CN103346259B - A kind of organic solar batteries - Google Patents

Abstract

The invention discloses an organic solar cell, comprising: an anode for collecting holes; a cathode for collecting electrons; a photoactive layer for generating hole-electron pairs, interposed between the anode and the cathode; an electron transport layer intervening Between the cathode and the photoactive layer; wherein, the electron transport layer is an organic small molecule layer, and the organic small molecule layer is doped with a luminescent material, which does not absorb light or has low light absorption efficiency for the photoactive layer wavelength band, the luminescent material absorbs energy in this band, and emits a light band that is easily absorbed by the photoactive layer, thereby improving the light absorption efficiency of the photoactive layer and effectively improving the photoelectric conversion efficiency of the solar cell.

Description

An organic solar cell

technical field

The invention belongs to the field of solar cells, and in particular relates to an organic solar cell.

Background technique

The development of the times requires a large amount of energy, and fossil energy, as a direct primary energy source, has been used in large quantities and is increasingly depleted, which has become a bottleneck restricting development. As a continuous source of clean energy, solar energy has attracted more and more attention. Among them, making high-efficiency solar cells to convert solar energy into electrical energy has become an important method for utilizing solar energy. Solar cells are mainly divided into inorganic solar cells (mainly made of silicon-based or other inorganic material substrates) and organic solar cells. Organic solar cells are increasingly valued due to their advantages such as easy availability of materials, low cost, easy large-scale production, and flexibility. , so it has gradually become a very promising new type of solar cell.

The structure of organic solar cells includes: anode, hole transport layer, photoactive layer, electron transport layer and cathode. Its working principle is mainly to use organic matter with photosensitive properties as the material of photoactive layer. Sunlight enters the photoactive layer through the transparent anode, and the organic matter in the photoactive layer is excited after absorbing sunlight, thereby generating electron-hole pairs, that is, excitons (or called carriers), and the electrons and The holes are dissociated into the electron transport layer and the hole transport layer respectively, and are finally transported to the cathode and anode, thereby generating photoelectric current. The whole process can also be called photovoltaic effect.

As we all know, compared with silicon-based inorganic solar cells, the photoelectric conversion efficiency of organic solar cells is still lower. Therefore, improving the photoelectric conversion efficiency is the core technical problem that needs to be solved for the industrialization of organic solar cells. However, due to the limitation of the forbidden band width of organic substances in the photoactive layer of organic solar cells, it is impossible for organic substances to fully respond to the spectrum of all bands, that is, the light bands with lower energy in the solar spectrum cannot excite the photoactive layer. organic matter to generate excitons, which also leads to the limitation of organic solar cells for the absorption of sunlight. Therefore, without affecting other performances, improving the light absorption efficiency of the photoactive layer becomes an effective way to improve organic solar cells. important means. At present, there have been some disclosures of various technologies on improving the light absorption efficiency of the photoactive layer, such as improving the light absorption efficiency by optimizing and improving the specific selection of materials for the organic matter of the photoactive layer. Another example is the applicant's previous patent application, whose publication number is CN102751439A, which discloses an organic solar cell, through which metal nanoparticles are provided in the electron transport layer and/or hole transport layer, and the metal nanoparticles The surface plasmon effect of the photoactive layer enhances the absorption of light, which increases the photocurrent of the solar cell, thereby significantly improving the photoelectric conversion efficiency of the organic solar cell device.

The above methods have effectively improved the light absorption efficiency of organic solar cells to a certain extent, but it is still not enough to effectively realize the industrialization requirements of organic solar cells. How to further improve the light absorption efficiency of the photoactive layer is still a problem. An important technical proposition that urgently needs to be continuously studied.

Contents of the invention

In view of this, based on years of research experience and accumulated expertise in organic solar cells, the applicant proposes the application of the present invention after a large number of experiments and verifications. The purpose of the present invention is to propose an organic solar cell that can effectively improve The light absorption efficiency of the photoactive layer can further improve the photoelectric conversion efficiency of the organic solar cell and accelerate the industrialization process of the organic solar cell.

A kind of organic solar cell proposed according to the object of the present invention, wherein, comprises:

an anode that collects holes;

a cathode that collects electrons;

a photoactive layer generating hole-electron pairs, between said anode and cathode;

An electron transport layer, between the cathode and the photoactive layer;

Wherein, the electron transport layer is an organic small molecule layer, and the organic small molecule layer is doped with a luminescent material, and for a wavelength band that is not absorbed by the photoactive layer or has a low light absorption efficiency, the luminescent material absorbs the energy of the wavelength band , and emit a light band that is easily absorbed by the photoactive layer, thereby improving the light absorption efficiency of the photoactive layer.

Preferably, a hole transport layer is also included, interposed between the anode and the photoactive layer.

Preferably, the luminescent material is selected from Ir(ppy)3, Ir(ppy)2(acac), Ir(mppy)3, Ir(pq)2(acac), Ir(bt)2(acac), Ir (MDQ)2(acac), Ir(pq)3, Ir(flq)2(acac), Ir(fliq)2(acac), Ir(piq)2(acac), Ir(piq)3, Ir(btp ) 2(acac), C545T, DCM, DCJTB, Perylene, DPAVBi, DPAVB, BDAVBi, FirPic or Rubrene or a mixture of several.

Preferably, the small organic molecules in the small organic molecule layer are one or a mixture of Alq3, BCP, BPhen, Liq, BAlq, 3TPYMB, TAZ or TPBi.

In order to save text space, the present invention mainly adopts simplified name labeling for organic molecules, and the specific corresponding name list is shown in the following table 1:

Table 1 Corresponding Name Table

Preferably, the doping concentration of the luminescent material in the organic small molecule layer is equal to or less than 50%. Further preferably, the doping concentration of the luminescent material in the organic small molecule layer can be selected to be 1-10%.

Preferably, the thickness of the electron transport layer is in the range of 1-200nm.

In traditional organic solar cells, a transparent conductive oxide (TCO; Transparent Conducting Oxide) coating layer is generally made on a glass or plastic substrate, and the glass or plastic substrate coated with TCO is used as the anode substrate of the battery, and then on the anode A hole collection layer is formed on the substrate. The material of the hole collection layer is generally made of conductive polymers such as poly 3,4-ethylenedioxythiophene: poly 4-toluene sulfonic acid (PEDOT: PSS), but in practical applications it is found that , The material in the hole collection layer will corrode the TCO coating layer of the anode, which seriously affects the service life of the organic solar cell.

In order to solve the above technical problems, preferably, the solar cell of the present invention is an inverted structure, and the inverted structure means that the cathode is used as a sunlight receiving surface, and sunlight enters the photoactive layer through the cathode; further Preferably, the cathode is formed on the substrate, and its material is TCO of transparent material or TCO containing dopant, and the material of the anode is metal.

Preferably, the hole collection layer may be a transition metal oxide or a conductive polymer.

Preferably, a buffer layer for adjusting the intensity distribution of light in each layer is further included, and the buffer layer is adjacent to the cathode or the anode.

Preferably, the fabrication method of the electron transport layer is selected from co-evaporation, solution spin coating, spray coating, screen printing, inkjet printing, chemical synthesis, electron beam deposition or self-assembly.

Of course, the present invention can combine the applicant's previous optimization technical solutions and other prior related technical solutions to further improve the photoelectric conversion efficiency of the organic solar cell described in the present invention, that is, the implementation effect will be better. It is believed that these combinations They all belong to the routine choices of those skilled in the art, and also belong to the scope of protection of the claims of the present invention, and will not be described in detail here.

In the organic solar cell provided by the present invention, since its electron transport layer is a mixed layer composed of luminescent materials and organic small molecules in a certain proportion, the luminescent material absorbs the wavelength bands that are not absorbed by the photoactive layer or have low light absorption efficiency. energy, and emit a light band that is easily absorbed by the organic matter in the photoactive layer, which indirectly expands the solar spectrum absorption band range of the organic matter in the photoactive layer, thereby improving the light absorption efficiency of the photoactive layer and effectively improving the photoelectric conversion efficiency of the solar cell; further Specifically, the present invention sets the solar cell into an inverted structure, that is, the cathode is used as a sunlight receiving surface, and sunlight enters the photoactive layer through the cathode, and the cathode is formed on the substrate. When the material is preferably TCO of transparent material or TCO containing dopant, when the anode material is a metal, since the electron transport layer of the present invention is a neutral organic small molecule layer, it will not corrode the TCO material of the cathode, meeting Under the premise of the same performance, it also effectively avoids the corrosion of the TCO film layer of the anode caused by the material of the hole collection layer in the existing non-inverted organic solar cell, and greatly prolongs the service life of the solar cell.

Description of drawings

Accompanying drawing 1 is the structural distribution diagram of the first embodiment of the organic solar cell of the present invention;

Accompanying drawing 2 is the structural distribution diagram of the fourth embodiment of the organic solar cell of the present invention;

Accompanying drawing 3 is the structural distribution diagram of the fifth embodiment of the organic solar cell of the present invention;

Accompanying drawing 4 is the structural distribution diagram of the sixth embodiment of the organic solar cell of the present invention;

Accompanying drawing 5 is the structural distribution diagram of the seventh embodiment of the organic solar cell of the present invention;

Accompanying drawing 6 is the sequential block diagram of the manufacturing steps of the first embodiment of the organic solar cell of the present invention;

Accompanying drawing 7 is the sequential block diagram of the manufacturing steps of the fourth embodiment of the organic solar cell of the present invention;

Accompanying drawing 8 is the sequential block diagram of the fabrication steps of the fifth embodiment of the organic solar cell of the present invention;

Accompanying drawing 9 is the sequential block diagram of the fabrication steps of the sixth embodiment of the organic solar cell of the present invention;

Accompanying drawing 10 is the sequential block diagram of the fabrication steps of the seventh embodiment of the organic solar cell of the present invention;

Accompanying drawing 11 is the comparison diagram of the current-voltage curve obtained under the irradiation condition of 100W/cm ² of the organic solar cell of the first to the third embodiment of the present invention and the prior art;

Accompanying drawing 12 is the graph comparing the external quantum efficiency curve obtained under the condition of 100W/cm ² of the organic solar cell of the first to the third embodiment of the present invention and the prior art.

detailed description

The embodiment of the present invention discloses an organic solar cell, which includes:

an anode that collects holes;

a cathode that collects electrons;

a photoactive layer generating hole-electron pairs, between said anode and cathode;

An electron transport layer, between the cathode and the photoactive layer;

A hole transport layer, between the anode and the photoactive layer;

Wherein, the electron transport layer is an organic small molecule layer, and the organic small molecule layer is doped with a luminescent material, and for a wavelength band that is not absorbed by the photoactive layer or has a low light absorption efficiency, the luminescent material absorbs the energy of the wavelength band , and emit a light band that is easily absorbed by the photoactive layer, thereby improving the light absorption efficiency of the photoactive layer;

The luminescent material is selected from Ir(ppy)3, Ir(ppy)2(acac), Ir(mppy)3, Ir(pq)2(acac), Ir(bt)2(acac), Ir(MDQ) 2(acac), Ir(pq)3, Ir(flq)2(acac), Ir(fliq)2(acac), Ir(piq)2(acac), Ir(piq)3, Ir(btp)2( acac), C545T, DCM, DCJTB, Perylene, DPAVBi, DPAVB, BDAVBi, FirPic or a mixture of Rubrene, of course other equivalent materials can also be used;

The organic small molecules in the organic small molecule layer are one or a mixture of Alq3, BCP, BPhen, Liq, BAlq, 3TPYMB, TAZ or TPBi, and of course other equivalent materials can also be used.

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some preferred embodiments of the present invention. Those skilled in the art can also obtain other drawings and embodiments according to these drawings and embodiments without creative work.

First embodiment mode

Referring to FIG. 1 , FIG. 1 is a schematic diagram of the structure distribution of the first embodiment of the organic solar cell of the present invention. As shown in FIG. 1 , the organic solar cell 10 is an inverted structure, specifically including a substrate 11 , and the material of the substrate 11 can be hard, such as glass or quartz, or flexible, such as flexible polymer. Polymer materials that can be used as flexible substrates include (but are not limited to): polyethylene naphthalate (PEN; polyethylenenaphthalate), polyethylene terephthalate (PET; polyethyleneterephthalate), polyamide (polyamide), polyester Polymethylmethacrylate, Polycarbonate, or polyurethane. Flexible substrates can be used in continuous processes, such as web-coating or lamination processes. In addition, in addition to insulating materials, the substrate may also be made of conductive materials, such as titanium, aluminum, copper, nickel and other metal materials. The thickness of the substrate is not particularly limited, and can be properly adjusted according to actual needs.

A cathode 12 is provided on the surface of the substrate 11, and the cathode 12 is used as a sunlight receiving surface and is made of a transparent material. The specific material can be TCO or metal (such as translucent Au), so that sunlight can reach the photoactive layer 13 through the cathode 12. Preferred cathode 12 materials are TCO or TCO containing doped (doped), including (but not limited to): tin oxide, fluorine-doped tin oxide, indium tin oxide (ITO; indiumtinoxide) and/or azo oxide (AZO ) etc.; the cathode 12 can be formed on the substrate 11 by any conventional method, such as vapor deposition, sputtering, evaporation, etc.

An organic small molecule layer doped with a luminescent material is formed on the cathode 12, which is the electron transport layer 13, wherein the luminescent material is C545T, and the organic small molecule in the organic small molecule layer is Alq3, wherein the C545T The doping concentration is 3%; the thickness range of the electron transport layer is 1-200nm, and the specific thickness can be selected according to actual needs.

The fabrication method of the electron transport layer 13 is selected from co-evaporation, solution spin coating, spray coating, screen printing, inkjet printing, chemical synthesis, electron beam deposition or self-assembly, or obtained by other equivalent methods, wherein , solution spin coating is the preferred manufacturing method, which not only has the advantages of saving energy and resources, but also is simple to operate.

A photoactive layer 14 is formed on the electron transport layer 13, and the photoactive layer 14 includes a donor material and an acceptor material. The donor material and the acceptor material can be a bulk heterojunction layer structure formed by mixing, or It can be a double-layer heterojunction layer structure formed by film formation; preferably, the donor material is a conjugated polymer, and the conjugated polymer includes but is not limited to: poly(3-hexylthiophene ) (P3HT; poly-3-hexylthiophene), polyacetylene (Polyacetylene), polyisobenzothiophene (PITN; polyisothianaphthene), polythiophene (PT; polythiophene), polypyrrole (PPr; polypyrrole); polyfluorene (PF; polyfluorene ), polyphenylene (PPP; poly(p-phenylene)), polyphenylene vinylene (PPV; poly(phenylenevinylene)) derivatives; the donor material can also be a conjugated small organic molecule, such as phthalocyanine Copper (CuPc), subphthalocyanine (SubPc; chloroboronsubphthalocyanine), SubNc (chloroboronsubnaphthalocyanine), copper phthalocyanine (ZnPc), titanium cyanocyanine (OTiPc), pentacene (Pentacene), etc.; the acceptor material Including (but not limited to): poly(cyanophenylene vinylene), fullerenes and their derivatives, organic molecules, organometallics, inorganic nanoparticles, preferably fullerenes and their derivatives, such as PCBM ((6, 6)-Phenyl-C61-butyric acid methylester), PC ₇₀ BM ((6,6)-Phenyl-C71-butyric acid methylester), ICBA (indene-C60bisadduct), IC ₇₀ BA (indene–C70bisadduct), etc.

When making the photoactive layer 14, preferably, the donor material and the acceptor material are mixed in a solvent to obtain a donor-acceptor mixed solution, and then the obtained donor-acceptor mixed solution is deposited by spin coating On the electron transport layer 13 : in addition to spin coating, other commonly used deposition methods include: spray coating, screen printing, inkjet printing, etc., or obtained by other equivalent methods.

A hole transport layer 15 is also formed on the photoactive layer 14, and the hole collection layer 15 can be a transition metal oxide or a conductive polymer. Specifically, preferably, the transition metal oxides include but are not limited to: molybdenum trioxide (MoO ₃ ), tungsten trioxide (WO ₃ ), nickel oxide (NiO) and/or vanadium pentoxide (V ₂ O ₅ ) , can also be other equivalent materials, such as zinc oxide, titanium oxide, etc.; the conductive polymer includes but not limited to: PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(tyrenesulfonate)), or other equivalent known material.

The hole transport layer 15 can be obtained by co-evaporation, solution spin coating, spray coating, screen printing, inkjet printing and other methods, or other equivalent methods.

An anode 16 is formed on the hole transport layer 15, and the material of the anode 16 can be a metal or a conductive oxide, preferably a metal with opaque or low light transmittance, such as aluminum (Al), magnesium (Mg), silver (Ag ), gold (Au), platinum (Pt), copper (Cu), one or more alloys, such as aluminum-magnesium alloy (Mg/Al), silver-magnesium alloy (Ag/Ag), the metals also It can be a layered structure, such as lithium fluoride: aluminum (LiF/Al). The fabrication method of the anode is usually deposition by vapor deposition, but of course other deposition methods can also be used.

Referring to Fig. 6, Fig. 6 is a sequence block diagram of the manufacturing steps of the organic solar cell 10 according to the first embodiment. When each structure selects a specific preferred material: the substrate 11 is made of transparent conductive glass, the cathode 12 is made of transparent ITO film, and the photoactive The donor material of layer 14 is P3HT (poly(3-hexylthiophene)), the acceptor material is PCBM ((6,6)-Phenyl-C61-butyricacidmethylester), the material of hole transport layer 15 is MoO ₃ , and the material of anode 16 is selected Al, in conjunction with specific preferred material selection, specifically illustrate each step shown in Figure 6:

Step 101: Fabricate the cathode 12 on the substrate 11, and its specific fabrication process can be as follows:

A transparent conductive glass is selected as the substrate 11 , and a transparent ITO film is coated on the substrate 11 , and the formed transparent ITO film is used as the cathode 12 .

After the step of coating the transparent ITO thin film on the glass substrate 11 is completed, the substrate coated with the TCO thin film is put into an ultrasonic water bath, and utilize acetone, absolute ethanol and deionized water as solvents to treat the transparent ITO thin film respectively. Ultrasonic cleaning is performed, and the cleaning time can be selected within the range of 20-30 minutes, and then put into a drying oven for drying.

Step 102: Fabricate an electron transport layer 13 on the cathode 12, and its specific fabrication process can be as follows:

Place the ITO substrate obtained in the above step 101 on the suction cup of the spin coater, and spin-coat the ITO substrate with a mixed solution of small organic molecules of C545T with a doping concentration of 3%, wherein the small organic molecules are Alq ₃ , and the spin coating rate is Control in the range of 500-10000r/min, set the spin coating time according to the thickness of the electron transport layer, after the spin coating is completed, thermally anneal the electron transport layer, the annealing temperature is controlled at 50-150 degrees Celsius, or it can be adjusted according to actual needs Setting, the annealing time can be controlled between 5-30 minutes, and can also be set according to actual needs.

Step 103: Fabricate a photoactive layer 14 on the electron transport layer 13, and its specific fabrication process can be as follows:

Put the ITO substrate on which the electron transport layer 13 has been deposited obtained in the above step 102 into a glove box filled with nitrogen, and spin-coat the polymer P3HT:PCBM mixed solution on the electron transport layer 13 . The specific spin-coating speed and spin-coating time can be set according to needs, for example, the spin-coating speed can be 300-10000r/min, the spin-coating time is 10-240sec, and it will evaporate naturally to Drying and volatilization time can be controlled within 20-200min, then heat the ITO substrate to a specified temperature in the glove box (for example, it can be between 100-200 degrees Celsius), and keep the specified temperature for a certain period of time (such as 5-30min ), until the photoactive layer 14 formed by the polymer P3HT: PCBM mixed solution is relatively stable.

Step 104: Fabricate a hole collection layer 15 on the photoactive layer 14, and its specific fabrication process can be as follows:

First, the ITO substrate that has been deposited with the photoactive layer 14 and the electron transport layer 13 obtained in the above step 103 is moved to the vacuum evaporation chamber, and the MoO3 layer is evaporated at a set evaporation rate, and the formed MoO3 layer is used as a hole transport layer. Layer 15.

Step 105: Fabricate the anode 16 on the hole collection layer 15, and its specific fabrication process can be as follows:

An Al thin film with a set thickness is deposited on the hole transport layer 15, and the formed Al thin film serves as the anode 16 of the organic solar cell. The speed of depositing Al can be between 0.1-1 nm/sec, and of course can also be set as required.

Second embodiment mode

The structure of the organic solar cell shown in FIG. 1 can also be referred to. Compared with the first embodiment, the second embodiment differs only in that an organic small molecule layer doped with a luminescent material is formed on the cathode 12, that is, An electron transport layer 13, wherein the luminescent material is C545T, the organic small molecule in the organic small molecule layer is Alq3, the doping concentration of the C545T is 7%, and the rest of the technical solutions are the same as those in the first implementation Example way.

The third embodiment mode

The structure of the organic solar cell shown in FIG. 1 can also be referred to. Compared with the first embodiment, the third embodiment differs only in that an organic small molecule layer doped with a luminescent material is formed on the cathode 12, that is, It is the electron transport layer 13, wherein, the luminescent material is C545T, the organic small molecule in the organic small molecule layer is Alq3, the doping concentration of the C545T is 10%, and the rest of the technical solutions are the same as the first implementation Example way.

This application compares the implementation effect of the embodiment of the present invention with the prior art (based on the four core characteristic parameters of the solar cell - open circuit voltage V _OC , short circuit current density J _SC , fill factor FF photoelectric conversion efficiency n, For specific comparison, see Table 2 below:

Table 2 The implementation effect comparison table of the embodiment mode of the present invention and the prior art

It can be seen from the above table 2 that compared with the electron transport layer without doped luminescent material, the open circuit voltage of the organic solar cells of the first embodiment mode and the second embodiment mode of the present invention is basically unchanged, while the short circuit current density , fill factor, and conversion efficiency are relatively improved compared to the prior art of serial number 1.

From the comparison diagram of the current-voltage curve shown in FIG. 11 and the comparison diagram of the external quantum efficiency curve shown in FIG. 12, it can be seen more intuitively that the photoelectricity of the organic solar cell device of the first embodiment mode and the second embodiment mode of the present invention The current and photoelectric conversion efficiencies have been effectively improved. At the same time, it also shows that after the present invention dopes the luminescent material into the organic small molecule to form the electron transport layer, it also effectively increases the free charge of the electron transport layer, that is, improves the conductivity of the organic solar cell device, and can further improve the organic solar cell. Photoelectric conversion efficiency.

Fourth embodiment mode

Referring to FIG. 2 , FIG. 2 is a schematic diagram of the structure distribution of the fourth embodiment of the organic solar cell of the present invention. 2, the organic solar cell 10 is a non-inverted structure, specifically including a substrate 21, and an anode 22, a hole transport layer 23, a photoactive layer 24, an electron transport layer 25 and a cathode 26 sequentially formed on the substrate 21, Compared with the first embodiment, the fourth embodiment is mainly different in that: the anode 22 is directly formed on the surface of the substrate 21, the anode 22 is used as the sunlight receiving surface, and is made of transparent material, and the cathode 26 is made of opaque metal Materials, and crafting order changes.

Referring to FIG. 7 , which is a sequence block diagram of the fabrication steps of the organic solar cell 10 according to the fourth embodiment, the fabrication sequence includes:

Step 201: making an anode 22 on the substrate 21;

Step 202: forming a hole collection layer 23 on the anode 22;

Step 203: making a photoactive layer 24 on the hole collection layer 23;

Step 204: making an electron transport layer 25 on the photoactive layer 24;

Step 205: making a cathode 26 on the electron transport layer 25;

The remaining specific structures, manufacturing methods and principles can be the same as those in the first, second or third embodiment, and will not be repeated here.

Fifth Embodiment Mode

Referring to FIG. 3 , FIG. 3 is a schematic diagram of the structural distribution of an organic solar cell according to a fifth embodiment of the present invention. 3, the solar cell 10 is an inverted structure, specifically including a substrate 31, and a cathode 32, a buffer layer 37, an electron transport layer 33, a photoactive layer 34, a hole transport layer 35 and an anode sequentially formed on the substrate 31. 36. Compared with the first embodiment, the fifth embodiment is mainly different in that it also includes a buffer layer 37 for adjusting the intensity distribution of light in each layer, and the buffer layer 37 is interposed between the Between the cathode 32 and the electron transport layer 33 , that is, the buffer layer 37 is adjacent to the cathode 32 . Preferably, the material of the buffer layer 37 is transition metal oxide or fluoride.

Referring to FIG. 8 , which is a sequence block diagram showing the fabrication steps of the organic solar cell 10 according to the fifth embodiment, the fabrication sequence includes:

Step 301: making cathode 32 on substrate 31;

Step 302: making a buffer layer 37 on the cathode 32;

Step 303: forming an electron transport layer 33 on the buffer layer 37;

Step 304: making a photoactive layer 34 on the electron transport layer 33;

Step 305: forming a hole collection layer 35 on the photoactive layer 34;

Step 306: making an anode 36 on the hole collection layer 35;

Preferably, the specific method for making the buffer layer 37 on the cathode 32 can be selected from thermal evaporation, sputtering, sol-gel, electron beam deposition, chemical synthesis or self-assembly, or any other conventional method, it is believed that the specific method The process methods are common knowledge in the field; other specific structures, manufacturing methods and principles can be the same as those in the first, second or third embodiment, and will not be repeated here.

Sixth Embodiment

Referring to FIG. 4 , FIG. 4 is a schematic diagram of the structure distribution of an organic solar cell according to the sixth embodiment of the present invention. 4, the solar cell 10 is an inverted structure, specifically including a substrate 41, and a cathode 42, an electron transport layer 43, a photoactive layer 44, a hole transport layer 45, a buffer layer 47, and a substrate 41 sequentially formed on the substrate 41. Anode 46, the main difference between the sixth embodiment and the fifth embodiment is that the buffer layer 47 is between the anode 46 and the hole transport layer 45, that is, the buffer layer 47 and the hole transport layer 45 The anode 46 is adjacent to each other. Preferably, the material of the buffer layer 47 is transition metal oxide or fluoride.

Referring to the sequence block diagram of the fabrication steps of the organic solar cell 10 according to the sixth embodiment shown in FIG. 9 , the fabrication sequence includes:

Step 401: making cathode 42 on substrate 41;

Step 402: making an electron transport layer 43 on the cathode 42;

Step 403: making a photoactive layer 44 on the electron transport layer 43;

Step 404: forming a hole collection layer 45 on the photoactive layer 44;

Step 405: making a buffer layer 47 on the hole collection layer 45;

Step 406: making the anode 46 on the buffer layer 47;

The remaining specific structures, manufacturing methods and principles can be the same as those of the fifth embodiment, and will not be repeated here.

Seventh Embodiment Mode

Referring to FIG. 5 , FIG. 5 is a schematic diagram of the structural distribution of an organic solar cell according to the seventh embodiment of the present invention. Referring to FIG. 5, the solar cell 10 is an inverted structure, specifically including a substrate 51, and a cathode 52, an electron transport layer 53, a photoactive layer 54, and an anode 55 sequentially formed on the substrate 51. Compared with the first embodiment, the main difference is that the hole transport layer is not included.

Referring to FIG. 10 , which is a sequence block diagram of the fabrication steps of the organic solar cell 10 according to the fifth embodiment, the fabrication sequence includes:

Step 501: making cathode 52 on substrate 51;

Step 502: making an electron transport layer 53 on the cathode 52;

Step 503: making a photoactive layer 54 on the electron transport layer 53;

Step 504: making an anode 55 on the photoactive layer 54;

The remaining specific structures, manufacturing methods and principles can be the same as those in the first or second or third or fifth or sixth embodiment, and will not be repeated here.

The transparent material in the present invention refers to a material with better light transmittance, including transparent, translucent, and general transparency materials.

Of course, further explanations will be made on the basis of the technical solutions in the description in combination with the above embodiments, the principle is the same as that of the fifth or sixth embodiment of the present invention, and on the basis of the core technical content disclosed in the present invention, the present invention The solar cells described above can also be combined with other more optimized structures to further improve the implementation effect of the present invention. It is believed that these combinations belong to the conventional choices or common knowledge of those skilled in the art. As long as the core technical content described in the present invention is adopted, they all belong to The protection scope of the claims of the present invention, therefore, the specific optimized structures are not listed one by one.

For the technical content that is not specifically involved or developed in the present invention, such as the specific process parameters in the production steps of the organic solar cell 10, etc., it is believed that they are all conventional choices of those skilled in the art. The relevant technical content, the patent publication number is CN102751439A, and no specific text description will be given here.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. An organic solar cell, characterized in that, comprising: an anode that collects holes; a cathode that collects electrons; a photoactive layer generating hole-electron pairs, between said anode and cathode; An electron transport layer, between the cathode and the photoactive layer; Wherein, the electron transport layer is an organic small molecule layer, and the organic small molecule layer is doped with a luminescent material, and for a wavelength band that is not absorbed by the photoactive layer or has a low light absorption efficiency, the luminescent material absorbs the energy of the wavelength band , and emit a light band that is easily absorbed by the photoactive layer, thereby improving the light absorption efficiency of the photoactive layer. 2. The organic solar cell according to claim 1, further comprising a hole transport layer interposed between the anode and the photoactive layer. 3. The organic solar cell according to claim 1, wherein the luminescent material is selected from the group consisting of Ir(ppy)3, Ir(ppy)2(acac), Ir(mppy)3, Ir(pq)2 (acac), Ir(bt)2(acac), Ir(MDQ)2(acac), Ir(pq)3, Ir(flq)2(acac), Ir(fliq)2(acac), Ir(piq) 2(acac), Ir(piq)3, Ir(btp)2(acac), C545T, DCM, DCJTB, Perylene, DPAVBi, DPAVB, BDAVBi, FirPic or a mixture of Rubrene. 4. organic solar cell as claimed in claim 1, is characterized in that, the organic small molecule of described organic small molecule layer is one or more in Alq3, BCP, BPhen, Liq, BAlq, 3TPYMB, TAZ or TPBi A mix of species. 5. The organic solar cell according to claim 1, wherein the doping concentration of the luminescent material in the organic small molecule layer is equal to or less than 50%. 6. The organic solar cell according to claim 1, wherein the thickness of the electron transport layer is in the range of 1-200 nm. 7. The organic solar cell according to claim 1, characterized in that, the solar cell is an inverted structure, and the inverted structure means that the cathode acts as a sunlight receiving surface, and sunlight enters the solar cell through the cathode. the photoactive layer. 8. The organic solar cell according to claim 7, wherein the cathode is formed on the substrate, and its material is TCO of a transparent material or TCO containing a dopant, and the material of the anode is a metal . 9. The organic solar cell according to claim 1, further comprising a buffer layer for adjusting the intensity distribution of light in each layer, and the buffer layer is adjacent to the cathode or the anode . 10. The organic solar cell as claimed in claim 7 or 8, characterized in that the preparation method of the electron transport layer is selected from co-evaporation, solution spin coating, spray coating, screen printing, inkjet printing, chemical synthesis , electron beam deposition or self-assembly.