embodiment, the photoanode, the counter electrode and the electrolyte are prepared as follows:

[0189] 1. Preparation of Alkali Lignin (AL) Modified P25 Photoanode:

[0190] S1. Take AL1 made of wheat straw and dissolve it in ethanol. After ultrasonic stirring, obtain an alkali lignin (AL) / ethanol mixed solution. After centrifugation, take the supernatant to obtain an alkali lignin (AL) / ethanol solution. Add 4 mg of alkali lignin (AL) to every 12 ml of ethanol solution.

[0191] S2, 25 nanometer titanium dioxide (P25), ethyl cellulose, and α-pineneol were dissolved in a lignin / ethanol solution, and ultrasonic stirring was performed for 12 hours to obtain an AL / P25 slurry as a photoanode material. The mass ratio of the ethyl cellulose to titanium dioxide (P25) was 1:2, and the slurry was named AL1-3.

[0192] 2. Counter electrode preparation: Chloroplatinic acid, OP emulsifier and pentanediol solution are mixed to obtain a platinum solution; the mass ratio of chloroplatinic acid to OP emulsifier is 1.295:1. Take a drop of the platinum solution and add it to the FTO conductive glass with 3M tape, with an area slightly larger than 0.25cm 2 In the square; after the platinum solution evaporates, a drop is added to the surface of the FTO conductive glass for the second time. After evaporation again, it is placed in a tube furnace and sintered at 450°C for 30 minutes in an air atmosphere to obtain a Pt counter electrode.

[0193] 3. Preparation of AL modified iodine electrolyte:

[0194] S1 and AL were dissolved in acetonitrile, and an alkali lignin (AL) / acetonitrile mixed solution was obtained after ultrasonic stirring. The supernatant was taken after centrifugation to obtain an AL / acetonitrile solution.

[0195] S2, valeronitrile, iodine, guanidine cyanide sulfate, 4-tert-butylpyridine, and 1-methyl-3-propyl imidazolium iodide were dissolved in an alkali lignin (AL) / acetonitrile solution and ultrasonicated for 30 minutes to obtain an electrolyte in which the mass ratio of iodine, guanidine cyanide sulfate, 4-tert-butylpyridine, and 1-methyl-3-propyl imidazolium iodide was 42:80:450:1000, the volume ratio of acetonitrile to valeronitrile was 85:15wt%, and 3 mg AL was added to every 10 ml acetonitrile. The electrolyte was named AL-3.

[0196] DSSCs were assembled using the AL1-3 photoanode, Pt counter electrode and AL-3 electrolyte obtained above, and the rest was the same as in Example 1.

[0197] Example 18 (Modified photoanode AL1-3 + modified counter electrode SL1.5-30s + unmodified iodine electrolyte assembled into DSSCs)

[0198] In this embodiment, the photoanode, the counter electrode and the electrolyte are prepared as follows:

[0199] 1. Preparation of Alkali Lignin (AL) Modified P25 Photoanode:

[0200] S1. Take AL1 made of wheat straw and dissolve it in ethanol. After ultrasonic stirring, obtain an alkali lignin (AL) / ethanol mixed solution. After centrifugation, take the supernatant to obtain an alkali lignin (AL) / ethanol solution. Add 4 mg of alkali lignin (AL) to every 12 ml of ethanol solution.

[0201] S2, 25 nanometer titanium dioxide (P25), ethyl cellulose, and α-pineneol were dissolved in a lignin / ethanol solution, and ultrasonic stirring was performed for 12 hours to obtain an AL / P25 slurry as a photoanode material. The mass ratio of the ethyl cellulose to titanium dioxide (P25) was 1:2, and the slurry was named AL1-3.

[0202] 2. Preparation of sodium lignin sulfonate modified PEDOT counter electrode:

[0203] S1. EDOT was dissolved in deionized water, and EDOT aqueous solution was obtained after ultrasonic stirring. 50 ml of deionized water was required for every 0.1 M EDOT.

[0204] S2. Sodium lignin sulfonate was dissolved in an EDOT aqueous solution, and ultrasonic stirring was performed for 30 minutes to obtain an SL / EDOT aqueous solution as an electrodeposition solution, wherein the mass ratio of EDOT to sodium lignin sulfonate was 1:1.5.

[0205] S3. Use SL / EDOT as the electrodeposition solution, Pt as the counter electrode, FTO conductive substrate as the working electrode, Ag / AgCl as the reference electrode, and prepare the SL / PEDOT counter electrode by constant current electrodeposition at a current of 3.4 mA for 30 seconds, named SL1.5-30s.

[0206] 3. Electrolyte: including 0.025M I2, 0.6M PMII, 0.1M guanidine thiocyanate, 0.5M 4-tert-butylpyridine, and the solvent is acetonitrile and valeronitrile (volume ratio is 85:15wt%).

[0207] DSSCs were assembled using the AL1-3 photoanode, SL1.5-30s counter electrode and I2 electrolyte obtained above, and the rest was the same as in Example 1.

[0208] Example 19 (Modified photoanode AL1-3 + modified counter electrode SL1.5-30s + modified iodine electrolyte AL-3 assembled into DSSCs)

[0209] In this embodiment, the photoanode, the counter electrode and the electrolyte are prepared as follows:

[0210] 1. Preparation of Alkali Lignin (AL) Modified P25 Photoanode:

[0211] S1. Take AL1 made of wheat straw and dissolve it in ethanol. After ultrasonic stirring, obtain an alkali lignin (AL) / ethanol mixed solution. After centrifugation, take the supernatant to obtain an alkali lignin (AL) / ethanol solution. Add 4 mg of alkali lignin (AL) to every 12 ml of ethanol solution.

[0212] S2, 25 nanometer titanium dioxide (P25), ethyl cellulose, and α-pineneol were dissolved in a lignin / ethanol solution, and ultrasonic stirring was performed for 12 hours to obtain an AL / P25 slurry as a photoanode material. The mass ratio of the ethyl cellulose to titanium dioxide (P25) was 1:2, and the slurry was named AL1-3.

[0213] 2. Preparation of sodium lignin sulfonate modified PEDOT counter electrode:

[0214] S1. EDOT was dissolved in deionized water, and EDOT aqueous solution was obtained after ultrasonic stirring. 50 ml of deionized water was required for every 0.1 M EDOT.

[0215] S2. Sodium lignin sulfonate was dissolved in an EDOT aqueous solution, and ultrasonic stirring was performed for 30 minutes to obtain an SL / EDOT aqueous solution as an electrodeposition solution, wherein the mass ratio of EDOT to sodium lignin sulfonate was 1:1.5.

[0216] S3. Use SL / EDOT as the electrodeposition solution, Pt as the counter electrode, FTO conductive substrate as the working electrode, Ag / AgCl as the reference electrode, and prepare the SL / PEDOT counter electrode by constant current electrodeposition at a current of 3.4 mA for 30 seconds, named SL1.5-30s.

[0217] 3. Preparation of AL modified iodine electrolyte:

[0218] S1 and AL were dissolved in acetonitrile, and an alkali lignin (AL) / acetonitrile mixed solution was obtained after ultrasonic stirring. The supernatant was taken after centrifugation to obtain an AL / acetonitrile solution.

[0219] S2, valeronitrile, iodine, guanidine cyanide sulfate, 4-tert-butylpyridine, and 1-methyl-3-propyl imidazolium iodide were dissolved in an alkali lignin (AL) / acetonitrile solution and ultrasonicated for 30 minutes to obtain an electrolyte in which the mass ratio of iodine, guanidine cyanide sulfate, 4-tert-butylpyridine, and 1-methyl-3-propyl imidazolium iodide was 42:80:450:1000, the volume ratio of acetonitrile to valeronitrile was 85:15wt%, and 3 mg AL was added to every 10 ml acetonitrile. The electrolyte was named AL-3.

[0220] DSSCs were assembled using the AL1-3 photoanode, SL1.5-30s counter electrode and AL-3 electrolyte obtained above, and the rest was the same as in Example 1.

[0221] Comparative Example 1 (Assembly of unmodified photoanode + unmodified Pt counter electrode + unmodified iodine electrolyte into DSSCs)

[0222] In this comparative example, the photoanode, counter electrode and electrolyte were prepared as follows:

[0223] 1. Photoanode preparation:

[0224] Take P25 slurry and apply it on the FTO conductive glass with 3M tape, with an area of ​​0.25cm 2 square; put it into a tube furnace and sinter it at 450℃ for 30min in air atmosphere to obtain P25 photoanode; immerse it in a TiCl4 aqueous solution with a concentration of 40mmol / L, soak it at 70℃ for 30min, then take it out and clean the surface with anhydrous ethanol, blow it dry and put it into a tube sintering furnace for annealing at 450℃ for 30min; when the temperature drops to 70℃, quickly put it into N719 dye, stand it in the dark for 22h, and then clean the unadsorbed dye on the surface with deionized water and anhydrous ethanol in turn to obtain P25 photoanode;

[0225] 2. Counter electrode preparation: Chloroplatinic acid, OP emulsifier and pentanediol solution are mixed to obtain a platinum solution; the mass ratio of chloroplatinic acid to OP emulsifier is 1.295:1. Take a drop of the platinum solution and add it to the FTO conductive glass with 3M tape, with an area slightly larger than 0.25cm 2 In the square; after the platinum solution evaporates, a drop is added to the surface of the FTO conductive glass for the second time. After evaporation again, it is placed in a tube furnace and sintered at 450°C for 30 minutes in an air atmosphere to obtain a Pt counter electrode.

[0226] 3. Electrolyte: comprising 0.025M I2, 0.6M PMII, 0.1M guanidine thiocyanate, 0.5M 4-tert-butylpyridine, and the solvent is acetonitrile and valeronitrile (volume ratio is 85:15wt%); ultrasonication for 30 minutes to obtain iodine electrolyte.

[0227] DSSCs were assembled using the P25 photoanode, Pt counter electrode and I2 electrolyte obtained above, and the rest was the same as in Example 1.

[0228] Effect Experiment

[0229] The photovoltaic performance of the dye-sensitized solar cells prepared in the above Examples 1-19 and Comparative Example 1 was tested, including the photoelectric conversion efficiency (PCE), short-circuit current (J SC ), open circuit voltage (V OC ), the specific results are shown in Table 1:

[0230] Table 1 Photovoltaic performance of dye-sensitized solar cells prepared in various embodiments and comparative examples

[0231]

[0232]

[0233] As can be seen from Table 1, the P25 photoanode, PEDOT counter electrode and I2 electrolyte were modified by using lignin derivatives as additives, and the AL / P25 and P25 photoanode, Pt and SL / PEDPT counter electrodes, I2 and AL / I electrolytes were arranged to assemble dye-sensitized solar cells, and the 100 mW / cm 2 The JV curve of the target DSSCs was tested under illumination, and the photovoltaic parameters obtained are shown in Table 1. Figures 3 to 22 shown.

[0234] By comparison, it was found that the SL / PEDOT counter electrode (Examples 1 to 5) was compared with the Pt counter electrode (Comparative Example 1). It was found that the P25|I2|SL / PEDOT assembled with the SL / PEDOT counter electrode (Examples 1 to 5) and the P25 photoanode and I2 electrolyte had a higher J SC and PCE, the improvement effect is very significant, but V OC As the SL content increases, J SC First, from the 19.19 mA / cm in Example 4 2 Increased to 29.03 mA / cm in Example 1 2 , and then decreased to 24.85 mA / cm in Example 5 2 ; PCE first increased from 7.14% in Example 4 to 9.49% in Example 1, and then decreased to 8.74% in Example 5. As the electrodeposition time increased, J SC First, from the 23.34 mA / cm in Example 2 2 Increased to 29.03 mA / cm in Example 1 2 , and then decreased to 21.22 mA / cm in Example 3 2 The PCE first increased from 7.83% in Example 2 to 9.49% in Example 1, and then decreased to 7.71% in Example 3. This can be attributed to the agglomeration of the PEODT film in SL1.5-45s in Example 3, which reduced the conductivity and catalytic activity, resulting in the decrease of J of P25|I2|SL1.5-45s in Example 3. SC and PCE reduction.

[0235] AL1-3|I2|Pt of Example 6 at 100mW / cm 2Under illumination, a PCE of 8.83% was obtained, and V OC 0.69V, J SC 25.635mA / cm 2 Compared with P25|I2|Pt of Comparative Example 1, J SC Compared with P25|I2|Pt in Comparative Example 1, the V OC The increase in the value can be attributed to the fact that the addition of AL provides more cations on the TiO2 surface, making I - More adsorbed on the TiO2 surface, making V OC In addition, the improvement of AL1-3|I2|Pt performance in Example 6 can also be attributed to the reduced agglomeration of TiO2 in AL1-3 and the high agglomeration of TiO2 in P25, which destroys the carrier channels between TiO2, and the carriers are mainly transferred in the form of delocalized carriers, which reduces the electron transfer rate. By comparing Examples 6 to 8, it can be seen that with the increase of AL content, J SC First, from the 17.59 mA / cm in Example 7 2 Increased to 25.63 mA / cm in Example 6 2 , and then decreased to 21.67 mA / cm in Example 8 2 Comparing Example 6, Example 9 and Example 10, when AL from different sources is added, the open circuit voltage and effective current density of AL2-3 and AL3-3 in Example 9 and Example 10 are reduced to varying degrees compared with AL1-3 in Example 1. This can be attributed to the fact that the basic units of sinapyl alcohol and coniferyl alcohol in AL2 and AL3 contain more hydroxyl groups, which makes the internal force stronger, and the low crystallinity of TiO2 after adding AL2 and AL3, which leads to increased electron-hole recombination and reduced charge mobility and I on the surface of the photoanode. - concentration, resulting in a decrease in PCE. Fig.23 The dark current of ALx-3|I2|Pt from different sources was tested. Compared with AL1-3|I2|Pt from Example 6, AL2-3|I2|Pt from Example 9 and AL3-3|I2|Pt from Example 10 were -4 mA / cm 2 The voltage value at 400 nm decreased, indicating that the electron recombination rate increased after the addition of AL2 and AL3, and the negative impact on DSSCs increased.

[0236] P25|AL-3|Pt of Example 11 at 100 mW / cm 2The PCE value (9.97%) obtained under illumination is significantly higher than that of DSSCs in Comparative Example 1 (7.20%), indicating that the photoelectric conversion performance is enhanced when AL-3 is used as the electrolyte. SC From 18.15 mA / cm 2 Enhanced to 23.80 mA / cm in Example 11 2 , V OC The voltage of J increased from 0.66V in Comparative Example 1 to 0.75V in Example 11. SC The PCE also shows the same trend of change, which is the same as the change in the hydroxyl strength of the electrolyte. The reverse electron transfer / recombination at the TiO2 / electrolyte interface affects the PCE. The multilayer adsorption of alkyl imidazolium iodide cations in the electrolyte on the surface of the nano-TiO2 porous film can accelerate the transmission of electrons in the nano-porous film and inhibit I - 、I3 - The iodide ion migration will increase the ionic conductivity and help overcome the J caused by pyridine in 4-TBP. SC Adding pyridine to the electrolyte can increase the conduction band edge of TiO2, thereby increasing V OC In addition, as the AL content increases, V OC The V of P25|AL-4|Pt in Example 13 is also gradually increased. OC The V of the DSSCs device increases to 0.80 V, which can be attributed to the fact that the added AL increases the cation concentration in the electrolyte, guides the iodide ions to concentrate on the surface of the photoanode through the ionic interaction force with the iodide ions, suppresses the leakage of photoelectrons, and enhances the V OC .

[0237] Compared with AL / P25|I2|Pt of Examples 6 to 10, P25|AL / I|Pt of Examples 11 to 13, and P25|I2|SL / PEDOT of Examples 1 to 5, the PCE of DSSCs assembled using multiple lignin-modified photoanodes, counter electrodes or electrolytes (P25|AL-3|SL / PEODT of Example 16, AL / P25|I2|SL / PEDOT of Example 18, and AL / P25|AL / I|SL / PEDOT of Example 19) was significantly reduced. At the same time, JSC and VOC did not increase as expected, but instead decreased to varying degrees.

[0238] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and the embodiments. They can be applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily realized.

Claims

1. A method for preparing an alkali lignin modified titanium dioxide photoanode, characterized in that: include: S1, dissolving alkali lignin in ethanol, obtaining a lignin / ethanol mixed solution after ultrasonic stirring, and taking the supernatant after centrifugation to obtain a lignin / ethanol solution; S2, titanium dioxide, ethyl cellulose, and α-pineneol are dissolved in the lignin / ethanol solution prepared in S1, and the photoanode material is obtained after ultrasonic stirring. The mass ratio of the alkali lignin to the ethyl cellulose and titanium dioxide is 1:200:

400.

2. The method for preparing the alkali lignin modified titanium dioxide photoanode according to claim 1, characterized in that: The alkali lignin was derived from wheat straw; and the titanium dioxide used was anatase titanium dioxide with a particle size of 25 nanometers.

3. The method for preparing the alkali lignin modified titanium dioxide photoanode according to claim 2, characterized in that: 3 mg of alkali lignin was added to every 12 ml of ethanol solution, and the prepared alkali lignin-modified titanium dioxide photoanode was named photoanode AL1-3; Alternatively, 4 mg of alkali lignin was added to every 12 ml of ethanol solution, and the prepared alkali lignin-modified titanium dioxide photoanode was named photoanode AL1-4.

4. A method for preparing a sodium lignin sulfonate modified counter electrode, characterized in that: include: S1, 3,4-ethylenedioxythiophene is dissolved in deionized water, and ultrasonic stirring is performed to obtain a 3,4-ethylenedioxythiophene aqueous solution; S2, sodium lignin sulfonate is dissolved in a 3,4-ethylenedioxythiophene aqueous solution, and an SL / EDOT aqueous solution is obtained as an electrodeposition solution after ultrasonic stirring; S3. Use SL / EDOT as the electrodeposition solution, Pt as the counter electrode, FTO conductive substrate as the working electrode, Ag / AgCl as the reference electrode, and prepare the SL / PEDOT counter electrode by constant current electrodeposition at a current of 3.4 mA.

5. The method for preparing a sodium lignin sulfonate modified counter electrode according to claim 4, characterized in that: The mass ratio of 3,4-ethylenedioxythiophene to sodium lignin sulfonate is 1:1.5, and the constant current electrodeposition is continued for 30 seconds to obtain a sodium lignin sulfonate modified counter electrode named counter electrode SL1.5-30s; Or, the mass ratio of 3,4-ethylenedioxythiophene to sodium lignin sulfonate is 1:1.5, the constant current electrodeposition is continued for 15 seconds, and the obtained sodium lignin sulfonate modified counter electrode is named as counter electrode SL1.5-15s; Alternatively, the mass ratio of 3,4-ethylenedioxythiophene to sodium lignin sulfonate is 1:2, the constant current electrodeposition is continued for 30 seconds, and the obtained sodium lignin sulfonate modified counter electrode is named as counter electrode SL2-30s.

6. A method for preparing a lignin derivative modified iodine electrolyte, characterized in that: include: S1, dissolving the lignin derivative in acetonitrile, taking the supernatant after ultrasonic centrifugation to obtain a lignin derivative / acetonitrile solution; S2, valeronitrile, 1-methyl-3-propyl imidazolium iodide, guanidine cyanide sulfate, iodine, and 4-tert-butylpyridine are dissolved in the lignin derivative / acetonitrile solution prepared in S1, and an AL electrolyte is obtained after ultrasonic stirring. The volume ratio of acetonitrile to valeronitrile is 85:15wt%, and the mass ratio of iodine, guanidine cyanide sulfate, 4-tert-butylpyridine, and 1-methyl-3-propyl imidazolium iodide is 42:80:450:1000.

7. The method for preparing the lignin derivative modified iodine electrolyte according to claim 6, characterized in that: The lignin derivative in S1 is alkali lignin.

8. The method for preparing the lignin derivative modified iodine electrolyte according to claim 7, characterized in that: 3 mg of alkali lignin was added to every 10 ml of acetonitrile, and the electrolyte was named AL-3; Or, add 2 mg of alkali lignin to every 10 ml of acetonitrile, named AL-2 electrolyte; Alternatively, 4 mg of alkali lignin was added to every 10 ml of acetonitrile, and the electrolyte was named AL-4.

9. A dye-sensitized solar cell, characterized in that: The method is assembled from any one or more of the alkali lignin modified titanium dioxide photoanode prepared by the preparation method described in claim 3, the sodium lignin sulfonate modified counter electrode prepared by the preparation method described in claim 5, and the lignin derivative modified iodine electrolyte described in claim 8.

10. The dye-sensitized solar cell according to claim 9, characterized in that include: A photoanode, a dye sensitizer, an electrolyte, and a counter electrode; wherein the photoanode, the counter electrode, and the electrolyte are any combination of the following: A: unmodified titanium dioxide photoanode, the counter electrode SL1.5-30s as claimed in claim 5, and unmodified iodine electrolyte; B: unmodified titanium dioxide photoanode, the counter electrode SL1.5-15s as claimed in claim 5, and unmodified iodine electrolyte; C: unmodified titanium dioxide photoanode, the counter electrode SL2-30s according to claim 5, and unmodified iodine electrolyte; D: the photoanode AL1-3 of claim 3, an unmodified Pt counter electrode, and an unmodified iodine electrolyte; E: the photoanode AL1-4 according to claim 3, an unmodified Pt counter electrode, and an unmodified iodine electrolyte; F: unmodified titanium dioxide photoanode, unmodified Pt counter electrode, AL-3 electrolyte according to claim 8; G: unmodified titanium dioxide photoanode, unmodified Pt counter electrode, AL-2 electrolyte according to claim 8; H: unmodified titanium dioxide photoanode, unmodified Pt counter electrode, AL-4 electrolyte according to claim 8; I: the photoanode AL1-3 described in claim 3, the unmodified Pt counter electrode, and the AL-3 electrolyte described in claim 8.

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