CN106129255B - Organic solar batteries and preparation method based on extra small period silver nanometer column array - Google Patents

Abstract

The invention relates to the field of solar cells, in particular to the field of organic solar cells. An organic solar cell based on an ultra-small period silver nanocolumn array, the active layer has a groove array corresponding to the silver nanocolumn array, and a silver nanocolumn is inserted in each groove, the smallest unit of the silver nanocolumn array It is an equilateral triangle, the diameter of the nanopillars in the minimum unit of the silver nanopillar array is 12 nm, the height is 35 nm, and the distance between adjacent silver nanopillars is 12 nm. The invention greatly enhances the light absorption capacity of the ultra-thin active layer in the organic solar cell in the wavelength range of 350 nm-850 nm by using the silver nano-cylindrical array with an ultra-small period, and simultaneously obtains the high-efficiency light absorption characteristics of a wide angle.

Description

Organic solar cell and preparation method based on ultra-small period silver nanocolumn array

technical field

The invention relates to the field of solar cells, in particular to the field of organic solar cells.

Background technique

The research and development of organic solar cells (OSCs) is of great significance for the large-scale utilization of solar energy to provide cheap electricity. At present, the biggest problem of OSCs is the low photoelectric conversion efficiency, which does not meet the needs of commercial applications. A very direct solution to improve the photoelectric conversion efficiency of organic solar cells is to improve the light absorption efficiency of the cells. Using a sufficiently thick active layer can ensure the light absorption of the cell, but this is not conducive to the transport and effective collection of carriers. The use of light-harvesting structures, such as nano-patterned metal electrodes, can solve this contradiction, that is, the surface plasmon resonance excited by metal nanostructures can be used to improve the light absorption of the ultra-thin active layer, which meets the optical thickness of the active layer in organic solar cells. Electrically thin requirements to realize high-efficiency organic solar cells. For example, in 2010, Sefunc et al. designed a one-dimensional silver grating with a period of 130nm as the back cathode of a positive solar cell, which increased the light absorption efficiency of the active layer by 21%【Optics Express, 2011, 19(15) 14203】 ; In 2012, Li et al. used a one-dimensional silver grating with a period of 750 nm as the anode of an inverted solar cell, which increased the photocurrent of the cell by 8.27% [J. Phys. Chem. C2012, 116, 7200]; principle However, due to the asymmetry of its structure, the light absorption of the cell depends on the incident angle of light and the polarization of light, which limits its application in the field of solar cells [Advancedmaterials, 2013, 25(17), 2385]. The two-dimensional metal nano-array structure can overcome these shortcomings of the one-dimensional metal nano-grating, and then achieve a better light-harvesting effect. In 2014, Le et al. designed a square array with a period of 400 nm on a silver substrate. The silver nanocylindrical array structure is embedded in an ultra-thin organic polymer film. When the incident light is directly incident on the organic polymer film, its light absorption efficiency increases by 40% under AM1.5 sunlight [IEEE Journal of Photovoltaics IEEE, 2014, 4( 6), 1566]; In 2013, Li et al. used a square-arranged silver nanocylindrical array with a period of 350 nm as the anode of an inverted solar cell, which increased the photocurrent of the cell by 18.1%. [Applied Physics Letters, 2013, 102, 153304]; Ln et al. designed a square-arranged elliptical silver nanoarray with a period of 230 nm as the back cathode of a positive solar cell, making the photocurrent of a solar cell with an ultra-thin active layer An increase of nearly 30% [ACS Photonics 2015, 2, 78−85]. Although these two-dimensional periodic metal nanoarrays with sub-wavelength scale have significantly improved the light harvesting ability of ultra-thin organic solar cells, the improvement is far from meeting the photoelectric conversion efficiency of organic solar cells for commercial applications. Therefore, it is very necessary to explore a better two-dimensional nano-patterned metal electrode structure to promote a greater improvement in the light absorption efficiency of organic solar cells in a wide-spectrum and wide-angle range.

Contents of the invention

The technical problem to be solved by the invention is: how to better improve the light-harvesting ability of the ultra-thin organic solar cell and realize the wide-angle and high-efficiency light-absorbing performance.

The technical scheme adopted in the present invention is:

An organic solar cell based on an ultra-small-period silver nanocolumn array, which consists of sequentially arranged indium tin oxide layers with a thickness of 100 nm as the anode of the cell, and poly(3,4-ethylenedioxide) with a thickness of 20 nm-30 nm. Thiophene)-polystyrene sulfonic acid film as the anode buffer layer, a uniform mixture film of conductive polymer donor material and fullerene derivative acceptor material with a thickness of 40 nm-90 nm as the active layer, and a silver nanometer film with a thickness of 235 nm The pillar array layer is used as the cathode of the battery. The silver nanopillar array layer is composed of a silver film with a thickness of 200 nm and a silver nanopillar array with a height of 35 nm integrated with the silver film. The minimum unit of the silver nanopillar array is positive Triangular, the diameter of the nanocolumn in the minimized unit of the silver nanocolumn array is 12 nm, the height is 35 nm, the distance between adjacent silver nanocolumns is 12 nm, and the active layer has a silver nanocolumn corresponding to the silver nanocolumn array. An array of grooves, with a silver nanopillar inserted into each groove.

As a preferred method: the indium tin oxide is prepared by magnetron sputtering.

As a preferred method: the conductive polymer donor material is poly[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3 -Benzothiadiazole-4,7-diyl-2,5-thiophenediyl, poly[2,7-(5,5-di-(3,7-dimethyloctyl)-5H-di Thieno3,2-b:2′,3′-d]pyran)-4,7-(5,6-difluoro-2,1,3-benzothiadiazole), poly(4,4 '-bis(2-ethylhexyl)dithieno(3,2-b;2',3'-d)silacyclopentadiene)-2,6-diyl-(2,1,3- benzothiadiazole)-4, 7-diyl, and the acceptor material of the fullerene derivative is [6,6]-phenyl C ₇₁ -butyric acid methyl ester.

The method for preparing an organic solar cell based on an ultra-small period silver nanocolumn array is carried out according to the following steps:

Step 1. On the glass substrate, a uniform indium tin oxide film with a thickness of 100 nm is deposited as the anode of the battery by magnetron sputtering;

Step 2, depositing a layer of poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid film with a thickness of 20 nm-30 nm on the indium tin oxide film by solution spin coating as an anode buffer layer;

Step 3. On the poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid film, deposit a layer of conductive polymer donor material and fullerene-derived The homogeneous mixture film of the acceptor material is used as the active layer, and the mass ratio of the conductive polymer donor material to the fullerene derivative acceptor material is 1:1.5;

Step 4. Prepare the nanopillar array stamp. The minimum unit of the nanopillar array stamp is an equilateral triangle, the diameter of the nanopillar in the minimum unit is 12 nm, the height is 35 nm, and the distance between adjacent nanopillars is equal to 12 nm, and then use the nano-column array stamp to imprint the active layer prepared in step 3 to form a groove array on the active layer;

Step 5. On the active layer embossed in step 4, a silver film is plated by vacuum coating technology, so that the thickness of the silver film after filling the grooves with silver is 200 nanometers.

In the ultra-small period silver nanocolumn array, the ultrasmall period means that the length of the projection of the smallest unit of the silver nanocolumn array on any plane in any direction is less than 100 nm.

The beneficial effects of the present invention are: the present invention greatly enhances the light absorption capacity of the ultra-thin active layer in the organic solar cell in the wavelength range of 350 nm-850 nm by using the ultra-small periodic silver nano-cylindrical array, and simultaneously obtains a wide-angle Efficient light absorption properties. When the silver nanocylindrical array adopts a triangular arrangement, the thickness of the active layer is 40nm, the diameter of the silver nanocylindrical is 12nm, the height is 35nm, and the duty ratio is 0.5 (that is, the period is 24nm), under the solar spectrum AM1.5G, the light At normal incidence, the total absorption efficiency reaches 66.8% in the wavelength range of 350nm~850nm, which is 88% higher than that of flat-panel devices with equal volume active layers and no silver nanopillars. The light absorption efficiency of the active layer with a thickness of 62 nm in the flat cell significantly saves the material of the active layer and reduces the production cost of the cell. Reducing the recombination probability of carriers is also conducive to improving the internal quantum efficiency of the battery. When the light incident angle increases from 0° to 70°, the light absorption efficiency can still be maintained at the level of 62.4%. In a word, the silver nanocolumn structure proposed by the present invention greatly enhances the light absorption efficiency of the ultra-thin active layer, and realizes wide-angle high light absorption performance, which is superior to the prior art in terms of performance.

Description of drawings

Figure 1 is a schematic cross-sectional view of a flat organic solar cell structure. As a reference cell structure, codes 101-104 represent anode, anode buffer layer, active layer, and cathode in sequence.

Figure 2 is a three-dimensional schematic diagram of an ultra-thin organic solar cell based on an ultra-small periodic silver nanocolumn array proposed by the present invention. The codes 201-205 represent ITO anode, anode buffer layer, active layer, silver nanocolumn, and silver film in sequence.

Fig. 3 is the schematic diagram of the silver nano-column array with triangular arrangement proposed by the present invention, codes 301-304 respectively represent the diameter of the silver nano-column, the distance between adjacent silver nano-columns, the period of the silver nano-column in the horizontal direction, the silver nano-column The period of the nanopillars in the vertical direction.

Fig. 4 is the graph of the relationship between the absorption efficiency of the active layer and the silver nanocolumn array parameter silver column height and the duty ratio of the triangular arrangement, the abscissa indicates the height of the silver nanocolumn, denoted by h, and the ordinate indicates the duty cycle of the silver nanocolumn Ratio, expressed by f, the absorption efficiency is expressed by the depth of the color, quantitatively see the color bar in the upper right corner of the figure, the parameters of the optimized silver nano cylinder are: the height of the silver nano cylinder is h=35nm, and the duty cycle f=0.5 , the diameter is D = 12nm, and the corresponding point is represented by code 401.

Figure 5 is a comparison of the light absorption spectrum of the active layer in the silver nanocylindrical ultra-thin organic solar cell with an optimized triangular arrangement proposed by the present invention (the thickness of the active layer is 40nm) and the equivalent flat structure solar cell with an equal-volume active layer In the figure, corresponding to codes 501 and 502 respectively, the abscissa is the wavelength of the incident light, represented by λ ₀ , and the unit is nm, and the ordinate represents the absorption efficiency, represented by ƞ.

Fig. 6 is the improved spectrogram of light absorption efficiency compared with the equivalent flat plate structure active layer of the silver nanocylindrical ultra-thin organic solar cell with optimized triangular arrangement proposed by the present invention, by code 601 curve express. The abscissa is the wavelength of the incident light, represented by _λ0 , and the unit is nm, and the ordinate is the light absorption efficiency improvement factor, represented by Δƞ.

Fig. 7 is a comparison of the total light absorption efficiency of the triangular-arranged silver nanocylindrical organic solar cells proposed by the present invention and the equivalent planar structure cell with the change curve of the active layer thickness, represented by codes 701 and 702 respectively. The abscissa is the thickness of the active layer of the silver nanocylindrical organic solar cell with a triangular arrangement, represented by t, and the unit is nm, and the ordinate is the total light absorption efficiency (that is, the integral of the light absorption efficiency in the wavelength range of 350 nm-850 nm ), denoted by ƞ _A. It is pointed out that when the thickness of the active layer varies in the range of 40 nm-120 nm, the total light absorption efficiency of the silver nanocylindrical organic solar cells with triangular arrangement is always better than that of the equivalent planar structure cells. (Here the parameters of the silver nanocolumns remain unchanged: the height of the silver nanocolumns is 35nm, and the diameter is 12nm when the duty cycle is 0.5.)

Fig. 8 is a curve diagram of the total light absorption efficiency of the active layer of the silver nano-cylindrical ultra-thin organic solar cell with triangular arrangement of the present invention as a function of the incident angle of light. , and the ordinate is the total light absorption efficiency, represented by ƞ _A. (The parameters of the silver nano cylinder in the battery here are: the height of the silver nano cylinder is 35nm, the diameter is 12nm when the duty ratio is 0.5, and the thickness of the active layer is 40nm).

Fig. 9 is a comparison diagram of the absorption spectrum of the active layer of the silver nano-cylindrical ultra-thin organic solar cell with a triangular arrangement and the active layer of the silver nano-cylindrical ultra-thin organic solar cell with a square arrangement, and the abscissa is the wavelength of the incident light , represented by λ ₀ , the unit is nm, and the ordinate represents the absorption efficiency, represented by ƞ. 901 represents the absorption spectrum of the active layer of the ultra-thin organic solar cell with silver nano cylinders arranged in a triangle, and 902 represents the absorption spectrum of the active layer of the ultra-thin organic solar cell with silver nano cylinders arranged in a square.

Detailed ways

Example 1

Step 1. On the glass substrate, a uniform indium tin oxide (ITO) film with a thickness of 100nm is deposited by magnetron sputtering as the anode of the battery;

Step 2. Deposit a layer of poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT:PSS) film with a thickness of 20 nm on the indium tin oxide film by solution spin coating as an anode buffer layer ; Preparation conditions: spin coating rate 3000 rpm, spin coating time 45 s, and then annealed at 120 °C for 10 min in air.

Step 3. On the poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid film, a layer of conductive polymer donor material (PSBTBT) and fullerene derivatives was deposited with a thickness of 40 nm by solution spin coating. The homogeneous mixture film of the material acceptor material (PC ₇₁ BM) is used as the active layer, and the mass ratio of the conductive polymer donor material to the fullerene derivative acceptor material is 1:1.5; PSBTBT is poly(4, 4'-bis( 2-Ethylhexyl)dithieno(3,2-b; 2',3'-d)silacyclopentadiene)-2,6-diyl-(2,1,3-benzothienodi azole)-4,7-diyl, PC ₇₁ BM is [6,6]-phenyl C ₇₁ -butyric acid methyl ester. Dissolve PSBTBT and PC ₇₁ BM in chlorobenzene solution at a concentration of 20 mg/mL (the sum concentration of PSBTBT and PC ₇₁ BM), and then spin-coat at a spin-coating rate of 1000 rpm for 60 s to obtain a uniform layer thickness PSBTBT:PC ₇₁ BM film

Step 4. Prepare the nanopillar array stamp. The minimum unit of the nanopillar array stamp is an equilateral triangle, the diameter of the nanopillar in the minimum unit is 12 nm, the height is 35 nm, and the distance between adjacent nanopillars is equal to 12 nm, and then use the nano-column array stamp to imprint the active layer prepared in step 3 to form a groove array on the active layer; 2033-05; J. Vac. Sci. Technol. B22(4), 2004], prepared by combining plasma-enhanced chemical vapor deposition, selective etching, and electron beam etching. Firstly, plasma-enhanced chemical vapor deposition, selective The one-dimensional periodic strip/groove structure is prepared by etching technology, and then the nano-column array arranged in a triangle is further constructed on the template of the one-dimensional periodic strip/groove structure by electron beam etching technology. Compared with the single use of electron beam etching technology, it can save costs, and according to the literature [Acta Physica Sinica, 2006, 55 (4)], the one-dimensional periodic strip/ The quality of the groove structure is better than that of the template prepared by electron beam etching technology.

Step 5. On the active layer embossed in step 4, a silver film is plated by vacuum coating technology, so that the thickness of the silver film after filling the groove with silver is 200 nm. The vacuum degree is maintained at 10 ^-4 -10 ^-5Pa , and the deposition rate is maintained at 0.5 nm/s.

Example 2

Step 1. On the glass substrate, a uniform indium tin oxide (ITO) film with a thickness of 100nm is deposited by magnetron sputtering as the anode of the battery;

Step 2. Deposit a layer of poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT:PSS) film with a thickness of 20 nm on the indium tin oxide film by solution spin coating as an anode buffer layer ; Preparation conditions: spin-coating rate 3000rpm, spin-coating time 45 s, and then annealed at 120 ℃ for 10 min in air. In order to better improve the photoelectric conversion efficiency, poly(3,4-ethylenedioxythiophene) The foaming agent sodium bicarbonate is added to the styrene sulfonic acid (PEDOT:PSS) solution, so that the mass percent concentration of sodium bicarbonate is 0.5-1%, and bubbles are generated during the annealing process to enhance the light absorption efficiency.

Step 3. On the poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid film, a layer of conductive polymer donor material (PSBTBT) and fullerene derivatives was deposited with a thickness of 40 nm by solution spin coating. The homogeneous mixture film of material acceptor material (PC ₇₁ BM) is used as the active layer, and the mass ratio of conductive polymer donor material to fullerene derivative acceptor material is 1:1.5; PSBTBT is PSBTBT is poly(4, 4'- Bis(2-ethylhexyl)dithieno(3,2-b; 2',3'-d)silacyclopentadiene)-2,6-diyl-(2,1,3-benzo Thiadiazole)-4,7-diyl, PC ₇₁ BM is [6,6]-phenyl C ₇₁ -butyric acid methyl ester. Dissolve PSBTBT and PC ₇₁ BM in chlorobenzene solution at a concentration of 20 mg/mL (the sum concentration of PSBTBT and PC ₇₁ BM), and then spin-coat at a spin-coating rate of 1000 rpm for 60 s to obtain a layer with uniform thickness PSBTBT: PC ₇₁ BM film;

Step 4. Prepare the nanopillar array stamp. The minimum unit of the nanopillar array stamp is an equilateral triangle, the diameter of the nanopillar in the minimum unit is 12 nm, the height is 35 nm, and the distance between adjacent nanopillars is equal to 12 nm, and then use the nano-column array stamp to imprint the active layer prepared in step 3 to form a groove array on the active layer; 2033-05; J. Vac. Sci. Technol. B22(4), 2004], prepared by combining plasma-enhanced chemical vapor deposition, selective etching, and electron beam etching. Firstly, plasma-enhanced chemical vapor deposition, selective The one-dimensional periodic strip/groove structure is prepared by etching technology, and then the nano-column array arranged in a triangle is further constructed on the template of the one-dimensional periodic strip/groove structure by electron beam etching technology. Compared with the single use of electron beam etching technology, it can save costs, and according to the literature [Acta Physica Sinica, 2006, 55 (4)], the one-dimensional periodic strip/ The quality of the groove structure is better than that of the template prepared by electron beam etching technology.

Step 5. On the active layer embossed in step 4, a silver film is plated by vacuum coating technology, so that the thickness of the silver film after filling the groove with silver is 200 nm. The vacuum degree is maintained at 10 ^-4 -10 ^-5Pa , and the deposition rate is maintained at 0.5 nm/s.

Claims (5)

1. a kind of organic solar batteries based on extra small period silver nanometer column array, it is characterised in that：By tactic thickness Poly- (the 3,4- ethylene dioxy thiophenes that anode of the indium tin oxide layer as battery, the thickness that degree is 100nm are 20 nm-30 nm Pheno)-polystyrolsulfon acid film as anode buffer layer, thickness be 40 nm-90nm conducting polymer donor material and fowler Ene derivative acceptor material homogeneous mixture film as active layer, thickness be 235nm silver nanometer column array layer as battery Cathode, silver nanometer column array layer integrally changes the silver that structure height is 35 nm by the silverskin that thickness is 200 nm and with silverskin Nano column array forms, and the minimum unit of silver nanometer column array is equilateral triangle, in the minimum unit of silver nanometer column array A diameter of 12 nm of nano-pillar is highly 35 nm, and the distance between adjacent silver nanometer column is 12 nm, is had on active layer There is groove array corresponding with silver nanometer column array, a silver nanometer column is inserted into each groove.

2. a kind of organic solar batteries based on extra small period silver nanometer column array according to claim 1, feature It is：Indium tin oxide is prepared using the method for magnetron sputtering.

3. a kind of organic solar batteries based on extra small period silver nanometer column array according to claim 1, feature It is：Conducting polymer donor material is poly- [9- (1- octyls nonyl) -9H- carbazole -2,7- diyls] -2,5- thiophene diyl -2, 1,3- diazosulfide -4,7- diyl -2,5- thiophene diyl, poly- [2,7- (two thiophenes of 5,5- bis--(3,7- dimethyl octyl) -5H- Pheno and 3,2-b:2 ', 3 '-d] pyrans) -4,7- (bis- fluoro- 2,1,3- diazosulfides of 5,6-), poly- ((the 2- ethyls of 4,4'- bis- Hexyl) dithieno (3,2-b;2', 3'-d) Silole) -2,6- diyls (2,1,3- diazosulfides) -4, Any one in 7- diyls, fullerene derivative receptor material is [6,6]-phenyl C₇₁Methyl butyrate.

4. the method for preparing the organic solar batteries based on extra small period silver nanometer column array described in claim 1, feature It is to carry out according to following step：

Step 1: on a glass substrate, depositing the uniform indium tin that a layer thickness is 100nm by the method for magnetron sputtering and aoxidizing Anode of the object film as battery；

Step 2: depositing the poly- (3,4- that a layer thickness is 20 nm-30 nm by solution spin-coating method on indium and tin oxide film Ethene dioxythiophene)-polystyrolsulfon acid film is as anode buffer layer；

Step 3: depositing a thickness by solution spin-coating method on poly- (3,4- ethene dioxythiophenes)-polystyrolsulfon acid film The conducting polymer donor material and fullerene derivative receptor material homogeneous mixture film conduct that degree is 40 nm-, 90 nm The mass ratio of active layer, conducting polymer donor material and fullerene derivative receptor material is 1:1.5；

Step 4: preparing nano column array type seal, the minimum unit of nano column array type seal is equilateral triangle, is minimized A diameter of 12 nm of nano-pillar in unit, is highly 35 nm, the distance between adjacent nano-pillar is 12 nm, is then made The active layer prepared to step 3 with nano column array type seal imprints, and groove array is formed on active layer；

Step 5: on the active layer by step 4 coining, silverskin is plated using vacuum coating technology, after making the full groove of silver filling Silver film thickness be 200 nm.

5. organic sun based on extra small period silver nanometer column array described in preparation claim 1 according to claim 4 The method of energy battery, it is characterised in that：Conducting polymer donor material is poly- [9- (1- octyls nonyl) -9H- carbazoles -2,7- two Base] -2,5- thiophene diyl -2,1,3- diazosulfide -4,7- diyl -2,5- thiophene diyl, poly- [2,7- (5,5- bis--(3,7- Dimethyl octyl) -5H- dithienos 3,2-b:2 ', 3 '-d] pyrans) -4,7- (bis- fluoro- 2,1,3- benzos thiophenes two of 5,6- Azoles), poly- (4,4'- bis- (2- ethylhexyls) dithieno (3,2-b; 2', 3'-d）Silole）- 2,6- diyls- (2,1,3- diazosulfides）Any one in -4,7- diyl, fullerene derivative receptor material is [6,6]-phenyl C₇₁- Methyl butyrate.