CN107123737B - Undoped high efficiency organic photovoltaic cells - Google Patents

Abstract

The invention discloses a non-doped high-efficiency organic photovoltaic cell, which comprises a transparent insulating substrate, a transparent anode electrode layer sequentially stacked on the transparent insulating substrate, an anode modification layer, a matrix layer, a cathode modification layer, and a cathode electrode layer , and several splitting layers arranged in the matrix layer. The splitting layer provides several dissociation interfaces for excitons, which can effectively improve the energy conversion efficiency of organic solar cells.

Description

Non-doped high-efficiency organic photovoltaic cells

technical field

The invention belongs to the technical field of photoelectric conversion devices, and in particular relates to a non-doped high-efficiency organic photovoltaic cell.

Background technique

The research on organic solar cells began in 1958. Kearns and Calvin sandwiched magnesium phthalocyanine dye (MgPc) between two electrodes with different work functions to make a "sandwich" structure, thus obtaining an open circuit voltage of 200 mV, but Its short-circuit current output is very low, so its energy conversion efficiency is relatively low. This single-layer organic solar cell structure was replaced by C.W.Tang in 1986 with a double-layer heterojunction structure, which achieved an energy conversion efficiency of 1%. The reason why the energy conversion efficiency has been greatly improved is that the double-layer heterojunction structure provides an efficient interface for exciton splitting, that is to say, the double-layer heterostructure allows the neutral electron-hole pairs to split into free Carriers become easier. However, since there is only one heterojunction interface in a double-layer dielectric structure battery, and the exciton diffusion length of common organic materials is short, much smaller than its optical absorption length, those photogenerated excitons far away from the heterojunction interface cannot be dissociated. A photocurrent is formed, which greatly limits the energy conversion efficiency of organic photovoltaic cells. To this end, people have developed a donor-acceptor heterojunction device structure based on the doping of two materials. The bulk heterojunction structure greatly increases the interface of the heterojunction, which can effectively promote the dissociation of excitons, but the structure of the battery is also more complicated. At the same time, the performance of the battery is greatly affected by the mixing ratio of the two donor and acceptor materials. It is necessary to precisely control the doping ratio of the donor or acceptor, which increases the difficulty of device preparation and is not conducive to large-scale industrial production. The present invention aims to overcome the problems of few exciton dissociation interfaces, low battery efficiency and complex preparation process of hybrid heterojunction structure battery devices in the background technology, and proposes a new type of non-doped Heterogeneous high-efficiency organic photovoltaic cells.

Contents of the invention

In order to overcome the deficiencies of the prior art in the background art, the object of the present invention is to provide a non-doped high-efficiency organic photovoltaic cell, which is provided with a splitting layer, increases the exciton dissociation interface, and avoids complicated doping process.

In order to realize the above-mentioned purpose of the invention, the technical scheme of the present invention is as follows:

A non-doped high-efficiency organic photovoltaic cell, characterized in that the non-doped high-efficiency organic photovoltaic cell comprises a transparent insulating substrate, a transparent anode electrode layer formed sequentially on the transparent insulating substrate, and an anode modification layer , a matrix layer, a cathode modification layer, a cathode electrode layer, and a first splitting layer, a second splitting layer,,, and an Nth splitting layer (N is an integer greater than or equal to 1) arranged in the matrix layer; The thickness of each layer of the splitting layer is 2-5 nm; the distance between the first splitting layer and the anode modification layer is greater than 5 nm; the distance between the Nth modification layer and the cathode modification layer is greater than 5 nm ; The distance between adjacent splitting layers is greater than 5 nm.

Further, the material of the transparent insulating substrate is quartz glass, silicate glass, high silica glass, soda lime glass, polyvinyl chloride, polycarbonate or polyester; the thickness of the transparent insulating substrate is 1.1～1.5mm.

Further, the transparent anode electrode layer is a conductive film made of indium tin oxide, zinc aluminum oxide, zinc gallium oxide, indium zinc oxide, gold, aluminum, silver or carbon nanotubes; the thickness of the transparent anode electrode layer is It is 80-120nm.

Further, the anode modification layer is a high work function transparent metal oxide, including MoO3, WoO3, V2O5, with a thickness of 2-10 nm.

Further, the matrix layer is fullerene, including C60 and C70, with a thickness of 40-100 nm.

Further, the splitting layer is one or more of TPD, TAPC, CBP, NPB, and 2-TNATA.

Further, the cathode modification layer is BCP, Bphen or LiF, with a thickness of 1-10 nm.

Further, the material of the cathode electrode layer is Ag, Al, Ca-Al alloy, Mg-Ag alloy, ITO; the thickness of the cathode electrode layer is 80-120 nm.

The thickness of the splitting layer described in the present invention is extremely thin, at 2-5 nm, after the excitons are dissociated, the electrons between the splitting layer and the anode and the holes between the splitting layer and the cathode can pass through The energy level transport can also cross the splitting layer through the Suichuan way, and finally be collected by the respective electrodes. The present invention increases the exciton dissociation interface by setting a splitting layer in the acceptor matrix layer. For every additional cleaving layer, two exciton dissociation interfaces are added. Compared with the traditional double-layer heterojunction battery, the dissociation interface of excitons is greatly increased, which improves the energy conversion efficiency of the battery. Compared with bulk heterojunction cells, the complex doping process is avoided, and the cell structure is simpler, which is suitable for industrial production of organic photovoltaic cells.

Description of drawings

Figure 1 is a schematic diagram of the structure of a non-doped high-efficiency organic photovoltaic cell according to an embodiment of the present invention.

Detailed ways

In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention will be further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

Please refer to FIG. 1 , which shows a schematic structural diagram of a non-doped high-efficiency organic photovoltaic cell according to an embodiment of the invention.

A non-doped high-efficiency organic photovoltaic cell, characterized in that the non-doped high-efficiency organic photovoltaic cell comprises a transparent insulating substrate, a transparent anode electrode layer formed sequentially on the transparent insulating substrate, and an anode modification layer , a matrix layer, a cathode modification layer, a cathode electrode layer, and a first splitting layer, a second splitting layer,,, and an Nth splitting layer (N is an integer greater than or equal to 1) arranged in the matrix layer; The thickness of each layer of the splitting layer is 2-5 nm; the distance between the first splitting layer and the anode modification layer is greater than 5 nm; the distance between the Nth modification layer and the cathode modification layer is greater than 5 nm ; The distance between adjacent splitting layers is greater than 5 nm. ,

The material of the above-mentioned transparent insulating substrate is preferably transparent glass such as quartz glass, silicate glass, high silica glass or soda lime glass, or polyvinyl chloride (PVC), polycarbonate (PC) or polyester (PET) etc. The transparent insulating plastic preferably has a thickness of 1.1-1.5 mm.

The material of the above-mentioned transparent anode electrode layer is preferably indium tin oxide (ITO), and its thickness is preferably 80-200 nm. Since the transparent anode electrode layer is made of transparent conductive material or metal film, and is thin in thickness, it can function as an electrode without affecting the transmission of sunlight. The transparent anode electrode layer is also the anode of the non-doped high-efficiency organic photovoltaic cell, and it can be etched into a stripe pattern by using a photolithographic etching method, thereby forming a stripe pattern electrode.

The above-mentioned anode modification layer is preferably a high work function inorganic metal oxide material, such as at least one of molybdenum trioxide (MoO3), tungsten trioxide (WoO3) or vanadium pentoxide (V2O5), the thickness of the anode modification layer Preferably it is 2 to 10 nm. Since the anode modification layer has almost no light absorption in the visible light region, its loss of sunlight is very small and can be ignored, so most of the sunlight is still absorbed by the photosensitive layer. The existence of the anode modification layer is to modify the transparent anode electrode layer and improve the work function of the transparent anode electrode layer. Increase the built-in electric field of the battery to promote the collection of dissociated electrons and holes by the electrodes.

The above-mentioned matrix layer is preferably fullerene, including C60 and C70, etc., and its thickness is preferably 40-100 nm. The matrix layer is the main photosensitive region that absorbs light to generate photocurrent. Its function is to generate electron-hole pairs with a certain binding force after the photosensitive layer absorbs photon energy, that is, excitons, and the excitons are electrically neutral. The excitons are split into free carriers under the action of the interface electric field between the splitting layer and the matrix layer, and the free carriers drift to the two electrodes in the matrix layer, thereby forming a photocurrent output.

The aforementioned splitting layer is one or more of TPD, TAPC, CBP, NPB, and 2-TNATA.

The above-mentioned cathode modification layer is BCP, Bphen or LiF, with a thickness of 1-10 nm.

The above-mentioned cathode electrode layer is made of metal thin films such as Ag, Al, Ca-Al alloy, Mg-Ag alloy, etc., and the thickness of the cathode electrode layer is 80-120nm. The cathode electrode layer is also the cathode of the single-layer organic solar cell.

The main reason why the efficiency of traditional double-layer organic solar cells is not high is that the photogenerated excitons in the cells cannot be effectively split. Exciton splitting is a process that mainly occurs at the donor-acceptor interface. However, in bilayer organic solar cells, there is only one donor–acceptor interface for exciton splitting. Most of the excitons that cannot diffuse to this interface will recombine and have no effect on the photogenerated current, which is the main reason for the low efficiency of bilayer organic solar cells. Based on this theory, this embodiment sets one or more splitting layers in the matrix layer, which increases the number of interfaces for exciton dissociation, provides more exciton dissociation regions, and increases the photocurrent and energy of the battery. conversion efficiency. When C70 is used as the matrix layer, the energy conversion efficiency of the non-doped organic photovoltaic cell in this example is as high as 2%, while for the double-layer organic solar cell, due to the lack of an effective exciton splitting interface, its efficiency is generally low. Very low, for example, the energy conversion efficiency of an existing organic solar cell without a splitting layer is below 1%. When C60 is used as the matrix layer, the energy conversion efficiency of the non-doped organic photovoltaic cell in this embodiment is as high as 1%, but for the double-layer organic solar cell, due to the lack of an effective exciton splitting interface, its efficiency is generally low. Very low, the energy conversion efficiency of an organic solar cell without a splitting layer is below 0.5%. Compared with the existing double-layer organic solar cells, the energy conversion efficiency of the organic solar cells of this embodiment is significantly improved.

The working principle of the single-layer organic solar cell in this embodiment is as follows: when sunlight hits the transparent insulating substrate, since the transparent insulating substrate is transparent, the transparent anode electrode layer is made of transparent conductive material, and the anode modification layer is transparent, Therefore, the loss of sunlight is very small and can be ignored. Therefore, most of the sunlight passes through the transparent insulating substrate, the transparent anode electrode layer and the electric field enhancement layer to the substrate layer and is absorbed by the substrate layer. After the layer absorbs the photon energy of sunlight, electron-hole pairs with a certain binding force are generated, that is, excitons. Excitons are dissociated into free electrons and holes at the interface between the nearest splitting layer and the matrix layer. Due to the work function difference between the transparent anode electrode layer and the cathode electrode layer, internal organic solar cell devices are generated. Build an electric field. Under the action of the above-mentioned built-in electric field, free electrons and holes drift to the transparent anode electrode layer and cathode electrode layer respectively in the photosensitive layer, thereby forming photocurrent output.

Several specific examples of the present invention are given below, and it should be understood that the following examples are only specific applications of the present invention, and are not intended to limit the present invention.

Embodiment one

Non-doped high-efficiency organic photovoltaic cells, the device structure is: transparent insulating substrate Glass 1.2 mm/transparent anode electrode layer ITO 200 nm/anode modification layer MoO3 5 nm/C70 15 nm/first split layer TAPC 5 nm/ C70 15nm/ second split layer TAPC 5 nm/ C70 15 nm/ third split layer TAPC 5 nm/ C70 15 nm/ cathode modification layer Bphen 5 nm/ cathode electrode Al 100 nm, wherein the matrix layer is 60 nm of C70, There are three splitting layers in the battery, that is, N=3, which can form six organic heterojunction interfaces for exciton dissociation. The distance between the first splitting layer and the MoO3 anode modification layer is greater than 5 nm, and the third splitting layer The distance from the Bphen cathode modification layer is greater than 5 nm, the distance between the first split layer and the second split layer is greater than 5 nm, and the distance between the second split layer and the third split layer is greater than 5 nm.

Embodiment two

Non-doped high-efficiency organic photovoltaic cells, the device structure is: transparent insulating substrate Glass 1.2 mm/transparent anode electrode layer ITO 200 nm/anode modification layer MoO3 5 nm/C60 10 nm/first splitting layer NPB 2 nm/ C60 10 nm/ second splitting layer NPB 2 nm/ C60 10 nm/ third splitting layer NPB 2 nm/ C60 10 nm/ fourth splitting layer NPB 2nm/ C60 10 nm/ cathode modification layer BCP 10 nm/ cathode electrode Ag 80 nm, in which the matrix layer is 40 nm C60, there are four splitting layers in the battery, that is, N=4, which can form 8 organic heterojunction interfaces for exciton dissociation.

Embodiment three

N=1, Glass 1.2 mm/transparent anode electrode layer ITO 200 nm/anode modification layer MoO3 5 nm/C70 25nm/first splitting layer TPD 5 nm/C70 25 nm/cathode modification layer BCP 10 nm/cathode electrode Ag 80 nm, where the matrix layer is 50 nm C70, and the splitting layer in the cell is 5 nm TPD, which can form two organic heterojunction interfaces for exciton dissociation.

Embodiment four

N=2, Glass 1.2 mm/transparent anode electrode layer ITO 200 nm/anode modification layer MoO3 5 nm/C60 20nm/first split layer CBP 2 nm/ C60 20 nm/second split layer CBP 2 nm/C60 20 nm/cathode modification layer BCP10 nm/cathode electrode Ag 80 nm, the matrix layer is 60 nm C60 layer, the splitting layer in the battery is 5 nm TPD, there are 2 splitting layers, which can form 4 organic heterogeneous Junction interface for exciton dissociation.

Claims (7)

1. a kind of undoped high efficiency organic photovoltaic cells, it is characterised in that: the undoped high efficiency organic photovoltaic cells, Including transparent insulating substrate, the transparent anode electrode layer to be formed, anode modification layer, matrix are stacked gradually on transparent insulating substrate Layer, cathodic modification layer, negative electrode layer, and be arranged in hypothallus the first splitting layer, the second splitting layer ..., N splits Parting is formed, and N is the integer more than or equal to 1；Described every layer of the layer of splitting with a thickness of 2~5 nm；First splitting Distance of the layer apart from anode modification layer is greater than 5 nm；Distance of the N splitting layer apart from cathodic modification layer is greater than 5 nm；Phase The distance of neighbour's splitting layer is greater than 5 nm, and the hypothallus is C60 or C70,40~100 nm of thickness.

2. a kind of undoped high efficiency organic photovoltaic cells according to claim 1, it is characterised in that: described is transparent exhausted The material of edge substrate is quartz glass, silicate glass, vagcor, soda-lime glass, polyvinyl chloride, polycarbonate or poly- Ester；The transparent insulating substrate with a thickness of the .5 of 1 .1~1 mm.

3. a kind of undoped high efficiency organic photovoltaic cells according to claim 1, it is characterised in that: the transparent sun The material of pole electrode layer is tin indium oxide；The transparent anode electrode layer with a thickness of 80~200 nm.

4. a kind of undoped high efficiency organic photovoltaic cells according to claim 1, it is characterised in that: the anode is repaired Decorations layer is one of molybdenum trioxide, tungstic acid or vanadic anhydride, thickness 2-10 nm.

5. a kind of undoped high efficiency organic photovoltaic cells according to claim 1, which is characterized in that the splitting layer For one or more of TPD, TAPC, CBP, NPB, 2-TNATA.

6. a kind of undoped high efficiency organic photovoltaic cells according to claim 1, it is characterised in that: the cathode is repaired Adoring layer is BCP, Bphen or LiF, thickness 1-10 nm.

7. a kind of undoped high efficiency organic photovoltaic cells according to claim 1, it is characterised in that: the cathode electricity The material of pole layer is Ag, Al, Ca-Al alloy, Mg-Ag alloy, ITO；The negative electrode layer with a thickness of 80~120 nm。