Quantum dot photovoltaic device and preparation method thereof

Abstract

The present invention discloses a quantum dot photovoltaic device and a preparation method thereof. The preparation method comprises the following steps: using zinc alloy as a target material, adopting a vacuum coating method to prepare a zinc-doped metal oxide film on an AZO substrate; preparing a quantum dot photosensitization absorption layer on the zinc-doped metal oxide film; preparing an anode on the quantum dot photosensitization absorption layer to obtain the quantum dot photovoltaic device. The zinc-doped metal oxide film prepared by the method of the present invention is firmly bonded to the AZO substrate and has a dense surface. Therefore, when the zinc-doped metal oxide film is used as an electron transport layer, the contact resistance between the zinc-doped metal oxide film and the AZO substrate and the quantum dot photosensitization absorption layer is small, so that the migration rate of carriers inside the device is large, which is conducive to improving the carrier transport efficiency inside the device. At the same time, the energy level difference between the zinc-doped metal oxide film and the AZO substrate is small, which is also conducive to improving the carrier transport efficiency inside the device.

Description

Technical Field

[0001] The present invention relates to the field of quantum dot light-emitting devices, and in particular to a quantum dot photovoltaic device and a preparation method thereof. Background Art

[0002] Quantum dots are nanoparticles with a diameter between 1 and 10 nm. Due to the quantum confinement of electrons and holes, quantum dot materials transform their previously continuous energy band structure into a discrete energy level structure, exhibiting excellent semiconductor properties. Quantum dot materials possess optical properties such as a broad excitation spectrum, a narrow emission spectrum, tunable emission wavelength, and high luminous efficiency. They are believed to have broad application prospects in optoelectronic displays, medical monitoring, biosensors, and other fields, and have become a research hotspot.

[0003] The basic structure of a quantum dot photovoltaic device includes a conductive glass substrate, an electron transport layer, a quantum dot layer, a hole transport layer, and a metal electrode. As the most commonly used material for the electron transport layer, nano-titanium dioxide thin films are non-toxic, environmentally friendly, highly transparent, and have good photostability. Despite this, the application of nano-titanium dioxide as an electron transport layer material in photovoltaics still faces many limitations. Currently, the titanium dioxide electron transport layer on solar cells is mainly prepared by spin-coating a nano-titanium dioxide dispersion or a titanium dioxide precursor sol. The titanium dioxide film prepared by this method has a weak bond with the conductive glass substrate, resulting in a large contact resistance between the two. At the same time, due to the energy level difference between the conductive glass substrate and the titanium dioxide film, there is a certain potential barrier for electrons to migrate between the conductive glass substrate and the electron transport layer, which hinders the migration rate of electrons within the photovoltaic device. The above two factors increase the internal resistance of the device and limit further improvements in the device's photoelectric performance.

[0004] Therefore, the existing technology still needs to be improved and developed. Summary of the Invention

[0005] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a quantum dot photovoltaic device and a preparation method thereof, aiming to solve the problem that the electron transport layer prepared by the existing method has weak bonding with the AZO substrate.

[0006] The technical solutions of the present invention are as follows:

[0007] A method for preparing a quantum dot photovoltaic device, comprising the steps of:

[0008] A zinc-doped metal oxide film is prepared on an AZO substrate using a zinc alloy as a target material by a vacuum coating method; wherein the zinc alloy is an alloy composed of zinc and a non-zinc metal;

[0009] preparing a quantum dot photosensitized absorption layer on the zinc-doped metal oxide film;

[0010] An anode is prepared on the quantum dot photosensitized absorption layer to obtain the quantum dot photovoltaic device.

[0011] A quantum dot photovoltaic device comprises: an AZO substrate, an electron transport layer, a quantum dot photosensitized absorption layer and an anode stacked in sequence; wherein the electron transport layer comprises a zinc-doped metal oxide film.

[0012] Beneficial effect: The present invention uses zinc alloy as a target material and prepares a zinc-doped metal oxide film with a smooth and dense surface that is firmly bonded to the AZO substrate by a vacuum coating method. The zinc-doped metal oxide film prepared by this method is firmly bonded to the AZO substrate and has a dense surface. Therefore, when the zinc-doped metal oxide film is used as an electron transport layer, the contact resistance between the zinc-doped metal oxide film and the AZO substrate and the quantum dot photosensitization absorption layer is small, so that the migration rate of carriers inside the device is large, which is conducive to improving the carrier transport efficiency inside the device, thereby improving the photoelectric performance of the quantum dot photovoltaic device. At the same time, since the main material of the AZO substrate is zinc oxide, and the zinc-doped metal oxide film (as an electron transport layer) also contains zinc oxide, the energy level similarity between the electron transport layer and the AZO substrate is increased, so that the energy level difference between the electron transport layer and the AZO substrate is small, and the migration barrier of carriers between the electron transport layer and the electrode is small, which is also conducive to improving the carrier transport efficiency inside the device, thereby further improving the photoelectric performance of the quantum dot photovoltaic device. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The figure is a schematic flow chart of a method for preparing a quantum dot photovoltaic device provided in an embodiment of the present invention.

[0014] Figure 2 Schematic diagram of the structure of a quantum dot photovoltaic device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0015] The present invention provides a quantum dot photovoltaic device and a method for preparing the same. To make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. The embodiments of the present invention provide a method for preparing a quantum dot photovoltaic device, such as Figure 1 As shown, the steps include:

[0016] S10, using a zinc alloy as a target material and adopting a vacuum coating method to prepare a zinc-doped metal oxide thin film on an AZO substrate; wherein the zinc alloy is an alloy composed of zinc and a non-zinc metal;

[0017] S20, preparing a quantum dot photosensitization absorption layer on the zinc-doped metal oxide film;

[0018] S30, preparing an anode on the quantum dot photosensitized absorption layer to obtain the quantum dot photovoltaic device.

[0019] The embodiment of the present invention uses zinc alloy as a target material and prepares a zinc-doped metal oxide film with a smooth and dense surface that is firmly bonded to an AZO substrate (aluminum-doped zinc oxide transparent conductive glass) by a vacuum coating method. The zinc-doped metal oxide film prepared by this method is firmly bonded to the AZO substrate and has a dense surface. Therefore, when the zinc-doped metal oxide film is used as an electron transport layer in a photovoltaic device, the contact resistance between the AZO substrate and other functional layers of the device (such as a quantum dot photosensitized absorption layer) is small, so that the carrier migration rate inside the device is large, which is conducive to improving the carrier transport efficiency inside the device, thereby improving the photoelectric performance of the quantum dot photovoltaic device. At the same time, since the main material of the AZO substrate is zinc oxide, and the zinc-doped metal oxide film (as an electron transport layer) also contains zinc oxide, the energy level similarity between the electron transport layer and the AZO substrate is increased, so that the energy level difference between the electron transport layer and the AZO substrate is small, and the migration barrier of the carrier between the electron transport layer and the electrode is small, which is also conducive to improving the carrier transport efficiency inside the device, thereby further improving the photoelectric performance of the quantum dot photovoltaic device. In addition, the method is simple to operate and easy to industrialize, and has broad application prospects in the fields of solar cells, optoelectronic display devices and lighting technology.

[0020] In step S10, in one embodiment, the atomic ratio of the metal to zinc in the zinc alloy is 10:1 to 3. If the atomic ratio of the metal to zinc is too large, the zinc doping level in the electron transport layer is too low, which is not conducive to reducing the carrier migration barrier between the electron transport layer and the AZO substrate. If the atomic ratio of the metal to zinc is too small, the zinc doping level in the electron transport layer is too high, resulting in a large barrier for carrier migration in the electron transport layer and the quantum dot photosensitized absorption layer, which is not conducive to improving the electron transport efficiency within the device.

[0021] In one embodiment, the zinc alloy includes, but is not limited to, one or more of a zinc-titanium alloy, a zinc-tin alloy, a zinc-nickel alloy, and a zinc-aluminum alloy. Correspondingly, the zinc-doped titanium oxide film, zinc-doped tin oxide film, zinc-doped nickel oxide film, and zinc-doped aluminum oxide film prepared using the method of the embodiment of the present invention are not limited to one or more of the above.

[0022] In one embodiment, the zinc-doped metal oxide film has a thickness of 20 to 100 nm. If the zinc-doped metal oxide film is too thin, the electron transport layer cannot completely cover the conductive electrode, which will affect the performance of the photovoltaic device. If the zinc-doped metal oxide film is too thick, the resistance of the electron transport layer increases, and the series resistance of the photovoltaic device increases, which reduces the efficiency of the photovoltaic device.

[0023] In one embodiment, step S10 specifically includes:

[0024] S11, placing the AZO substrate and the zinc alloy target on the anode and cathode in the coating chamber respectively;

[0025] S12. In an atmosphere of oxygen and inert gas, the AZO substrate is heated to a preset temperature, a power supply is started, and evaporation is performed at a preset power to obtain a zinc-doped metal oxide thin film by evaporation on the AZO substrate.

[0026] In an embodiment of the present invention, an AZO substrate and a zinc alloy target are placed on the anode and cathode in a coating chamber, respectively. When the power is turned on, electrons are accelerated between the two poles under the action of a strong electric field, generating high-energy electrons. During the movement, the high-energy electrons collide with the oxygen and inert gas in the coating chamber, transferring energy to the gas molecules. When the energy of the gas molecules is greater than their ionization energy, the gas molecules undergo ionization to form oxygen positive ions and inert gas positive ions. Under the action of the electric field, the positive ions bombard the zinc alloy target on the cathode, forming zinc atomic vapor and metal atomic vapor. The free metal atomic vapor reacts with the oxygen in the coating chamber to generate metal oxide, and collides with the AZO substrate to form a nano-zinc-doped metal oxide film on the AZO substrate. The embodiment of the present invention can accurately control the thickness of the zinc-doped metal oxide film by adjusting the sputtering power and coating time. The method is simple to operate, low in cost, and easy to implement industrial applications.

[0027] In step S11, in one embodiment, the cleaned AZO substrate and zinc alloy target are transferred to a coating chamber, and are placed on an anode and a cathode in the coating chamber, respectively.

[0028] In step S12, in one embodiment, the step of forming the atmosphere of oxygen and inert gas includes: starting the vacuum pump, pumping the air pressure in the coating chamber to below 10Pa, closing the vacuum pump valve, introducing a certain proportion of oxygen and inert gas (such as argon) to normal pressure, opening the vacuum pump valve again, pumping the air pressure in the coating chamber to below 10Pa, repeating the above operation twice, and adjusting the air pressure in the coating chamber to the working pressure to ensure that there is only low-pressure oxygen and inert gas in the coating chamber.

[0029] In one embodiment, during the evaporation process, the pressure in the coating chamber is 0.2 to 2 Pa. That is, the operating pressure of the coating chamber is 0.2 to 2 Pa. If the operating pressure is too high, the evaporated particles are prone to collisions with gas molecules during movement, resulting in energy loss and affecting the adhesion and density of the deposited film. If the operating pressure is too low, the requirements for instrument hardware are too stringent, making it unsuitable for industrial applications.

[0030] In one embodiment, the volume ratio of oxygen to inert gas is 1:5 to 10. If the ratio is too large, the oxygen content in the coating chamber is high, oxygen is more easily ionized than inert gas, and the total amount of oxygen and inert gas positive ions generated by ionization of the ionization source increases, resulting in a rapid evaporation rate of the target material and an accelerated deposition rate of the electron transport layer on the conductive substrate, affecting the density of the film. If the ratio is too small, the oxygen content in the coating chamber is low, and the electron transport layer deposited on the conductive substrate is prone to oxygen vacancy defects, affecting the photoelectric performance of the photovoltaic device.

[0031] In one embodiment, the preset temperature is 400-600°C. If the reaction temperature is too low, the crystal structure of the metal oxide material in the electron transport layer becomes amorphous, resulting in poor electron mobility and poor optoelectronic device performance. If the reaction temperature is too high, the metal oxide crystal structure changes from anatase to rutile, and the electron mobility and charge diffusion coefficient both decrease significantly, resulting in poor device optoelectronic performance.

[0032] In one embodiment, the preset power is 200-500 W. If the sputtering power is too high, the electron transport layer will be deposited on the AZO substrate too quickly, resulting in reduced film density. If the sputtering power is too low, the electron transport layer will be deposited slowly, which is not conducive to industrial production.

[0033] In one embodiment, step S20 specifically includes: placing a substrate on which an electron transport layer has been prepared on a coating machine, spin-coating a prepared quantum dot solution of a certain concentration into a film, controlling the thickness of the quantum dot photosensitized absorption layer by adjusting the concentration of the solution, the spin-coating speed and the spin-coating time, and finally performing a heat treatment to remove the residual solvent to obtain the quantum dot photosensitized absorption layer.

[0034] In one embodiment, the concentration of the quantum dot solution is in the range of 10 to 50 mg / mL. If the concentration of the quantum dot material is too low, the quantum dot photosensitization absorption layer in the photovoltaic device will be too thin, resulting in relatively low light absorption efficiency. If the concentration of the quantum dot material is too high, the quantum dot photosensitization absorption layer will be too thick, and the quantum dot material will easily agglomerate, affecting the flatness of the photosensitization absorption layer and hindering the bonding of the various functional layers in the photovoltaic device.

[0035] In one embodiment, the spin coating speed is 1000-5000 rpm. If the spin coating speed is too low, the quantum dot photosensitizer absorption layer is too thick, and the quantum dot material is prone to agglomeration, affecting the flatness of the quantum dot photosensitizer absorption layer and hindering electron mobility in the photovoltaic device. If the spin coating speed is too high, the quantum dot photosensitizer absorption layer in the photovoltaic device is too thin, resulting in low light absorption efficiency.

[0036] In one embodiment, the spin coating time is 30 to 90 seconds. If the time is too short, the quantum dot photosensitizer absorber layer contains a large amount of unevaporated solvent, which can be easily damaged during the subsequent drying process, resulting in poor film formation. If the spin coating time is too long, production efficiency decreases.

[0037] In one embodiment, the purpose of the above-mentioned heating treatment is to completely remove the solvent molecules in the quantum dot photosensitization absorption layer to prevent the residual solvent from affecting the film-forming effect of the quantum dot photosensitization absorption layer.

[0038] In one embodiment, the heating temperature is 80-150° C. If the temperature is too low, the solvent molecules are difficult to completely remove. If the temperature is too high, the film structure of the quantum dot photosensitizer absorption layer is easily destroyed, affecting the photoelectric performance of the device.

[0039] In one embodiment, the heating time is 10 to 60 minutes. If the heating time is too short, the solvent molecules are difficult to completely remove. If the heating time is too long, the device preparation cycle becomes longer, which is not conducive to production.

[0040] In one embodiment, step S30 specifically includes: preparing a hole transport layer on the quantum dot photosensitized absorption layer, and preparing the anode on the hole transport layer to obtain the quantum dot photovoltaic device. By adding the hole transport layer, the hole transport efficiency can be improved, thereby improving the photoelectric performance of the quantum dot photovoltaic device.

[0041] In one embodiment, the step of preparing a hole transport layer on the quantum dot photosensitized absorption layer includes: placing a substrate on a coating machine and spin coating a prepared hole transport material solution into a film; controlling the film thickness by adjusting the concentration, spin coating speed and spin coating time of the solution, and then performing a heat treatment to remove the residual solvent to obtain the hole transport layer.

[0042] In one embodiment, the spin coating speed is 1000-5000 rpm. If the spin coating speed is too low, the hole transport layer is too thick; if the spin coating speed is too high, the hole transport layer is too thin; if the hole transport layer is too thin or too thick, it will lead to electron-hole imbalance in the device, thereby causing poor device performance.

[0043] In one embodiment, the concentration of the hole transport material solution is 10 to 50 mg / ml. If the concentration is too low, the hole transport layer in the photovoltaic device will be too thin. If the concentration is too high, the hole transport layer will be too thick. Both too thin and too thick hole transport layers can lead to electron-hole imbalance within the device, resulting in poor device performance.

[0044] In one embodiment, the spin coating time is 30 to 90 seconds. If the time is too short, the hole transport layer contains a large amount of solvent that has not been volatilized, resulting in poor film formation of the hole transport layer during the subsequent drying process. If the spin coating time is too long, production efficiency decreases.

[0045] In one embodiment, the purpose of the above-mentioned heat treatment is to completely remove the solvent molecules in the hole transport layer to prevent the residual solvent from affecting the film formation effect.

[0046] In one embodiment, the heating temperature is 50° C. to 150° C. If the temperature is too low, the solvent molecules are difficult to completely remove. If the temperature is too high, the film structure of the photovoltaic device functional layer is easily damaged, affecting the photoelectric performance of the device.

[0047] In one embodiment, the heating time is 10 to 60 minutes. If the heating time is too short, the solvent molecules are difficult to completely remove. If the heating time is too long, the functional layer structure of the device may be damaged, affecting the optoelectronic performance of the device.

[0048] In one embodiment, the step of preparing an anode on the hole transport layer includes: preparing the anode by vacuum thermal evaporation above the hole transport layer. During the evaporation process, a metal material (used as the anode material) is heated by a certain current electron beam bombardment in a vacuum environment, and is evaporated into metal atomic vapor. The metal atomic vapor then moves freely in the vacuum chamber and collides with the lower temperature substrate surface to condense and form a thin film, thus obtaining the anode.

[0049] In one embodiment, the current of the electron beam bombardment is 100-250A. If the current is too low, the metal material will be difficult to evaporate, making evaporation difficult. If the current is too high, a large amount of metal atomic vapor will be present in the vacuum chamber, causing the evaporation process to proceed rapidly, resulting in a decrease in the flatness of the metal electrode film, affecting the contact between the electrode and the hole transport layer, and hindering the transport of carriers in the device.

[0050] An embodiment of the present invention provides a quantum dot photovoltaic device, comprising: an AZO substrate, an electron transport layer, a quantum dot photosensitized absorption layer, and an anode stacked in sequence; wherein the electron transport layer comprises a zinc-doped metal oxide film.

[0051] In the embodiment of the present invention, quantum dot photovoltaic devices have various forms. This embodiment will mainly use the following Figure 2 The quantum dot photovoltaic device shown in FIG. Figure 2 As shown, the quantum dot photovoltaic device includes: an AZO substrate 1, an electron transport layer 2, a quantum dot photosensitized absorption layer 3, a hole transport layer 4 and an anode 5 stacked from bottom to top; wherein, the electron transport layer 2 includes a zinc-doped metal oxide film.

[0052] The electron transport layer described in the embodiment of the present invention is a zinc-doped metal oxide film. The zinc-doped metal oxide film is firmly bonded to the AZO substrate and has a dense surface. Therefore, when the zinc-doped metal oxide film is used as an electron transport layer, the contact resistance between the zinc-doped metal oxide film and the AZO substrate and the quantum dot photosensitized absorption layer is small, so that the carrier migration rate inside the device is large, which is conducive to improving the carrier transport efficiency inside the device, thereby improving the photoelectric performance of the quantum dot photovoltaic device. At the same time, since the main material of the AZO substrate is zinc oxide, and the zinc-doped metal oxide film (as the electron transport layer) also contains zinc oxide, the energy level similarity between the electron transport layer and the AZO substrate is increased, so that the energy level difference between the electron transport layer and the AZO substrate is small, and the migration barrier of the carrier between the electron transport layer and the electrode is small, which is also conducive to improving the carrier transport efficiency inside the device, thereby further improving the photoelectric performance of the quantum dot photovoltaic device.

[0053] In one embodiment, the zinc-doped metal oxide film has a thickness of 20 to 100 nm. If the zinc-doped metal oxide film is too thin, it cannot completely cover the conductive electrode, which can affect the performance of the photovoltaic device. If the zinc-doped metal oxide film is too thick, the resistance of the electron transport layer increases, which in turn increases the series resistance of the photovoltaic device and reduces the efficiency of the photovoltaic device.

[0054] In one embodiment, the material of the hole transport layer can be selected from materials with good hole transport properties, for example, it can include but is not limited to poly (9,9-dioctylfluorene-CO-N-(4-butylphenyl) diphenylamine) (TFB), polyvinyl carbazole (PVK), poly (N, N'-bis (4-butylphenyl) -N, N'-bis (phenyl) benzidine) (Poly-TPD), 4,4',4"-tri (carbazole-9-yl) triphenylamine (TCTA), poly (3,4-ethylenedioxythiophene) -poly (styrene sulfonic acid) (PEDOT:PSS), 4,4'-bis (9-carbazole) biphenyl (CBP), NiO, MoO3 and the like. One or more.

[0055] In one embodiment, the material of the quantum dot photosensitization absorption layer may include one or more of the following: Group II-VI quantum dots, or core-shell structure quantum dots, or alloy structure quantum dot materials; Group III-V quantum dots, or core-shell structure quantum dots, or alloy structure quantum dot materials; organic-inorganic hybrid perovskite quantum dot materials; all-inorganic quantum dot materials.

[0056] In one embodiment, the quantum dot particle size is 2 to 10 nm. If the particle size is too small, the film-forming properties of the quantum dot material will be poor, and the energy resonance transfer effect between quantum dot particles will be significant, which is not conducive to the application of the material. If the particle size is too large, the quantum effect of the quantum dot material will be weakened, resulting in a decrease in the photoelectric performance of the material.

[0057] In one embodiment, the material of the anode includes one of aluminum (Al), silver (Ag), and gold (Au), or an alloy thereof. The above materials have low resistance, allowing carriers to be injected smoothly.

[0058] In one embodiment, the thickness of the anode is 20 to 200 nm. If the anode is too thin, the electrode is easily damaged, affecting the use of the device. If the electrode is too thick, raw material consumption increases, the evaporation time is prolonged, and production costs increase.

[0059] It should be noted that the quantum dot photovoltaic device of the embodiment of the present invention may further include one or more of the following functional layers: a hole injection layer disposed between the hole transport layer and the anode, and an electron injection layer disposed between the electron transport layer and the cathode.

[0060] The present embodiment is described in detail below through specific examples.

[0061] Example 1

[0062] (1) Electron transport layer vapor deposition process

[0063] The cleaned AZO substrate and titanium-zinc target (titanium:zinc atomic ratio of 10:1) were transferred to the coating chamber respectively and connected to the anode and cathode respectively. Start the vacuum pump and pump the pressure of the coating chamber to below 10Pa. Close the vacuum pump valve and introduce a mixed gas of oxygen and argon with a volume ratio of 1:6 to normal pressure. Open the vacuum pump valve again and pump the pressure of the coating chamber to below 10Pa. Repeat the above operation twice and adjust the pressure of the coating chamber to 0.5Pa to ensure that there are only low-pressure oxygen and argon in the coating chamber. Next, heat the AZO substrate to 500℃ and keep the temperature constant. Then, start the power supply and perform sputtering evaporation at a power of 260W. When the zinc-doped titanium dioxide film reaches 30nm, stop evaporation, cool the coating chamber, and remove the AZO substrate with zinc-doped titanium dioxide film.

[0064] (2) Preparation process of quantum dot photovoltaic devices

[0065] A: First, the AZO substrate with the zinc-doped titanium dioxide electron transport layer deposited in (1) above was fixed on a spin coater, 0.2 ml of a 30 mg / ml CdSe / CdS quantum dot n-octane solution was taken and dropped onto the electron transport layer, and the solution was spin-coated at 3000 rpm for 40 seconds to prepare a quantum dot photosensitizer absorption layer. The spin-coated substrate was heated to 80°C and heat-treated for 30 minutes to remove the residual solvent, thereby completing the preparation of the quantum dot photosensitizer absorption layer.

[0066] B: Next, re-mount the wafer on the spin coater and add 0.2 ml of a 10 mg / ml P3HT solution in dichlorobenzene dropwise onto the quantum dot photosensitizer layer. Spin-coat the wafer at 3000 rpm for 30 seconds to create a hole transport layer. Heat the spin-coated wafer to 80°C for 30 minutes to remove any remaining solvent, completing the hole transport layer.

[0067] C: The wafer is transferred to an evaporation machine, and an electron beam with a current of 35A bombards the silver element, causing the silver element to evaporate into silver atomic vapor, forming a 100nm thick silver electrode above the hole transport layer, and encapsulating it to obtain the final quantum dot photovoltaic device.

[0068] Example 2

[0069] (1) Electron transport layer vapor deposition process

[0070] The cleaned AZO substrate and tin-zinc target (tin:zinc atomic ratio of 10:1) were transferred to the coating chamber and connected to the anode and cathode, respectively. The vacuum pump was started to reduce the pressure in the coating chamber to below 10 Pa. The vacuum pump valve was closed and a mixture of oxygen and argon with a volume ratio of 1:6 was introduced to atmospheric pressure. The vacuum pump valve was opened again to reduce the pressure in the coating chamber to below 10 Pa. This operation was repeated twice, and the pressure in the coating chamber was adjusted to 0.5 Pa to ensure that only low-pressure oxygen and argon were present in the coating chamber. Next, the AZO substrate was heated to 500°C and maintained at a constant temperature. The power supply was then turned on and sputtering was performed at a power of 260 W. When the zinc-doped tin dioxide film reached 30 nm, the evaporation was stopped, the coating chamber was cooled, and the AZO substrate with the zinc-doped tin dioxide film was removed.

[0071] (2) Preparation process of photovoltaic devices

[0072] A: First, the AZO substrate with the zinc-doped titanium dioxide electron transport layer deposited in (1) above was fixed on a spin coater, 0.2 ml of a 30 mg / ml CdSe / CdS quantum dot n-octane solution was taken and dropped onto the electron transport layer, and the solution was spin-coated at 3000 rpm for 40 seconds to prepare a quantum dot photosensitizer absorption layer. The spin-coated substrate was heated to 80°C and heat-treated for 30 minutes to remove the residual solvent, thereby completing the preparation of the quantum dot photosensitizer absorption layer.

[0073] B: Next, re-mount the wafer on the spin coater and add 0.2 ml of a 10 mg / ml P3HT solution in dichlorobenzene dropwise onto the quantum dot photosensitizer layer. Spin-coat the wafer at 3000 rpm for 30 seconds to create a hole transport layer. Heat the spin-coated wafer to 80°C for 30 minutes to remove any remaining solvent, completing the hole transport layer.

[0074] C: The wafer is transferred to an evaporation machine, and an electron beam with a current of 100A bombards the silver element, causing the silver element to evaporate into silver atomic vapor, forming a 100nm thick silver electrode above the hole transport layer, and encapsulating it to obtain the final quantum dot photovoltaic device.

[0075] Example 3

[0076] (1) Electron transport layer vapor deposition process

[0077] The cleaned AZO substrate and titanium zinc target (titanium / zinc atomic ratio of 10:1) were transferred to the coating chamber respectively and connected to the anode and cathode respectively. Start the vacuum pump and pump the pressure of the coating chamber to below 10Pa. Close the vacuum pump valve and introduce a mixed gas with a volume ratio of oxygen and argon of 1:6 to normal pressure. Open the vacuum pump valve again and pump the pressure of the coating chamber to below 10Pa. Repeat the above operation twice and adjust the pressure of the coating chamber to 0.5Pa to ensure that there are only low-pressure oxygen and argon in the coating chamber. Next, heat the AZO substrate to 500℃ and keep the temperature constant. Then, start the power supply and perform sputtering evaporation at a power of 260W. After the zinc-doped titanium dioxide film reaches 30nm, stop evaporation, cool the coating chamber, and remove the AZO substrate with the zinc-doped titanium dioxide film.

[0078] (2) Preparation process of photovoltaic devices

[0079] A: First, the conductive glass with the nano-zinc-doped titanium dioxide electron transport layer deposited in (1) was fixed on a spin coater, 0.2 ml of a 30 mg / ml PbS quantum dot n-octane solution was added dropwise to the electron transport layer, and the solution was spin-coated at 3000 rpm for 40 seconds to prepare a quantum dot photosensitized absorption layer. The spin-coated sheet was heated to 80°C and heat-treated for 30 minutes to remove the remaining solvent, thereby completing the preparation of the quantum dot photosensitized absorption layer.

[0080] B: Next, re-mount the wafer on the spin coater and add 0.2 ml of a 10 mg / ml P3HT solution in dichlorobenzene dropwise onto the photosensitized absorption layer. Spin-coat the wafer at 3000 rpm for 30 seconds to create the hole transport layer. Heat the spin-coated wafer to 80°C for 30 minutes to remove any remaining solvent, completing the hole transport layer.

[0081] C: The wafer is transferred to an evaporation machine, and an electron beam with a current of 100A bombards the silver element, causing the silver element to evaporate into silver atomic vapor, forming a 100nm thick silver electrode above the hole transport layer, and encapsulating it to obtain the final quantum dot photovoltaic device.

[0082] Example 4

[0083] (1) Electron transport layer vapor deposition process

[0084] The cleaned AZO substrate and titanium zinc target (titanium / zinc atomic ratio of 10:1) were transferred to the coating chamber respectively and connected to the anode and cathode respectively. Start the vacuum pump and pump the pressure of the coating chamber to below 10Pa. Close the vacuum pump valve and introduce a mixed gas with a volume ratio of oxygen and argon of 1:6 to normal pressure. Open the vacuum pump valve again and pump the pressure of the coating chamber to below 10Pa. Repeat the above operation twice and adjust the pressure of the coating chamber to 0.5Pa to ensure that there are only low-pressure oxygen and argon in the coating chamber. Next, heat the AZO substrate to 500℃ and keep the temperature constant. Then, start the power supply and perform sputtering evaporation at a power of 260W. When the zinc-doped titanium dioxide film reaches 30nm, stop evaporation, cool the coating chamber, and remove the AZO substrate with zinc-doped titanium dioxide film.

[0085] (2) Preparation process of photovoltaic devices

[0086] A: First, the AZO substrate with the nano-zinc-doped titanium dioxide electron transport layer deposited in (1) above was fixed on a spin coater, 0.2 ml of a 30 mg / ml CsPbCl3 quantum dot n-octane solution was taken and dropped onto the electron transport layer, and the solution was spin-coated at 3000 rpm for 40 seconds to prepare a quantum dot photosensitizer absorption layer. The spin-coated wafer was heated to 80°C and heat-treated for 30 minutes to remove the residual solvent, thereby completing the preparation of the quantum dot photosensitizer absorption layer.

[0087] B: Next, re-mount the wafer on the spin coater and add 0.2 ml of a 10 mg / ml P3HT solution in dichlorobenzene dropwise onto the quantum dot photosensitizer layer. Spin-coat the wafer at 3000 rpm for 30 seconds to create a hole transport layer. Heat the spin-coated wafer to 80°C for 30 minutes to remove any remaining solvent, completing the hole transport layer.

[0088] C: The wafer is transferred to an evaporation machine, and an electron beam with a current of 100A bombards the silver element, causing the silver element to evaporate into silver atomic vapor, forming a 100nm thick silver electrode above the hole transport layer, and encapsulating it to obtain the final quantum dot photovoltaic device.

[0089] Example 5

[0090] (1) Electron transport layer vapor deposition process

[0091] The cleaned AZO substrate and titanium zinc target (titanium / zinc atomic ratio of 10:1) were transferred to the coating chamber respectively and connected to the anode and cathode respectively. Start the vacuum pump and pump the pressure of the coating chamber to below 10Pa. Close the vacuum pump valve and introduce a mixed gas with a volume ratio of oxygen and argon of 1:6 to normal pressure. Open the vacuum pump valve again and pump the pressure of the coating chamber to below 10Pa. Repeat the above operation twice and adjust the pressure of the coating chamber to 0.5Pa to ensure that there are only low-pressure oxygen and argon in the coating chamber. Next, heat the AZO substrate to 500℃ and keep the temperature constant. Then, start the power supply and perform sputtering evaporation at a power of 260W. When the zinc-doped titanium dioxide film reaches 30nm, stop evaporation, cool the coating chamber, and remove the AZO substrate with zinc-doped titanium dioxide film.

[0092] (2) Preparation process of photovoltaic devices

[0093] A: First, the AZO substrate with the nano-zinc-doped titanium dioxide electron transport layer deposited in (1) above was fixed on a spin coater, 0.2 ml of a 30 mg / ml CdSe / CdS quantum dot n-octane solution was taken and dropped onto the electron transport layer, and the solution was spin-coated at 3000 rpm for 40 seconds to prepare a quantum dot photosensitizer absorption layer. The spin-coated substrate was heated to 80°C and heat-treated for 30 minutes to remove the residual solvent, thereby completing the preparation of the quantum dot photosensitizer absorption layer.

[0094] B: Next, re-mount the wafer on the spin coater and add 0.2 ml of a 10 mg / ml P3HT solution in dichlorobenzene dropwise onto the quantum dot photosensitizer layer. Spin-coat the wafer at 3000 rpm for 30 seconds to create a hole transport layer. Heat the spin-coated wafer to 80°C for 30 minutes to remove any remaining solvent, completing the hole transport layer.

[0095] C: The wafer is transferred to an evaporation machine, and an electron beam with a current of 35A bombards the aluminum element, causing the aluminum element to evaporate into aluminum atomic vapor, forming a 100nm thick aluminum electrode above the hole transport layer, and encapsulating it to obtain the final quantum dot photovoltaic device.

[0096] In summary, the present invention provides a quantum dot photovoltaic device and a preparation method thereof. The present invention adopts zinc alloy as a target material, and prepares a zinc-doped metal oxide film that is firmly bonded to an AZO substrate and has a smooth and dense surface by a vacuum coating method. The zinc-doped metal oxide film prepared by this method has a small energy level difference with the AZO substrate as an electron transport layer, and the migration barrier of carriers between the electron transport layer and the electrode is small, which is conducive to improving the carrier transport efficiency inside the device, thereby improving the photoelectric performance of the quantum dot photovoltaic device. At the same time, the zinc-doped metal oxide film prepared by this method is firmly bonded to the AZO substrate and has a dense surface. Therefore, when the zinc-doped metal oxide film is used as an electron transport layer, the contact resistance between the AZO substrate and the quantum dot photosensitization absorption layer is small, so that the migration rate of carriers inside the device is large, which is also conducive to improving the carrier transport efficiency inside the device, thereby further improving the photoelectric performance of the quantum dot photovoltaic device.

[0097] It should be understood that the application of the present invention is not limited to the above examples. For those skilled in the art, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for preparing a quantum dot photovoltaic device, characterized in that: Including steps: A zinc-doped metal oxide film is prepared on an AZO substrate using a zinc alloy as a target material by vacuum coating; wherein the zinc alloy is an alloy composed of zinc and a non-zinc metal; and in the zinc alloy, the atomic ratio of the metal to zinc is 10:1-3; preparing a quantum dot photosensitized absorption layer on the zinc-doped metal oxide film; preparing an anode on the quantum dot photosensitized absorption layer to obtain the quantum dot photovoltaic device; The step of preparing a quantum dot photosensitized absorption layer on the zinc-doped metal oxide film specifically includes: forming a film of a quantum dot solution having a concentration range of 10 to 50 mg / mL on the zinc-doped metal oxide thin film, performing a heat treatment to remove the residual solvent, and obtaining the quantum dot photosensitized absorption layer; The zinc alloy includes one or more of zinc-titanium alloy, zinc-tin alloy, zinc-nickel alloy and zinc-aluminum alloy.

2. The method for preparing a quantum dot photovoltaic device according to claim 1, wherein: The step of preparing a zinc-doped metal oxide thin film on an AZO substrate by using a vacuum coating method using a zinc alloy as a target material specifically comprises: The AZO substrate and the zinc alloy target are placed on the anode and cathode in the coating chamber respectively; In an atmosphere of oxygen and inert gas, the AZO substrate is heated to a preset temperature, a power supply is started, and evaporation is performed at a preset power to obtain a zinc-doped metal oxide thin film by evaporation on the AZO substrate.

3. The method for preparing a quantum dot photovoltaic device according to claim 2, wherein: During the evaporation process, the air pressure in the coating chamber is 0.2-2 Pa; and / or The volume ratio of the oxygen to the inert gas is 1:5-10.

4. The method for preparing a quantum dot photovoltaic device according to claim 2, wherein: The preset temperature is 400-600° C.; and / or The preset power is 200~500W.

5. The method for preparing a quantum dot photovoltaic device according to claim 1, wherein: The thickness of the zinc-doped metal oxide film is 20-100 nm.

6. A quantum dot photovoltaic device, characterized in that: include: An AZO substrate, an electron transport layer, a quantum dot photosensitized absorption layer, and an anode are stacked in sequence; wherein the electron transport layer comprises a zinc-doped metal oxide film; The quantum dot photovoltaic device is prepared by the preparation method according to any one of claims 1 to 5.

7. The quantum dot photovoltaic device according to claim 6, characterized in that The electron transport layer is a zinc-doped metal oxide film.

8. The quantum dot photovoltaic device according to claim 6, characterized in that The thickness of the zinc-doped metal oxide film is 20-100 nm.

9. The quantum dot photovoltaic device according to claim 6, characterized in that The zinc-doped metal oxide film includes one or more of a zinc-doped titanium oxide film, a zinc-doped tin oxide film, a zinc-doped nickel oxide film, and a zinc-doped aluminum oxide film.

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