A semi-transparent organic solar cell with temperature control function and a preparation method thereof

Abstract

The application discloses a semi-transparent organic solar cell with a temperature control function and a preparation method thereof, and belongs to the technical field of semiconductor organic solar cells. The semi-transparent organic solar cell is composed of an ITO glass substrate, a PEDOT:PSS hole transport layer, a PM6:Y6:PCB71M:Au NPs photoelectric conversion layer, a PNDIT-F3N electron transport layer and a Cr / Ag composite electrode. In the application, chromium is introduced as a seed layer to change the wetting property of metal silver on the surface of the device, to induce the silver island to change from longitudinal growth to horizontal growth, and to more easily generate a continuous metal film. In this way, the good light transmission of the metal film is ensured, the conductive performance of the metal film is improved, and the square resistance is reduced. The use of the Cr / Ag composite electrode forms a Bragg reflector to reflect light in the near-infrared range, so that part of the light originally transmitted through the photoelectric conversion layer is reflected back to be absorbed and utilized again, thereby increasing the conversion efficiency of the battery and realizing the function of controlling the temperature of the device.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor organic solar cell technology, specifically relating to a semi-transparent organic solar cell with temperature control function and its preparation method. Background Technology

[0002] Organic solar cells (OSCs), as a type of thin-film solar cell, have experienced rapid development in recent years due to their unique advantages. Among them, semi-transparent organic solar cells (ST-OSCs) are one of the most representative applications in the OSC field, showing broad application prospects in building exterior glass, agricultural greenhouses, and automotive coatings. With the continuous development of narrow bandgap semiconductor materials, the usable spectral range of organic solar cells has been further broadened into the infrared spectrum, and their efficiency has also improved. Simultaneously, researchers have begun to study semi-transparent organic solar cells, which can not only generate electricity but also control the transmitted light. An ideal semi-transparent solar cell should have high ultraviolet and near-infrared photon utilization while maintaining a proper balance between absorption and transparency in the visible light range.

[0003] Transparent electrodes, possessing high transmittance and high conductivity, are a crucial component of semi-transparent optoelectronic devices and have garnered significant attention. Currently, indium tin oxide (ITO) glass sputtered onto glass is the standard transparent electrode, exhibiting excellent light transmittance and conductivity. However, its fabrication process disrupts the underlying structure during top electrode preparation, making ultrathin metal electrodes fabricated using thermal vacuum evaporation the primary top electrode for ST-OSCs. However, research has revealed that the evaporated metal exhibits an island-like growth pattern (Volmer-Weber) on the device surface. Before the film reaches a certain thickness, the metal islands are discontinuous or lack continuity, leading to a rough film and poor conductivity. To overcome this drawback, researchers have introduced a seed layer method to fabricate composite electrodes.

[0004] Chromium is a metal with good stability and conductivity. Introducing metallic chromium as a seed layer alters the surface tension of the device, improving the wettability of silver and inducing silver to grow along a two-dimensional direction on the device surface, resulting in a better continuous film formation. Simultaneously, the combination of chromium (Cr) and silver (Ag) also forms a Bragg reflector. When some light that has passed through the photoelectric conversion layer reaches the electrode, the Cr / Ag composite electrode reflects near-infrared light back. Combined with a narrow-bandgap photoelectric conversion material, the reflected light is then absorbed and converted again.

[0005] Surface plasmon resonance (SPR) refers to the plasmon resonance phenomenon that occurs around nanomaterials when the incident light frequency is close to the electron density wave frequency. This resonance effect enhances the local electromagnetic field, thereby improving photon capture rate and electron transport capability. Noble metal nanomaterials such as silver and gold are commonly used to make the resonance occur in the visible light range. However, unlike other materials and shapes of nanomaterials, the presence of gold nanorods shifts the resonance peak towards the near-infrared direction. By adjusting the ratio of the diameter to the length of the gold nanorods, the absorption wavelength can be continuously tunable in the near-infrared band. Solutions of gold nanorods with absorption peaks greater than 750 nm are almost transparent and colorless, demonstrating that doping with appropriately sized gold nanorods not only improves device performance but also does not affect the visible light transmittance of the device.

[0006] Existing technologies using vacuum evaporation to fabricate electrodes exhibit a volmer-weber growth pattern. When the wettability between the deposited metal and the substrate is weak, the metal atoms reaching the substrate tend to bond to themselves rather than to the substrate atoms. Consequently, the evaporated metal initially forms isolated atomic nuclei on the dielectric surface, eventually forming metal islands. With further evaporation, the edges of these islands begin to contact, forming a continuous conductive layer. This results in poor conductivity of the metal film within a certain thickness. Increasing the electrode thickness to maintain conductivity, however, affects the electrode's light transmittance. Simultaneously, to ensure the light transmittance of ST-OSCs, the cell's layers must be made as thin as possible; however, thinning the photoelectric conversion layer leads to significant light loss.

[0007] Currently, fabricating semi-transparent organic solar cells using Cr / Ag composite electrodes is still a novel approach. The combination of electrodes with infrared modulation capabilities and gold nanorods that enhance near-infrared absorption improves both the photoelectric conversion efficiency of the cell and enables light control. Reducing the transmission of near-infrared light helps suppress the internal temperature rise caused by absorbing solar heat, thus achieving energy conservation and environmental protection. Summary of the Invention

[0008] The purpose of this invention is to provide a semi-transparent organic solar cell with temperature control function and its preparation method.

[0009] The ST-OSCs of this invention are composed, in sequence according to the direction of sunlight incidence, an ITO glass substrate, a PEDOT:PSS hole transport layer, a PM6:Y6:PCB71M:Au NPs photoelectric conversion layer prepared by sol-gel method, a PNDIT-F3N electron transport layer, and a Cr / Ag composite electrode, wherein ITO is the bottom electrode and Cr / Ag is the top electrode. The device structure is as follows: Figure 1 As shown.

[0010] The method for preparing a semi-transparent organic solar cell (ST-OSCs) with temperature control function according to the present invention comprises the following steps:

[0011] 1) Substrate cleaning

[0012] The ITO glass substrate was ultrasonically cleaned in acetone, ethanol and deionized water for 10-15 minutes in sequence, and then dried with nitrogen; then it was treated in an ultraviolet ozone cleaner for 10-20 minutes.

[0013] 2) Fabrication of a hole transport layer

[0014] The purchased aqueous solution of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonate (PEDOT:PSS) was spin-coated onto a substrate treated with UV ozone using a static spin-coating method (the solution was first evenly spread on a stationary substrate, and then a spin coater was turned on at high speed to prepare a thin film). The spin-coating speed was 3000-5000 rpm and the spin-coating time was 20-40 seconds. Then, it was annealed at 140-160℃ for 10-20 minutes to obtain a PEDOT:PSS hole transport layer with a thickness of 30-50 nm.

[0015] 3) Fabrication of photoelectric conversion layer

[0016] Purchase PM6, Y6, PCB 71 M and Au NPs (gold nanorods) were dissolved in chloroform to obtain a blended solution with a total concentration of 15–20 mg / mL. PM6, Y6, and PCB were also present. 71 The weight ratio of M is 1:1.1:0.2, PM6, Y6, PCB 71 The doping concentration of Au NPs in M ​​and gold nanorods (Au NPs) is 0.5wt% to 1.5wt%. The blend solution is spin-coated onto the hole transport layer by dynamic spin coating (first turning on the spin coater, then dropping the solution onto the substrate at high speed to prepare a thin film), with a spin coating speed of 3000 to 4000 rpm and a spin coating time of 15 to 30 seconds. Then, it is treated under vacuum for 4 to 8 minutes to remove residual solvent, and then thermally annealed at 85 to 95 °C for 4 to 8 minutes to obtain a photoelectric conversion layer with a thickness of 100 to 150 nm.

[0017] 4) Fabrication of electron transport layer

[0018] The purchased PNDIT-F3NT was dissolved in methanol to obtain a solution with a concentration of 0.5-1.0 mg / mL. Then, it was spin-coated onto the photoelectric conversion layer by dynamic spin coating at a speed of 1000-2000 rpm and a spin coating time of 15-30 seconds to obtain a PNDIT-F3NT electron transport layer with a thickness of 30-40 nm.

[0019] 5) Deposition of Cr / Ag composite electrode

[0020] Electrodes were fabricated using thermal vacuum deposition. The device obtained in step 4) was placed in a vacuum chamber and evacuated to a vacuum level of 5.0 × 10⁻⁶. -4 ~9.0×10 -4 Pa; then Cr and Ag are deposited sequentially, with Cr deposition rate of 0.12-0.14 nm / s and deposition thickness of 3-7 nm; Ag deposition rate of 0.3-0.34 nm / s and deposition thickness of 15-35 nm; finally, a semi-transparent organic solar cell with temperature control function as described in this invention is obtained.

[0021] This invention uses ITO glass as a substrate and gold nanorods (Au NPs, 10 nm in diameter and 30 nm to 50 nm in length) doped with PM6, Y6, and PCB. 71 M represents the photoelectric conversion layer, and a semi-transparent organic solar cell (ST-OSC) is fabricated using a Cr / Ag composite electrode as the top electrode. This invention introduces chromium as a seed layer to alter the wettability of metallic silver on the device surface, inducing silver islands to grow laterally instead of vertically, making it easier to form a continuous metal thin film. This ensures good light transmittance of the metal thin film while improving its conductivity and reducing sheet resistance. Furthermore, the use of the Cr / Ag composite electrode forms a Bragg reflector that reflects light in the near-infrared range, causing some of the light that originally passed through the photoelectric conversion layer to be reflected back and absorbed again, thereby increasing the cell conversion efficiency. In this invention, the Cr / Ag composite electrode with infrared reflection function, combined with Au NPs (gold nanorods) that generate surface plasmon resonance, improves the device's fill factor (FF), photoelectric conversion efficiency (PCE), and short-circuit current (J / L). SC ), open circuit voltage (V) OC While improving performance, it reduces the transmission of near-infrared light, thereby lowering the internal temperature of the battery and effectively suppressing near-infrared light. The device described in this invention not only generates electricity but also controls temperature (e.g.,...). Figure 5 (As shown).

[0022] Narrow-bandgap semiconductor organic materials inherently possess excellent absorption capabilities in the near-infrared range. Combining them with nanomaterials (Au NPs) whose surface plasmon resonance absorption wavelengths are close to these wavelengths can further enhance device performance. When light is incident on the battery, the absorption capacity is limited because the photoelectric conversion layer of the organic material is thin, and the light travels in a straight line with a short path. By doping with nanomaterials, surface plasmon resonance significantly increases the material's ability to scatter light, expanding the direction and path of light propagation. Simultaneously, the resonance effect enhances the material's ability to capture photons, thereby improving the light absorption of the photoelectric conversion layer. The use of a semi-transparent electrode for infrared modulation and gold nanorods that enhance the near-infrared light absorption of the photoelectric conversion layer gives the battery a strong ability to suppress near-infrared light, and under certain conditions, it can also control the temperature on the other side of the battery. Figure 5 As shown, the unoptimized basic device (Device A, without the seed layer of chromium and gold nanomaterials) and the present invention (Device B, with chromium as the seed layer and doped with gold nanorods) were placed on a sunlight simulator for comparison, and the device temperature was measured using a handheld thermal imager. The final test results showed that the device temperature decreased from 39.7℃ to 35.0℃. Attached Figure Description

[0023] Figure 1 : A schematic diagram of the structure of the device described in this invention;

[0024] Figure 2 The current-voltage characteristic curves of the device (Cr layer thicknesses of 0 nm, 3 nm, and 5 nm, and silver thickness of 20 nm) prepared in Example 1 of this invention are shown.

[0025] Figure 3 External quantum efficiency (EQE) curves of devices (Cr layer thicknesses of 0 nm, 3 nm, and 5 nm, and silver thickness of 20 nm) prepared in Example 1 of this invention.

[0026] Figure 4 The transmittance curves of the Cr / Ag composite electrode (Cr layer thickness is 5nm, Ag layer thickness is 20nm) and the Ag electrode (thicknesses are 20nm and 25nm respectively) described in Example 1 of this invention, and the sheet resistance (resistance value of material per unit area and unit thickness) data measured by a handheld four-probe sheet resistance meter.

[0027] Figure 5 The unoptimized basic device (Device A, without the seed layer of chromium and gold nanomaterials) and the device of the present invention (Device B, with chromium as the seed layer and doped with gold nanorods) were placed on a sunlight simulator for comparison, and the device temperature was measured by a handheld thermal imager.

[0028] like Figure 1 As shown, the ST-OSCs of this invention, arranged sequentially according to the direction of sunlight incidence, consist of an ITO substrate (ITO glass substrate) attached to glass, a PEDOT:PSS hole transport layer, a PM6:Y6:PCB71M:Au NPs photoelectric conversion layer prepared by sol-gel method, a PNDIT-F3N electron transport layer, and a Cr / Ag composite electrode, wherein ITO is the bottom electrode and Cr / Ag is the top electrode. When sunlight enters from the glass side, some of the near-infrared light is reflected back when it passes through the photoelectric conversion layer and reaches the composite electrode. The reflected near-infrared light passes through the photoelectric conversion layer again and is absorbed and utilized, thereby improving the device performance.

[0029] like Figure 2 As shown, with the continuous increase of Cr, the device performance gradually improves, and the fill factor (FF, the ratio of the product of current and voltage when the battery has maximum output power to the product of short-circuit current and open-circuit voltage) increases from 65.9% to 72.2%.

[0030] like Figure 3 As shown, by testing the external quantum efficiency (EQE, the ratio of the number of electrons collected to the number of incident photons) of the device, it can be observed that as the thickness of Cr increases, the utilization efficiency of the device in the near-infrared band also increases (the number of electrons generated under the same incident light increases).

[0031] like Figure 4 As shown, when the electrode thickness is the same (Cr layer thickness is 5nm, Ag layer thickness is 20nm and Ag electrode thickness is 25nm), the light transmittance of the composite electrode is better than that of the pure silver electrode. At the same time, by comparing the sheet resistance, it can be concluded that the composite electrode has the best conductivity.

[0032] like Figure 5 As shown, the temperature of the device decreased from 39.7℃ (Device A) to 35.0℃ (Device B). Detailed Implementation

[0033] Example 1

[0034] 1) Substrate cleaning

[0035] The ITO glass substrate was ultrasonically cleaned in acetone, ethanol and deionized water for 15 minutes in sequence, and then dried with nitrogen; then it was treated in an ultraviolet ozone cleaner for 15 minutes.

[0036] 2) Fabrication of a hole transport layer

[0037] PEDOT:PSS was coated onto a UV-ozone-treated substrate using a static spin-coating method at a speed of 4000 rpm for 30 seconds, followed by annealing at 150°C for 15 minutes on a hot plate. The resulting hole transport layer had a thickness of 30 nm.

[0038] 3) Fabrication of the photoelectric conversion layer (i.e., the active layer)

[0039] PM6, Y6, PCB71M, and Au NPs were dissolved in chloroform to obtain a blend solution with a total concentration of 16.4 mg / mL. The weight ratio of PM6, Y6, and PCB71M was 1:1.1:0.2, and the doping concentration of Au NPs in the PM6, Y6, PCB71M, and Au NPs was 1.0 wt%. The blend solution was spin-coated onto the hole transport layer at 3500 rpm for 20 seconds. Vacuum treatment for 5 minutes was performed to remove residual solvent, followed by thermal annealing of the active layer at 90°C for 5 minutes. The resulting photoelectric conversion layer had a thickness of 100 nm.

[0040] 4) Fabrication of electron transport layer

[0041] PNDIT-F3NT solution (dissolved in methanol at a concentration of 0.5 mg / mL) was dynamically spin-coated onto the annealed active layer at 1500 rpm for 20 seconds. No annealing was required after spin-coating, resulting in an electron transport layer with a thickness of 30 nm.

[0042] 5) Deposition of Cr / Ag composite electrode

[0043] Electrodes were fabricated using thermal vacuum deposition. After spin-coating the electron layer, the device was placed in a vacuum chamber and evacuated to a vacuum level of 7.0 × 10⁻⁶. -4 Pa. Cr is deposited at a rate of 0.13 nm / s to deposit 0, 3, or 5 nm, and Ag is deposited at a rate of 0.32 nm / s to deposit 20 nm; finally, a semi-transparent organic solar cell with temperature control function as described in this invention is obtained.

Claims

1. A method for preparing a semi-transparent organic solar cell with temperature control function, comprising the following steps: 1) Substrate cleaning The ITO glass substrate was ultrasonically cleaned in acetone, ethanol and deionized water for 10-15 minutes in sequence, and then dried with nitrogen. Then place it in an ultraviolet ozone cleaner for 10-20 minutes; 2) Fabrication of a hole transport layer An aqueous solution of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonate was spin-coated onto a substrate treated with ultraviolet ozone by static spin coating; then annealed at 140–160 °C for 10–20 minutes to obtain a hole transport layer. 3) Fabrication of photoelectric conversion layer PM6, Y6, PCB 71 M and Au NPs were dissolved in chloroform to obtain a blended solution with a total concentration of 15–20 mg / mL. PM6, Y6, and PCB were also present. 71 The weight ratio of M is 1:1.1:0.2; PM6, Y6, PCB 71 In M and Au NPs, the doping concentration of Au NPs is 0.5wt% to 1.5wt%. The blend solution is spin-coated onto the hole transport layer by dynamic spin coating. Then, it is treated under vacuum for 4 to 8 minutes to remove residual solvent, and then thermally annealed at 85 to 95°C for 4 to 8 minutes to obtain the photoelectric conversion layer. 4) Fabrication of electron transport layer PNDIT-F3NT was dissolved in methanol to obtain a solution with a concentration of 0.5–1.0 mg / mL, and then spin-coated onto the photoelectric conversion layer by dynamic spin-coating to obtain the PNDIT-F3NT electron transport layer. 5) Deposition of Cr / Ag composite electrode Electrodes were fabricated using thermal vacuum deposition. The device obtained in step 4) was placed in a vacuum chamber and evacuated to a vacuum level of 5.0 × 10⁻⁶. -4 ~9.0×10 -4 Pa; then Cr and Ag are deposited sequentially to finally obtain a semi-transparent organic solar cell with temperature control function.

2. The method for preparing a semi-transparent organic solar cell with temperature control function as described in claim 1, characterized in that: In step 2), the spin coating speed is 3000–5000 rpm and the spin coating time is 20–40 seconds; in step 3), the spin coating speed is 3000–4000 rpm and the spin coating time is 15–30 seconds; in step 4), the spin coating speed is 1000–2000 rpm and the spin coating time is 15–30 seconds; in step 5), the Cr deposition rate is 0.12–0.14 nm / s and the Ag deposition rate is 0.3–0.34 nm / s.

3. The method for preparing a semi-transparent organic solar cell with temperature control function as described in claim 1, characterized in that: The hole transport layer has a thickness of 30–50 nm, the photoelectric conversion layer has a thickness of 100–150 nm, the PNDIT-F3NT electron transport layer has a thickness of 30–40 nm, the Cr deposition thickness is 3–7 nm, and the Ag deposition thickness is 15–35 nm.

4. A semi-transparent organic solar cell with temperature control function, characterized in that: It is prepared by the method described in any one of claims 1 to 3.

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