Modified cellulose, solar cell interconnection layer and solar cell

Abstract

The present invention relates to the technical field of new materials and solar cells, and discloses a modified cellulose and a solar cell interconnection layer thereof and a solar cell. The modified cellulose is prepared by selectively functionalizing the cellulose side chain region, grafting donor-acceptor functional groups of different structures and sites, and the like. The modified cellulose can be used to prepare the interconnection layer of a double-end stacked solar cell or as an interconnection layer material. The perovskite / organic double-end stacked solar cell includes a wide-bandgap perovskite sub-cell, a modified cellulose interconnection layer, a narrow-bandgap organic sub-cell, and the like, wherein the modified cellulose is spin-coated on the electron transport layer to obtain the interconnection layer. The solution-processable modified cellulose of the present invention, as the interconnection layer of a single-layer single-component perovskite / organic double-end stacked solar cell, significantly improves the photoelectric conversion efficiency of the solar cell, reduces the production process, reduces the production cost, and improves the batch stability of the battery preparation.

Description

Technical Field

[0001] The invention relates to the technical field of new materials and solar cells, and in particular to modified cellulose, a solar cell interconnection layer and a solar cell thereof. Background Art

[0002] Because it breaks through the Shockley-Quesisser (SQ) limit and increases the open circuit voltage (V OC ), and reducing battery production costs, and has attracted widespread attention due to its great potential in future commercial applications. Although perovskite / organic double-terminal tandem solar cells have made great progress in recent years, their photoelectric conversion efficiency is still far from the theoretical limit due to the voltage loss between the perovskite and organic sub-cells caused by their interconnect layer (structure). Therefore, the design and preparation of an interconnect layer (structure) with excellent performance and matching performance is particularly critical for the development of high-performance perovskite / organic double-terminal tandem solar cells.

[0003] In order to achieve excellent optoelectronic properties of perovskite / organic double-terminal tandem solar cells, the interconnect layer (structure) must meet the requirements in terms of optics, electricity and chemistry at the same time, such as: 1. Excellent electrical properties to ensure the extraction, transmission and recombination of carriers within the interconnect layer (structure); 2. Excellent light transmittance to reduce parasitic absorption and reflection losses of the battery; 3. Excellent chemical stability to protect the perovskite film from damage by solvents during subsequent battery preparation.

[0004] At present, one of the commonly used interconnecting layers (structures) of perovskite / organic double-terminal tandem solar cells is a metal oxide (ZnO, SnO x etc.) / elemental metals (Au, Ag, etc.) / metal oxides with hole transport properties (MoOx, NiO x The interconnect layer (structure) in such perovskite / organic double-terminal tandem solar cells is typically prepared using thermal resistance evaporation or atomic layer deposition to form a thin layer of elemental metal, and metal oxides are prepared using sol-gel or thermal resistance evaporation. This interconnect layer (structure) has many shortcomings: 1. Elemental metal layers of 1-2 nm are generally unevenly deposited, resulting in poor film continuity and large errors; 2. Elemental metal easily diffuses into the photoactive layer, causing disordered crystal structure of the film, affecting device efficiency and stability; 3. The interconnect layer structure is complex and requires too many preparation steps; 4. When preparing metal oxides using sol-gel or thermal resistance evaporation, the crystallization of the front cell of the device is destroyed due to subsequent heat treatment; 5. The thickness of the interconnect layer (structure), especially the elemental metal, reduces the permeability of thick films, resulting in a certain degree of parasitic absorption.

[0005] In order to solve the problem of front-cell crystallization caused by the preparation of metal oxides by the sol-gel / thermal resistance evaporation method, patent CN202110681050.0 proposes to use conjugated polymers instead of traditional metal oxides to prepare polymer films at low temperatures, which can avoid the front-cell crystallization caused by high-temperature heat treatment to varying degrees. However, the interconnection layer (structure) of the perovskite / organic double-terminal stacked solar cell developed based on this patent still has the problem of complex interconnection layer structure and too many preparation steps. The use of metal Ag as the intermediate layer of the interconnection structure also does not fundamentally solve the multiple problems existing in its interconnection layer (structure). Summary of the Invention

[0006] To address the common problems in the prior art, such as the difficulty in uniformly depositing thin elemental metals, easy diffusion of elemental metals, complex interconnection layer structures, damage to the crystallization of the front cell in stacked devices due to post-processing of metal oxides, and parasitic absorption of multi-layer interconnection structures, the present invention provides a solution-processable modified cellulose and its application in preparing the interconnection layer of a single-layer, single-component, double-terminal stacked solar cell.

[0007] Another object of the present invention is to provide a method for preparing modified cellulose and its derivatives;

[0008] Another object of the present invention is to provide a double-terminal tandem solar cell;

[0009] Another object of the present invention is to provide a method for preparing a double-terminal stacked solar cell.

[0010] In order to solve the above technical problems, the technical solutions of the present invention are as follows:

[0011] A modified cellulose, the structural formulas of which are:

[0012]

[0013] Wherein, the R1 is selected from: a substituted or unsubstituted C12-C24 heteroaryl group; the heteroaryl group has at least two six-membered ring structures.

[0014] The R2 is selected from: substituted or unsubstituted C7-C24 aryl, substituted or unsubstituted C7-C24 heteroaryl, wherein the heteroaryl has at least two six-membered ring structures.

[0015] Degree of polymerization x=10~200, y=10~200.

[0016] Preferably, the R1 is selected from substituted or unsubstituted C12-C24 heteroaryl groups; the heteroaryl groups include carbazole, diphenylamine, triphenylamine and side chain alkyl substituted derivatives thereof.

[0017] Preferably, R2 is selected from: substituted or unsubstituted C7-C24 heteroaryl; the aryl includes diphenyl sulfone, diphenyl sulfoxide, triphenylphosphine, 1,10-phenanthroline, 4-trifluoromethylbenzene and side chain alkyl substituted derivatives thereof.

[0018] A method for preparing the modified cellulose comprises the following steps:

[0019] In a polar solvent, compound IM-1 was used with and its benzene ring side chain alkyl substituted derivatives The reaction was carried out under the action of catalyst 2 to obtain synthetic compound IM-2;

[0020] In a polar solvent, compound IM-2 is reacted with R2COCl, wherein R2 is By adjusting the feed ratio of compound IM-2 and R2COCl, the reaction produces modified cellulose A or modified cellulose B.

[0021]

[0022] Furthermore, the catalyst 1 is selected from: triphenylphosphine, diphenylphosphine oxide, lithium chloride, lithium bromide, or a combination thereof; the catalyst 2 is selected from: potassium carbonate / sodium, potassium hydroxide / sodium, potassium tert-butoxide / sodium, or a combination thereof.

[0023] Furthermore, to prepare modified cellulose A, the molar ratio of the compound IM-2 to R2COCl is 1:2-4; to prepare modified cellulose B, the molar ratio of the compound IM-2 to R2COCl is 1:0.5-1.2.

[0024] Furthermore, the polar solvent is selected from dimethylformamide (DMAc), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (DM), N-methylmorpholine (DMM), or a combination thereof.

[0025] The present invention provides a cellulose derivative compound having the structural formula:

[0026]

[0027] Wherein, R1 is selected from the following group: a substituted or unsubstituted C12-C24 heteroaryl group, wherein the heteroaryl group has at least two six-membered ring structures; and n is 10-200.

[0028] A method for preparing the cellulose derivative compound comprises the following steps: reacting compound IM-1 with R1 in a polar solvent under the action of catalyst 2 to obtain;

[0029]

[0030] The present invention provides an application of the modified cellulose, which is used for preparing an interconnection layer of a double-terminal stacked solar cell or as an interconnection layer material.

[0031] The present invention also provides a double-terminal stacked solar cell, the structure of which includes two sub-cells and an interconnection layer; the interconnection layer is prepared from the modified cellulose; or is prepared using the modified cellulose as one of the materials.

[0032] Furthermore, the double-end tandem solar cell includes a perovskite / organic double-end tandem solar cell, an organic / organic double-end tandem solar cell, and a perovskite / perovskite double-end tandem solar cell.

[0033] Furthermore, the structure of the perovskite / organic double-terminal tandem solar cell includes a perovskite subcell, an organic subcell, and an interconnect layer. The perovskite subcell includes a perovskite subcell electron transport layer, a perovskite subcell hole transport layer, and a wide-bandgap perovskite layer; the organic subcell includes an organic subcell electron transport layer, an organic subcell hole transport layer, and a narrow-bandgap organic active layer.

[0034] Furthermore, the materials of the wide bandgap perovskite layer, narrow bandgap organic active layer, electron transport layer, hole transport layer, metal electrode and substrate of the perovskite / organic double-terminal tandem solar cell are:

[0035] The material of the wide bandgap perovskite layer includes: methyl bromide lead iodide (MAPbI 3-x Br x , where x≥0.5), cesium iodide-bromoleadate (CsPbI 3-x Br x , where x≥0.5), formamidine iodide-bromolead acid (FAPbI 3-x Br x , where x≥0.5), cesium formamidine bromoiodide lead acid (Cs 1-y FA y PbI 3-x Br x , where x≥0.8), methylformamidine iodide (MA 1-y FA y Pb y I 3-x Br x , where x≥0.8) or a combination thereof.

[0036] The perovskite sub-cell electron transport layer material includes: fullerene C 60 / BCP、C 60 / Phen、PC 61 BM / BCP, PC 61BM / Phen, PC 71 BM / BCP, PC 71 BM / Phen, or a combination thereof.

[0037] The hole transport layer material of the perovskite subcell includes: NiO x 、MoO x , PTAA, Poly-TPD, Spiro-OMeTAD or a combination thereof.

[0038] The material of the narrow bandgap organic active layer includes: poly[2,6-(4,8-bis(5-(2-ethylhexyl)benzo[1,2-b:4,5-b']dithiophene)-(5,5-(1',3'-di-thienyl-5',7'-bis-(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione))] / 3,9 -bis-(2-methylvinyl)-(3-(1,1'-dicyanomethylene)-6 / 7-methyl)-indanone))-5,5,11,11-tetra-(4-hexylphenyl)-dithiophene[2,3-d:2',3'-d]-s-indacenedithiophene[1,2-b:5,6-b'](PBDB-T / IT-M), poly[2,6-(4,8-bis-( 5-(2-ethyl-3-fluorenyl)thienyl)-benzo[1,2-b:4,5-b']dithiophene))-(5,5-(1',3'-di-2-thiophene-5',7'-bis-'(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione](PM6 / Y6), poly[5-(5-(4,8-di-(5- (2-ethylhexyl)-4-fluorothiophene)-6-methylbenzo[1,2-b:4,5-b']dithiophene)-4-(2-butyryl)thiophene)-8-(4-(2-butyryl)-5-methylthienyldithieno[3',2':3,4;2",3":5,6]benzo[1,2-c][1,2,5]thiadiazole] (PM6 / Y6) or a combination thereof.

[0039] The organic sub-battery electron transport layer material includes: PDIN, PDINO, NDI or a combination thereof.

[0040] The hole transport layer material of the organic sub-battery includes: PEDOT:PSS, PVK or a combination thereof.

[0041] The metal electrode material includes: metal aluminum, silver or a combination thereof.

[0042] The substrate material includes: glass, PET, PEN transparent film or a combination thereof.

[0043] Furthermore, the structure of the perovskite / organic double-terminal tandem solar cell includes:

[0044] (a) substrate;

[0045] (b) an ITO transparent conductive layer covering the substrate;

[0046] (c) The hole transport layer of the perovskite subcell is located on the ITO transparent conductive layer;

[0047] (d) A wide-bandgap perovskite layer located on top of the hole-transport layer of the perovskite subcell.

[0048] (e) Perovskite subcell electron transport layer located on the wide-bandgap perovskite layer;

[0049] (f) Interconnect layer located on the electron transport layer of the perovskite subcell;

[0050] (g) an organic subcell hole transport layer located on the interconnect layer;

[0051] (h) a narrow bandgap organic active layer located on the hole transport layer of the organic subcell;

[0052] (i) an organic subcell electron transport layer located on the narrow bandgap organic active layer;

[0053] (j) Metal electrode located on the electron transport layer of the organic subcell.

[0054] Among them, c, d and e are components of perovskite sub-cells, and g, h and i are components of organic sub-cells.

[0055] Furthermore, the perovskite / organic double-terminal tandem solar cell further includes one or more features from bottom to top:

[0056] The thickness of the hole transport layer (c) of the perovskite subcell is 30-50 nm.

[0057] The thickness of the wide bandgap perovskite layer (d) is 500-800 nm,

[0058] The thickness of the electron transport layer (e) of the perovskite subcell is 20-30 nm.

[0059] The thickness of the interconnection layer (f) is 5-15 nm,

[0060] The thickness of the organic sub-battery hole transport layer (g) is 30-40 nm,

[0061] The thickness of the narrow bandgap organic active layer (h) is 90-120 nm,

[0062] The thickness of the organic sub-battery electron transport layer (i) is 10-20 nm.

[0063] Preferably, the thickness of the interconnection layer (f) is 9-12 nm. Preferably, the thickness of the interconnection layer (f) is 12 nm.

[0064] The present invention provides a method for preparing the perovskite / organic double-terminal tandem solar cell, comprising the following steps:

[0065] The substrate is an ITO transparent conductive layer, and the perovskite sub-cell hole transport layer is coated on the ITO transparent conductive layer using a wet processing technology;

[0066] The wide bandgap perovskite layer is deposited on the perovskite subcell hole transport layer using a solution preparation process;

[0067] The perovskite sub-cell electron transport layer is deposited on the wide bandgap perovskite layer using a wet processing process;

[0068] The interconnect layer is deposited on the electron transport layer of the perovskite sub-cell by a solution processing process;

[0069] The organic sub-battery hole transport layer is deposited on the interconnect layer using a wet processing process;

[0070] The narrow bandgap organic active layer is deposited on the organic sub-cell hole transport layer using a solution preparation process;

[0071] The organic sub-battery electron transport layer is deposited on the narrow bandgap organic active layer using a wet processing process;

[0072] The metal electrode is deposited on the electron transport layer of the organic sub-cell by vacuum coating to prepare the electrode, thereby obtaining the perovskite / organic double-terminal stacked solar cell.

[0073] Furthermore, the hole transport layer, wide bandgap perovskite layer, interconnect layer, narrow bandgap organic active layer, and electron transport layer are all prepared using a solution processing process to form corresponding thin films, and their thickness is controlled by controlling the spin coating rate and material concentration.

[0074] A method for preparing the perovskite / organic double-terminal tandem solar cell comprises the following steps:

[0075] Providing a substrate having an ITO transparent conductive layer;

[0076] Depositing the perovskite sub-cell hole transport layer material on the ITO transparent conductive layer to form a perovskite sub-cell hole transport layer;

[0077] Depositing the wide bandgap perovskite layer material on the perovskite sub-cell hole transport layer to form a wide bandgap perovskite layer;

[0078] Depositing the perovskite sub-cell electron transport layer material on the wide bandgap perovskite layer to form a perovskite sub-cell electron transport layer;

[0079] depositing the modified cellulose material on the electron transport layer of the perovskite sub-cell to form an interconnection layer;

[0080] Depositing the organic sub-battery hole transport layer material on the interconnect layer to form an organic sub-battery hole transport layer;

[0081] Depositing the narrow-bandgap organic active layer material on the organic sub-battery hole transport layer to form a narrow-bandgap organic active layer;

[0082] Depositing the organic sub-battery electron transport layer material on the narrow bandgap organic active layer to form an organic sub-battery electron transport layer;

[0083] The metal electrode material is deposited on the electron transport layer of the organic sub-battery to form an electrode.

[0084] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0085] The present invention innovatively uses modified cellulose as a single-layer, single-component interconnecting layer of a double-terminal stacked solar cell. By selectively functionalizing the cellulose side chain regions and grafting donor-acceptor functional groups of different structures and sites, the conjugated blocking effect of the cellulose pyranose ring is utilized to inhibit the interaction between the donor-acceptor structural units. At the same time, the remaining hydroxyl groups of cellulose are utilized to capture carriers for recombination, thereby achieving "bipolar" independent transmission and recombination of carriers by the modified cellulose.

[0086] The interconnection layer prepared by the present invention solves the problems commonly existing in the prior art, such as the thin thickness of the elemental metal making it difficult to deposit evenly, the easy diffusion of the elemental metal, the complex structure of the interconnection layer, the post-treatment of the metal oxide destroying the crystallization of the front cell in the stacked device, and the parasitic absorption of the multi-layer interconnection structure.

[0087] The interconnection layer prepared by the present invention solves the problems of complicated production process, high production cost and poor batch stability of traditional multi-layer structures through a single-layer and single-component design. BRIEF DESCRIPTION OF THE DRAWINGS

[0088] Figure 1 Schematic diagram of the structure of cellulose-based interconnected layer perovskite / organic tandem solar cell;

[0089] Figure 2 The JV characteristics of trifluorotoluene-substituted-6-carbazole cellulose-based interconnect layer stacked cells. DETAILED DESCRIPTION

[0090] The present invention will be further described below in conjunction with the accompanying drawings and specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0091] Unless otherwise specified, the reagents and materials used in the following examples were commercially available.

[0092] Example 1

[0093] In this embodiment, the structural formula of modified cellulose A1 is:

[0094]

[0095] The preparation method of modified cellulose A1 comprises the following steps:

[0096] Step 1: Synthesis of compound IM-1, 6-bromocellulose

[0097] 2 parts by weight of microcrystalline cellulose, 10 parts by weight of NBS, 0.5 parts by weight of triphenylphosphine, 1 part by weight of lithium bromide, and 20 parts by weight of DMAc were placed in a three-necked round-bottom flask under argon. The mixture was heated to 70°C and allowed to react for 2 hours. The reaction was then terminated and the reaction mixture was slowly poured into 50 parts by weight of methanol and deionized water. The mixture was filtered and washed three times with methanol to collect the residue. The residue was then dissolved in 30 parts of THF, recrystallized from ethanol, and filtered to obtain a pale yellow solid. This was then dried under vacuum to obtain compound IM-1 with a yield of 63%.

[0098] Step 2: Synthesis of compound IM-2, 6-carbazolylcellulose

[0099] 1 part (by mass) of compound IM-1, 1 part (by mass) of carbazole, 4 parts (by mass) of potassium carbonate, and 10 parts (by mass) of DMP were placed in a 100 mL three-necked round-bottom flask under nitrogen. 3 parts (by mass) of NMM were injected, stirred for 0.5 h, heated to 60°C, and reacted for 10 h. After the reaction, 10 equivalents of deionized water were added to the three-necked round-bottom flask, producing a large amount of white precipitate. This was filtered to obtain a white precipitate, which was redissolved in ethanol, collected by filtration, and dried under vacuum. The yield was 71%.

[0100] Step 3: Synthesis of modified cellulose A1

[0101] 1 part (by mass) of compound IM-2, 3 parts (by mass) of 4-trifluoromethylbenzoyl chloride, and 5 parts (by mass) of DMF were placed in a 100 mL three-necked flask under nitrogen atmosphere at 60°C for 4 hours. After the reaction, 5 parts (by mass) of deionized water were added to the round-bottom flask, producing a large amount of white precipitate. This was filtered and washed three times with methanol. The white precipitate was then redissolved in THF, and the supernatant was collected by filtration and spin-dried. The white solid was collected, washed three times with ethanol, and dried under vacuum. The yield was 69%.

[0102] FT-IR (cm -1 ):3454,3012,2983,2843,2594,2501,2445,1757,1644,1545,1484,1375,1252,1211; 1 H NMR: 11.3(s,-OH),8.08(dd,J=8.42Hz,-Ph),7.83(d,J=8.56Hz,-Ph),7.45(d,J =8.48Hz,-Ph),7.35(d,J=8.4Hz,-Ph),7.28(d,J=8.46Hz,-Ph),2.52(s,-CH2-); 19 F NMR: 8.74; Elemental analysis: N, 2.45%; Degree of substitution: 2.85. Example 2

[0103] In this embodiment, the structural formula of modified cellulose B1 is:

[0104]

[0105] The preparation method of modified cellulose B1 comprises the following steps:

[0106] Step 1: Synthesis of modified cellulose B1

[0107] 1 part (by mass) of compound IM-2 prepared in Example 1, 1 part (by mass) of 4-trifluoromethylbenzoyl chloride, and 3 parts (by mass) of DMF were placed in a 100 mL three-necked flask under nitrogen atmosphere at 60°C for 2 hours. After completion of the reaction, 3 parts (by mass) of deionized water were added to the round-bottom flask, producing a large amount of white precipitate. This was filtered and washed three times with methanol. The white precipitate was then redissolved in THF, and the supernatant was collected by filtration and spin-dried. The white solid was collected, washed three times with ethanol, and dried under vacuum. The yield was 58%.

[0108] FT-IR (cm -1 ):3423,3032,2994,2873,2579,2523,2434,1741,1664,1534,1496,1388,1274,1206; 1H NMR: 11.25(s,-OH),8.05(d,J=8.22Hz,-Ph),7.81(d,J=8.48Hz,-Ph),7.41(d,J= 8.36Hz,-Ph),7.31(d,J=8.46Hz,-Ph),7.25(d,J=8.42Hz,-Ph),2.56(s,-CH2-); 19 F NMR: 8.74; elemental analysis: N, 3.69%; degree of substitution: 0.96.

[0109] Example 3

[0110] In this embodiment, the structural formula of modified cellulose A2 is:

[0111]

[0112] The preparation method of modified cellulose A2 comprises the following steps:

[0113] Step 1: Synthesis of compound IM-1,6-bromocellulose

[0114] Weigh 1 part by weight of microcrystalline cellulose, 5 parts by weight of NBS, 0.25 parts by weight of triphenylphosphine, 0.5 parts by weight of lithium bromide and 20 parts by weight of DM S O was placed in a three-necked round-bottom flask under argon protection and heated to 70°C for 1 hour. The reaction was stopped and the reaction mixture was slowly poured into 25 parts by weight of methanol and deionized water. The precipitate was filtered and washed three times with methanol to collect the filter residue. The filter residue was then dissolved in 30 parts of THF and recrystallized from ethanol. A light yellow solid was filtered and dried in vacuo to obtain the compound of formula IM-1 in a yield of 65%.

[0115] Step 2: Synthesis of compound IM-2,6-diphenylaminocellulose

[0116] 2 parts (by mass) of compound IM-1, 2 parts (by mass) of diphenylamine, 8 parts (by mass) of sodium carbonate, and 20 parts (by mass) of NMM were placed in a 250 mL three-necked round-bottom flask under nitrogen. 6 parts (by mass) of NMM were added, stirred for 1 hour, heated to 60°C, and allowed to react for 15 hours. After the reaction, 20 equivalents of deionized water were added to the three-necked round-bottom flask, producing a large amount of white precipitate. This was filtered to obtain a white precipitate, which was redissolved in ethanol, collected by filtration, and dried under vacuum. The yield was 69%.

[0117] Step 3: Synthesis of modified cellulose A2

[0118] 2 parts (by mass) of compound IM-2, 6 parts (by mass) of 4-trifluoromethylbenzoyl chloride, and 10 parts (by mass) of DMF were placed in a 250 mL three-necked flask under nitrogen atmosphere at 60°C for 8 hours. After the reaction, 10 parts (by mass) of deionized water were added to the round-bottom flask, producing a large amount of white precipitate. This was filtered and washed three times with methanol. The white precipitate was then redissolved in THF, and the supernatant was collected by filtration and spin-dried. The white solid was collected, washed three times with ethanol, and dried under vacuum. The yield was 64%.

[0119] FT-IR (cm -1 ):3407,3046,2991,2872,2583,2517,2462,1742,1634,1592,1498,1396,1216,1206; 1 H NMR: 11.5(s,-OH),8.12(d,J=8.38Hz,-Ph),8.02(d,J=8.38Hz,-Ph),7.79-7.74(m,-Ph),7 .39(d,J=8.64Hz,-Ph),7.24(d,J=8.46Hz,-Ph),7.21(d,J=8.48Hz,-Ph),2.54(s,-CH2-); 19 F NMR: 8.68; elemental analysis: N, 2.58%; degree of substitution: 2.91.

[0120] Example 4

[0121] In this embodiment, the structural formula of modified cellulose B2 is:

[0122]

[0123] The preparation method of modified cellulose B2 comprises the following steps:

[0124] Step 1: Synthesis of modified cellulose B2

[0125] Two parts (by mass) of compound IM-2, two parts (by mass) of 4-trifluoromethylbenzoyl chloride, and six parts (by mass) of DMF were placed in a 250 mL three-necked flask under nitrogen and reacted at 60°C for 4 hours. After the reaction, six parts (by mass) of deionized water were added to the round-bottom flask, producing a large amount of white precipitate. This was filtered and washed three times with methanol. The white precipitate was then redissolved in THF, and the supernatant was collected by filtration and spin-dried. The white solid was collected, washed three times with ethanol, and dried under vacuum. The yield was 54%.

[0126] FT-IR (cm -1):3415,3023,2988,2864,2558,2511,2416,1736,1627,1512,1484,1375,1259,1213; 1 H NMR:11.33(s,-OH),8.10(d,J=8.46Hz,-Ph),8.01(d,J=8.34Hz,-Ph),7.76-7.72(m,-Ph), 7.36(d,J=8.48Hz,-Ph), 7.22(d,J=8.42Hz,-Ph), 7.19(d,J=8.42Hz,-Ph), 2.56(s,-CH2-); 19 F NMR: 8.69; elemental analysis: N, 3.86%; degree of substitution: 0.94.

[0127] Example 5

[0128] In this embodiment, the structural formula of modified cellulose A3 is:

[0129]

[0130] Step 1: Synthesis of compound IM-1,6-bromocellulose

[0131] Weigh 3 parts by weight of microcrystalline cellulose, 15 parts by weight of NBS, 0.75 parts by weight of triphenylphosphine, 1.5 parts by weight of lithium bromide and 60 parts by weight of DM P Place the mixture in a three-necked round-bottom flask under argon protection and heat to 80°C for 3 hours. After stopping the reaction, slowly pour the reaction mixture into 75 parts by weight of methanol and deionized water. Filter the precipitate and wash it three times with methanol to collect the filter residue. Next, dissolve the filter residue in 90 parts of THF, recrystallize it from ethanol, filter and obtain a pale yellow solid, and dry it in vacuo to obtain the compound of formula IM-1 in a yield of 54%.

[0132] Step 2: Synthesis of compound IM-2,6-triphenylaminocellulose

[0133] 3 parts (by mass) of compound IM-1, 3 parts (by mass) of a triphenylamine derivative, 12 parts (by mass) of potassium hydroxide / sodium hydroxide, and 30 parts (by mass) of DMSO were placed in a 500 mL three-necked round-bottom flask under nitrogen. 9 parts (by mass) of DMSO was added, stirred for 2 hours, and then heated to 70°C and allowed to react for 20 hours. After the reaction, 30 equivalents (by mass) of deionized water were added to the flask, producing a large amount of light yellow precipitate. This was filtered to obtain a light yellow precipitate, which was redissolved in ethanol, collected by filtration, and dried under vacuum. The yield was 52%.

[0134] Step 3: Synthesis of modified cellulose A3

[0135] 3 parts (by mass) of compound IM-2, 9 parts (by mass) of diphenylsulfone-4-carbonyl chloride, and 15 parts (by mass) of DMF were placed in a 500 mL three-necked flask under nitrogen atmosphere at 65°C for 12 hours. After the reaction, 15 parts (by mass) of deionized water were added to the round-bottom flask, producing a large amount of light yellow precipitate. This was filtered and washed three times with methanol. The light yellow precipitate was then redissolved in THF, and the supernatant was collected by filtration and spin-dried. The light yellow solid was collected, washed three times with ethanol, and dried under vacuum. The yield was 56%.

[0136] FT-IR (cm -1 ):3443,3025,2986,2835,2558,2508,2448,1738,1627,1589,1501,1403,1227,1201; 1 H NMR: 10.9 (s, -OH), 8.05 (d, J = 8.38 Hz, -Ph), 8.01 (d, J = 8.36 Hz, -Ph), 7.97 (d, J = 8.48 Hz, -Ph), 7.91 (d, J = 8.64 Hz, -Ph), 7.84 (d, J = 8.64 Hz, -Ph), 7.76-7.72 (m, -Ph), 7.47 (d, J = 8.58 Hz, -Ph), 7.26 (d, J = 8.32 Hz, -Ph), 7.19 (d, J = 8.42 Hz, -Ph), 2.48 (s, -CH2-); elemental analysis: N, 2.42%; degree of substitution: 2.94.

[0137] Example 6

[0138] In this embodiment, the structural formula of modified cellulose B3 is:

[0139]

[0140] Step 1: Synthesis of modified cellulose B3

[0141] 3 parts (by mass) of compound IM-2, 3 parts (by mass) of diphenylsulfone-4-carbonyl chloride, and 9 parts (by mass) of DMF were placed in a 500 mL three-necked flask under nitrogen atmosphere at 65°C for 6 hours. After the reaction, 9 parts (by mass) of deionized water were added to the round-bottom flask, producing a large amount of light yellow precipitate. This was filtered and washed three times with methanol. The light yellow precipitate was then redissolved in THF, and the supernatant was collected by filtration and spin-dried. The light yellow solid was collected, washed three times with ethanol, and dried under vacuum. The yield was 52%.

[0142] FT-IR (cm -1):3406,3011,2984,2853,2547,2503,2427,1732,1631,1527,1495,1399,1246,1205; 1 H NMR: 10.25 (s, -OH), 8.02 (d, J = 8.44 Hz, -Ph), 7.99 (d, J = 8.48 Hz, -Ph), 7.88 (d, J = 8.52 Hz, -Ph), 7.79-7.74 (m, -Ph), 7.45 (d, J = 8.42 Hz, -Ph), 7.22 (d, J = 8.40 Hz, -Ph), 7.17 (d, J = 8.38 Hz, -Ph), 2.52 (s, -CH2-); Elemental analysis: N, 2.95%; degree of substitution: 0.92.

[0143] Example 7

[0144] In this embodiment, the structural formula of modified cellulose A4 is:

[0145]

[0146] Step 1: Synthesis of compound IM-1,6-bromocellulose

[0147] 4 parts by weight of microcrystalline cellulose, 20 parts by weight of NBS, 1 part by weight of triphenylphosphine, 2 parts by weight of lithium bromide, and 80 parts by weight of DMP were placed in a three-necked round-bottom flask, protected by argon, heated to 75°C, and reacted for 4 hours. The reaction was stopped, and the reaction mixture was slowly poured into 100 parts by weight of methanol and deionized water. The bottom was filtered and washed three times with methanol to collect the filter residue. The filter residue was then dissolved in 120 parts of THF, recrystallized in ethanol, filtered to obtain a white solid, and vacuum dried to obtain the compound of formula IM-1 with a yield of 69%.

[0148] Step 2: Synthesis of compound IM-2,6-(4',4"-diethyl)-diphenylaminocellulose

[0149] 4 parts by mass of compound IM-1, 4 parts by mass of 4',4"-diethyl-diphenylamine, 152 parts of potassium tert-butoxide, and 40 parts of DMP were placed in a 500 mL three-necked round-bottom flask under nitrogen protection. 12 parts of DMP were injected, stirred for 4 hours, heated to 75°C, and reacted for 24 hours. After the reaction, 40 equivalents of deionized water were added to the three-necked round-bottom flask, producing a large amount of white precipitate. The white precipitate was filtered and redissolved in ethanol. The precipitate was collected by filtration and dried in vacuo. The yield was 64%.

[0150] Step 3: Synthesis of modified cellulose A4

[0151] 4 parts (by mass) of compound IM-2, 12 parts (by mass) of triphenylphosphine-4-carbonyl chloride, and 20 parts (by mass) of DMF were placed in a 500 mL three-necked flask under nitrogen atmosphere at 70°C for 15 hours. After the reaction, 20 parts (by mass) of deionized water were added to the round-bottom flask, producing a large amount of light yellow precipitate. This was filtered and washed three times with methanol. The light yellow precipitate was then redissolved in THF, and the supernatant was collected by filtration and spin-dried. The light yellow solid was collected, washed three times with ethanol, and dried under vacuum. The yield was 53%.

[0152] FT-IR (cm -1 ):341,3017,2991,2846,2541,2513,2439,1731,1625,1594,1504,1401,1220,1213; 1 H NMR: 10.82(s,-OH),8.12(d,J=8.46Hz,-Ph),8.08(d,J=8.48Hz,-Ph),8.04(d,J=8.56Hz,-Ph),7.94(d, J=8.42Hz,-Ph),7.88(d,J=8.48Hz,-Ph),7.81(d,J=8.36Hz,-Ph),7.78(d,J=8.42Hz,-Ph),7.74-7.71( m, -Ph), 7.51(d, J=8.52Hz, -Ph), 7.46(d, J=8.46Hz, -Ph), 7.22(d, J=8.46Hz, -Ph), 7.17(d, J=8.28Hz, -Ph), 2.51(s, -CH2-), 1.02(dd, J=4.62Hz, -CH2-), 0.88(t, J=4.52Hz, -CH3); Elemental analysis: N, 2.18%; Degree of substitution is 2.88.

[0153] Example 8

[0154] In this embodiment, the structural formula of modified cellulose B4 is:

[0155]

[0156] Step 1: Synthesis of modified cellulose B4

[0157] Weigh 4 parts of compound IM-2, 4 parts of (4',4"-diethyl)diphenylamine-4-carbonyl chloride, and 12 parts of DMF into a 500 mL three-necked flask under nitrogen protection and react at 70°C for 9 hours. After the reaction, 12 parts of deionized water were added to the round-bottom flask to produce a large amount of light yellow precipitate, which was filtered and washed three times with methanol. After that, the light yellow precipitate was redissolved in THF, and the lower supernatant was collected by filtration. The light yellow solid was collected by spin drying and washed three times with ethanol. The yield was 55%.

[0158] FT-IR (cm -1 ):3422,3009,2991,2849,2551,2517,2419,1735,1624,1515,1499,1398,1227,1204; 1 H NMR: 10.52(s,-OH),8.10(d,J=8.42Hz,-Ph), 8.04(d,J=8.46Hz,-Ph), 8.02(d,J=8.62Hz,-Ph), 7.91(d,J=8.38Hz,-Ph),7.84(d,J=8.42Hz,-Ph),7.79-7.72(m,-Ph),7.68-7.64(m,-Ph),7.49( d, J = 8.48 Hz, -Ph), 7.42 (d, J = 8.40 Hz, -Ph), 7.20 (d, J = 8.32 Hz, -Ph), 7.16 (d, J = 8.38 Hz, -Ph), 2.54 (s, -CH2-), 1.04 (dd, J = 4.68 Hz, -CH2-), 0.89 (t, J = 4.58 Hz, -CH3); Elemental analysis: N, 2.47%; Degree of substitution is 0.94.

[0159] Example 9

[0160] In this embodiment, the structural formula of modified cellulose A5 is:

[0161]

[0162] Step 1: Synthesis of compound IM-1,6-bromocellulose

[0163] 1 part by weight of microcrystalline cellulose, 5 parts by weight of NBS, 0.25 parts by weight of triphenylphosphine, 0.5 parts by weight of lithium bromide, and 20 parts by weight of NMM were placed in a three-necked round-bottom flask under argon protection. The mixture was heated to 75°C and allowed to react for 1 hour. The reaction was then terminated, and the reaction mixture was slowly poured into 25 parts by weight of methanol and deionized water. The mixture was filtered and washed three times with methanol to collect the residue. The residue was then dissolved in 30 parts of THF, recrystallized in ethanol, and filtered to obtain a pale yellow solid. The solid was then dried under vacuum to obtain the compound of formula IM-1 in a yield of 62%.

[0164] Step 2: Synthesis of compound IM-2,6-(4',4")-diethyl-carbazolylcellulose

[0165] 1 part of compound IM-1, 1 part of (4',4")-diethyl-carbazole, 4 parts of sodium tert-butoxide, and 10 parts of NMM were placed in a 250 mL three-necked round-bottom flask under nitrogen protection. 3 parts of NMM were injected, stirred for 1 hour, heated to 75°C, and reacted for 10 hours. After the reaction, 10 equivalents of deionized water were added to the three-necked round-bottom flask to produce a large amount of light yellow precipitate. The light yellow precipitate was filtered and redissolved in ethanol. The precipitate was collected by filtration and dried in vacuo. The yield was 57%.

[0166] Step 3: Synthesis of modified cellulose A5

[0167] Weigh 1 part of compound IM-2, 3 parts of 1,10-phenanthroline-4-carbonyl chloride, and 5 parts of DMF into a 250 mL three-necked flask under nitrogen and react at 70°C for 5 hours. After the reaction, add 5 parts of deionized water to the round-bottom flask, producing a large amount of light yellow precipitate. This was filtered and washed three times with methanol. The light yellow precipitate was then redissolved in THF, and the supernatant was collected by filtration and spin-dried. The light yellow solid was collected, washed three times with ethanol, and dried under vacuum. The yield was 52%.

[0168] FT-IR (cm -1 ):3457,3031,2991,2824,2543,2512,2453,1736,1633,1599,15071,1401,1236,1208; 1H NMR: 11.21(s,-OH),8.13(d,J=8.44Hz,-Ph),8.09(d,J=8.48Hz,-Ph),8.03(d,J=8.48Hz,- Ph),7.99(d,J=8.42Hz,-Ph),7.95(d,J=8.52Hz,-Ph),7.88(d,J=8.40Hz,-Ph),7.78-7.73 (m, -Ph), 7.42 (d, J = 8.46 Hz, -Ph), 7.23 (d, J = 8.48 Hz, -Ph), 7.15 (d, J = 8.48 Hz, -Ph), 2.54 (s, -CH2-), 1.06 (dd, J = 4.62 Hz, -CH2-), 0.88 (t, J = 4.52 Hz, -CH3); Elemental analysis: N, 3.14%; Degree of substitution is 2.92.

[0169] Example 10

[0170] In this embodiment, the structural formula of modified cellulose B5 is:

[0171]

[0172] Step 1: Synthesis of modified cellulose B5

[0173] Weigh 1 part (by mass) of compound IM-2, 1 part (by mass) of 1,10-phenanthroline-4-carbonyl chloride, and 3 parts (by mass) of DMF into a 250 mL three-necked flask under nitrogen and react at 70°C for 2 hours. After the reaction, add 3 parts (by mass) of deionized water to the round-bottom flask, producing a large amount of light yellow precipitate. This was filtered and washed three times with methanol. The light yellow precipitate was then redissolved in THF, and the supernatant was collected by filtration and spin-dried. The light yellow solid was collected, washed three times with ethanol, and dried under vacuum. The yield was 55%.

[0174] FT-IR (cm -1 ):3443,3017,2989,2844,2541,2514,2431,1731,1629,1595,1497,1398,1238,1201; 1H NMR: 11.05(s,-OH),8.10(d,J=8.48Hz,-Ph),8.07(d,J=8.42Hz,-Ph),8.01(d,J=8.44Hz,- Ph),7.96(d,J=8.46Hz,-Ph),7.92(d,J=8.42Hz,-Ph),7.82(d,J=8.44Hz,-Ph),7.76-7.71 (m, -Ph), 7.45 (d, J = 8.48 Hz, -Ph), 7.22 (d, J = 8.42 Hz, -Ph), 7.14 (d, J = 8.44 Hz, -Ph), 2.52 (s, -CH2-), 1.05 (dd, J = 4.64 Hz, -CH2-), 0.87 (t, J = 4.56 Hz, -CH3); Elemental analysis: N, 2.91%; Degree of substitution is 0.92.

[0175] Example 11

[0176] This embodiment provides a method for preparing a perovskite / organic double-terminal tandem solar cell with a modified cellulose-based interconnect layer.

[0177] Modified cellulose can be used in the interconnect layer of perovskite / organic double-terminal tandem solar cells.

[0178] The battery has a layered structure, such as Figure 1 As shown, the substrate to the electrode includes, in sequence, a substrate 1, an ITO transparent conductive layer 2, a perovskite sub-cell hole transport layer 3, a wide bandgap perovskite layer 4, a perovskite sub-cell electron transport layer 5, an interconnection layer 6, an organic sub-cell hole transport layer 7, a narrow bandgap organic active layer 8, an organic sub-cell hole transport layer 9, and a metal electrode 10.

[0179] The substrate 1 is made of glass or a transparent flexible film; the ITO transparent conductive layer 2 is made of indium-doped tin oxide with a sheet resistance of 10-15Ω / sq;

[0180] After cleaning the substrate with the ITO transparent conductive layer, it was treated with plasma in air for 10 minutes; then it was transferred to a glove box and a 40nm perovskite subcell hole transport layer 3 (PTAA) was spin-coated on it.

[0181] After the annealing treatment, a 600nm wide bandgap perovskite layer 4 (CsPbI 3-x Br x ), annealed for 30 min; then, a 20 nm perovskite subcell electron transport layer 5 (PC 61 BM / BCP) is spin-coated onto the wide bandgap perovskite layer;

[0182] Next, the modified cellulose material was spin-coated to prepare the interconnection layer 6, and then annealed to obtain the interconnection layer of the perovskite / organic double-terminal stacked cell with a thickness of 12 nm.

[0183] Then, a 35nm thick organic sub-cell hole transport layer 7 (PEDOT:PSS) was spin-coated on top of it and annealed;

[0184] Then, a 100 nm narrow bandgap organic active layer 8 (D18: Y6-Cl) is spin-coated onto the organic sub-cell hole transport layer 7 to form the second active layer of the stacked cell.

[0185] Then, a 15 nm thick organic sub-battery electron transport layer 9 (PDIN) is spin-coated on the narrow bandgap organic active layer 8;

[0186] Finally, a metal electrode 10 is deposited on the organic electron transport layer. Metal silver is selected and the thickness thereof is 100 nm.

[0187] Example 12

[0188] This embodiment provides a method for preparing a perovskite / organic double-terminal tandem solar cell with a modified cellulose-based interconnect layer.

[0189] In order to explore the factors affecting the thickness of the modified cellulose interconnection layer, this comparative experiment mainly adjusted the thickness of the modified cellulose interconnection layer.

[0190] The battery preparation method and materials adopt the same process and process as Example 11, except that the thickness of the modified cellulose interconnect layer A1 is adjusted to 5nm.

[0191] The battery has a layered structure, such as Figure 1 As shown, the substrate to the electrode includes, in sequence, a substrate 1, an ITO transparent conductive layer 2, a perovskite sub-cell hole transport layer 3, a wide bandgap perovskite layer 4, a perovskite sub-cell electron transport layer 5, an interconnection layer 6, an organic sub-cell hole transport layer 7, a narrow bandgap organic active layer 8, an organic sub-cell hole transport layer 9, and a metal electrode 10.

[0192] Example 13

[0193] Thickness of Modified Cellulose Interconnect Layer This embodiment provides a method for preparing a perovskite / organic double-terminal tandem solar cell with a modified cellulose-based interconnect layer.

[0194] In order to explore the factors affecting the thickness of the modified cellulose interconnection layer, this comparative experiment mainly adjusted the thickness of the modified cellulose interconnection layer.

[0195] The battery preparation method and materials adopt the same process and process as Example 11, except that the thickness of the modified cellulose interconnect layer A1 is adjusted to 15nm.

[0196] The battery has a layered structure, such as Figure 1 As shown, the substrate to the electrode includes, in sequence, a substrate 1, an ITO transparent conductive layer 2, a perovskite sub-cell hole transport layer 3, a wide bandgap perovskite layer 4, a perovskite sub-cell electron transport layer 5, an interconnection layer 6, an organic sub-cell hole transport layer 7, a narrow bandgap organic active layer 8, an organic sub-cell hole transport layer 9, and a metal electrode 10.

[0197] Example 14

[0198] Thickness of Modified Cellulose Interconnect Layer This embodiment provides a method for preparing a perovskite / organic double-terminal tandem solar cell with a modified cellulose-based interconnect layer.

[0199] In order to explore the factors affecting the thickness of the modified cellulose interconnection layer, this comparative experiment mainly adjusted the thickness of the modified cellulose interconnection layer.

[0200] The battery preparation method and materials adopt the same process and process as Example 11, except that the thickness of the modified cellulose interconnect layer A1 is adjusted to 9nm.

[0201] The battery has a layered structure, such as Figure 1 As shown, the substrate to the electrode includes, in sequence, a substrate 1, an ITO transparent conductive layer 2, a perovskite sub-cell hole transport layer 3, a wide bandgap perovskite layer 4, a perovskite sub-cell electron transport layer 5, an interconnection layer 6, an organic sub-cell hole transport layer 7, a narrow bandgap organic active layer 8, an organic sub-cell hole transport layer 9, and a metal electrode 10.

[0202] Comparative Example 1

[0203] This embodiment provides a method for preparing a perovskite / organic double-terminal tandem solar cell with a modified cellulose-based interconnect layer.

[0204] In order to explore the influence of the thickness of the modified cellulose interconnection layer, this comparative experiment mainly adjusted the preparation of the traditional multilayer interconnection structure.

[0205] The battery preparation method and materials adopt the same process and procedures as Example 11, except that the modified cellulose interconnection layer is replaced with a traditional step-by-step multilayer structure, and its structure is: SnOx / Ag / MoOx.

[0206] The battery has a layered structure, such as Figure 1 As shown, the substrate to the electrode includes, in sequence, a substrate 1, an ITO transparent conductive layer 2, a perovskite sub-cell hole transport layer 3, a wide bandgap perovskite layer 4, a perovskite sub-cell electron transport layer 5, an interconnection layer 6, an organic sub-cell hole transport layer 7, a narrow bandgap organic active layer 8, an organic sub-cell hole transport layer 9, and a metal electrode 10.

[0207] Among them, in the interconnection structure SnOx / Ag / MoOx:

[0208] SnOx is grown by atomic layer deposition with a thickness of 10nm;

[0209] The metal element Ag is deposited by atomic layer deposition with a thickness of 1nm

[0210] MoOx is formed into a film using high vacuum thermal evaporation with a thickness of 10nm.

[0211] Performance testing:

[0212] During the preparation process, the thickness of the spin-coated film was measured using a profilometer, and the photoelectric conversion performance of the battery was tested using a Newport solar simulator combined with a Keithley 2400 digital source meter.

[0213] The performance of the above perovskite / organic double-terminal tandem solar cells is shown in Table 1 and Figure 2 As shown in .

[0214] Table 1 Performance parameters of perovskite / organic double-terminal tandem solar cells in Example 5

[0215]

[0216]

[0217] Table 1 shows the performance parameters of perovskite / organic double-terminal tandem solar cells. From Table 1, it can be found that the short-circuit current (J SC ), open circuit voltage (V OC ) and fill factor (FF) are significantly higher than those of the cell based on the low-substitution modified cellulose interconnect layer, and the corresponding photoelectric conversion efficiency also shows similar phenomena. More importantly, compared with Comparative Example 1, the short-circuit current of the cell using the traditional step-by-step multilayer SnOx / Ag / MoOx structure is significantly lower than that of the cell based on the high-substitution modified cellulose interconnect layer, while other parameters are basically the same as those of the cell based on the high-substitution modified cellulose interconnect layer, indicating that the SnOx / Ag / MoOx interconnect layer structure has some parasitic absorption.

[0218] Furthermore, by preparing A1-based batteries with different thicknesses of modified cellulose interconnect layers, the effect of the thickness of the modified cellulose interconnect layer was explored. The results showed that as the thickness of the interconnect layer increased from 5nm to 15nm, the short-circuit current (J SC ) and open circuit voltage (V OC ) first increases and then decreases. When its thickness is 12nm, the battery shows the best photoelectric properties, such as Figure 2 As shown, its short-circuit current (J SC ), open circuit voltage (VOC ), and the fill factor (FF) are: 14.95mA / cm 2 , 1.85V, and 78.65%, the corresponding photoelectric conversion efficiency is 21.75%, which is significantly better than the comparative example. At the same time, the battery exhibits low hysteresis, such as Figure 2 As shown, the forward and reverse scans are performed only when the short circuit current (J SC ) and fill factor, with a hysteresis rate of only 2.54%.

[0219] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A modified cellulose, characterized in that The modified cellulose structural formulas are: Wherein, R1 is selected from: a substituted or unsubstituted C12-C24 heteroaryl group, wherein the heteroaryl group has at least two six-membered ring structures; R2 is selected from: substituted or unsubstituted C7-C24 heteroaryl, wherein the heteroaryl has at least two six-membered ring structures; Degree of polymerization x=10-200, y=10-200; The heteroaryl groups include carbazole, diphenylamine, triphenylamine, diphenyl sulfone, diphenyl sulfoxide, triphenylphosphine oxide, 1,10-phenanthroline, 4-trifluoromethylbenzene and side chain alkyl substituted derivatives thereof.

2. A method for preparing the modified cellulose according to claim 1, characterized in that: The following steps are involved: In a polar solvent, use compound IM-1 and compound R1: And its benzene ring side chain alkyl substituted derivatives: The reaction was carried out under the action of catalyst 2 to obtain synthetic compound IM-2; In a polar solvent, compound IM-2 is reacted with R2COCl, wherein R2 is By adjusting the feed ratio of compound IM-2 and R2COCl, modified cellulose is obtained by the reaction; 3. The method for preparing modified cellulose according to claim 2, characterized in that: The catalyst 2 is selected from: potassium carbonate / sodium, potassium hydroxide / sodium, potassium tert-butoxide / sodium, or a combination thereof; The polar solvent is selected from the group consisting of dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, N-methylmorpholine, or a combination thereof; The molar ratio of IM-2 to R2COCl is 1:2-4, and after the reaction, a modified cellulose A having a structural formula A is obtained; The molar ratio of IM-2 to R2COCl is 1:0.5-1.2, and modified cellulose B having structural formula B is obtained after the reaction.

4. A cellulose derivative compound, characterized in that The structural formula is: Wherein, R1 is selected from the following group: a substituted or unsubstituted C12-C24 heteroaryl group, wherein the heteroaryl group has at least two six-membered ring structures; n is 10 to 200; the heteroaryl group includes carbazole, diphenylamine, triphenylamine, diphenyl sulfone, diphenyl sulfoxide, triphenylphosphine, 1,10-phenanthroline, 4-trifluoromethylbenzene and side chain alkyl substituted derivatives thereof.

5. A method for preparing the cellulose derivative compound according to claim 4, characterized in that: The following steps are involved: The compound IM-1 is obtained by reacting cellulose of formula C with N-bromosuccinimide in a polar solvent under the action of catalyst 1; The catalyst 1 is selected from: triphenylphosphine, diphenylphosphine oxide, lithium chloride, lithium bromide, or a combination thereof; In a polar solvent, compound IM-1 is reacted with R1 under the action of the catalyst 2 to obtain; 6. An application of the modified cellulose according to claim 1, characterized in that: Used to prepare the interconnection layer of double-terminal stacked solar cells or as the interconnection layer material.

7. A double-terminal stacked solar cell, characterized in that: The structure includes two sub-batteries and an interconnection layer; the interconnection layer is prepared from the modified cellulose according to claim 1; or is prepared using the modified cellulose as one of the materials.

8. The double-terminal tandem solar cell according to claim 7, characterized in that: The interconnected layer is a single-layer single-component structure prepared from the modified cellulose according to claim 1; its thickness is 5-15 nm.

9. A method for preparing the double-terminal tandem solar cell according to claim 8, characterized in that: The interconnection layer is obtained by spin coating the modified cellulose according to claim 1 on the electron transport layer of the sub-battery using a solution processing process.

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