Abstract
To enhance the photoelectric conversion efficiency of smart energy acquisition systems in low-carbon parks, this study presents the development of solar panel cells with high power conversion efficiency. These cells are prepared using 1,3-dibromo-5,5-dimethylhydantoin (DBH) and diketone isoindole as donor materials, combined with non-fullerene Y6-BO and PTIC as acceptor materials. The optimal ratio, voltammetry characteristics, and carrier transfer properties of these materials are thoroughly tested. The results indicate that when Y6-BO is used as the acceptor material, the solar panel cells exhibit a higher photoelectric conversion efficiency, reaching an optimal energy conversion efficiency of 15.23%, which is 3.86% higher than when PTIC is used. This study lays a theoretical foundation for the effective conversion of photovoltaic energy in new solar panel smart energy acquisition systems in low-carbon parks.
1. Introduction
In low-carbon parks, solar energy is a primary source of electricity, with solar solar panel playing a crucial role. However, due to technological limitations, the photoelectric conversion efficiency of solar panel cells remains relatively low. Researchers and experts are striving to improve this efficiency to enhance the utilization of solar energy.
1.1 Background
Solar panel convert sunlight into electrical energy through photovoltaic effects. The efficiency of this conversion process directly affects the amount of energy that can be generated from a given area of solar panel. Currently, various materials and technologies are being explored to enhance the photoelectric conversion efficiency of solar panel cells.
1.2 Motivation
By improving the photoelectric conversion efficiency of solar panel cells, we can increase the amount of electrical energy generated from a given area of solar panel. This not only reduces the cost of solar energy but also promotes the wider application of solar energy in various fields.
1.3 Research Objectives
The primary objectives of this study are to:
- Develop high-efficiency solar panel cells using novel materials.
- Optimize the material ratio and film thickness to achieve the highest possible photoelectric conversion efficiency.
- Investigate the voltammetry characteristics and carrier transfer properties of the developed solar panel cells.
2. Materials and Methods
2.1 Materials
The materials used in this study include:
- Solvents: Hexane, Dichloromethane, Chloroform, Toluene, Ether, N,N-Dimethylformamide, etc.
- Reactants: 1,3-Dibromo-5,5-dimethylhydantoin (DBH), Diketone isoindole, N-Bromosuccinimide (NBS), Triphenylphosphine palladium, etc.
- Substrates: Indium tin oxide (ITO) glass.
- Other materials: Silver for electrode deposition, PEDOT/PSS for hole transport layer, etc.
2.2 Equipment
The equipment used in this study includes:
- Spectrophotometer: Shimadzu UV-1800 for UV-Vis absorption spectroscopy.
- Step Profiler: D-120 for film thickness measurement.
- Electrochemical Analyzer: CHI620D for cyclic voltammetry.
- Spin Coater: For uniform coating of materials.
- Evaporator: For silver electrode deposition.
2.3 Methods
2.3.1 Preparation of Donor Material
The donor material, denoted as A6, is synthesized through a series of chemical reactions:
- Synthesis of A1: A mixture of monofluoromonoalkoxy, tributyl(3-thienyl)tin, triphenylphosphine palladium, and anhydrous dichloromethane is heated at 130°C for 12 hours, followed by evaporation and extraction with dichloromethane.
- Synthesis of A2: A1 is reacted with anhydrous ferric chloride in anhydrous dichloromethane at room temperature, followed by filtration and evaporation. The product is extracted with n-hexane.
- Synthesis of A3: A2 is reacted with N-Bromosuccinimide (NBS) and concentrated sulfuric acid in chloroform, followed by the addition of methanol and water. The product is filtered and extracted.
- Synthesis of A4: A3 is reacted with tributyl(4-(2-butyloctyl)thiophen-2-yl)stannane, triphenylphosphine palladium, toluene, and N,N-dimethylformamide at 112°C for 12 hours. The product is extracted with polyethylene and dichloromethane.
- Synthesis of A5: A4 is reacted with NBS in chloroform, followed by the addition of methanol. The product is filtered and extracted with a mixture of polyethylene and dichloromethane.
- Synthesis of A6: A5 is reacted with 2-ethylhexyloxybenzo[1,2-b:4,5-b’]dithiophene (FBDT-Sn), tris(dibenzylideneacetone)dipalladium, and tri(o-tolyl)phosphine in toluene at 112°C for 16 hours. The product is extracted with a specific ratio of dichloromethane, carbon fluoride, and chloroform.
2.3.2 Preparation of Solar Panel Cells
- Substrate Cleaning: ITO glass substrates are cleaned sequentially in deionized water, acetone, and isopropanol using an ultrasonic cleaner, followed by ozone-UV treatment.
- Spin Coating: A PEDOT/PSS layer is spin-coated onto the cleaned ITO glass and annealed at 150°C. The donor material A6 is mixed with either Y6-BO or PTIC at a specific ratio, and the mixture is spin-coated onto the PEDOT/PSS layer and annealed again. Finally, a PDIN layer is spin-coated from a MeOH/AcOH solution.
- Electrode Deposition: Silver electrodes are deposited onto the spin-coated films under high vacuum conditions.
3. Results and Analysis
3.1 Material Characterization
3.1.1 Absorption Spectra
The UV-Vis absorption spectra of A6 in solution and film states are shown in Figure 1.
Figure 1: Absorption Spectra of A6
The absorption peaks of A6 in both solution and film states are observed at 532 nm and 568 nm, respectively, indicating strong aggregation. The optical bandgap of A6, calculated from the absorption edge in the film state, is 2.10 eV, confirming its wide bandgap nature.
3.1.2 Electrochemical Properties
The cyclic voltammetry curves and energy level diagram of A6 are shown in Figure 2.
Figure 2: Cyclic Voltammetry and Energy Level Diagram of A6
The oxidation and reduction potentials of A6 are 0.7 V and -1.98 V, respectively. The HOMO and LUMO energy levels are calculated to be -5.5 eV and -2.8 eV, respectively. The electrochemical bandgap and effective LUMO energy level are 2.69 eV and -3.46 eV, respectively. The introduction of diketone isoindole is found to lower the orbital energy levels of A6.
3.2 Solar Panel Cell Performance
3.2.1 Optimal Material Ratio and Film Thickness
To determine the optimal conditions for solar panel cell fabrication, various ratios of donor to acceptor materials and film thicknesses were tested. The results are summarized in Table 1.
Table 1: Energy Conversion Efficiency of solar Panel
| Donor:Acceptor Ratio | Film Thickness (nm) | Energy Conversion Efficiency (%) |
|---|---|---|
| 1:1 | 80 | 11.22 |
| 1:1.5 | 100 | 15.23 |
| 1:2 | 120 | 13.66 |
| 1:1 | 100 | 13.87 |
| 1:1.5 | 120 | 15.23 |
| 1:2 | 80 | 13.39 |
| 1:1.5 | 80 | 9.38 |
| 1:2 | 100 | 8.45 |
| 1:1 | 120 | 11.37 |
| 1:1.5 | (Control) | 7.22 |
| 1:2 | (Control) | 11.37 |
| 1:1.5 | (Control) | 9.22 |
The highest energy conversion efficiency of 15.23% is achieved when the donor-to-acceptor ratio is 1:1.5 and the film thickness is 100 nm.
3.2.2 Voltammetry Characteristics
The current density-voltage (J-V) characteristics of the solar panel cells prepared under optimal conditions are shown in Figure 3.
Figure 3: J-V Characteristics of Solar Panel Cells
The solar panel cell prepared with A6 and Y6-BO exhibits a higher power conversion efficiency compared to the cell prepared with A6 and PTIC, with an increase of 4.38 mA/cm² in current density. This is attributed to the broader absorption range of Y6-BO.
3.2.3 Carrier Transport Properties
The carrier mobilities of the pure and mixed films are summarized in Table 2.
Table 2: Carrier Mobilities of Pure and Mixed Films
| Material | Carrier Mobility (cm²/(V·s)) | Charge Transport Rate (cm²/(V·s)) |
|---|---|---|
| A6 | 5.80 × 10⁻⁴ | – |
| A6:Y6-BO (1:1.2) | 2.40 × 10⁻⁴ | 1.04 × 10⁻⁴ |
| A6:PTIC (1:1.2) | 1.83 × 10⁻⁴ | 0.84 × 10⁻⁴ |
The A6:Y6-BO mixed film exhibits higher carrier mobility and charge transport rate compared to the A6:PTIC mixed film, indicating better charge transport properties.
3.2.4 Exciton Dissociation and Bimolecular Recombination
The exciton dissociation and bimolecular recombination characteristics of the solar panel cells are shown in Figure 4.
Figure 4: Exciton Dissociation and Bimolecular Recombination of Solar Panel Cells
(a) The short-circuit current reaches saturation at an effective voltage of approximately 3 V, with exciton dissociation efficiencies of 96.22% and 92.38% for A6:Y6-BO and A6:PTIC, respectively.
(b) The power law exponent values are 0.9750 and 0.9432 for A6:Y6-BO and A6:PTIC, respectively, indicating less charge recombination in A6:Y6-BO cells.
3.3 Discussion
The results demonstrate that the use of Y6-BO as the acceptor material, combined with the donor material A6, results in solar panel cells with higher photoelectric conversion efficiency compared to cells using PTIC as the acceptor material. This is attributed to the broader absorption range and better charge transport properties of Y6-BO.
4. Conclusion
4.1 Key Findings
- Material Properties: The synthesized donor material A6 exhibits wide bandgap properties with an optical bandgap of 2.10 eV and an electrochemical bandgap of 2.69 eV.
- Optimal Conditions: The optimal energy conversion efficiency of 15.23% is achieved when the donor-to-acceptor ratio is 1:1.5 and the film thickness is 100 nm.
- Performance Comparison: Solar panel cells prepared with A6 and Y6-BO exhibit higher power conversion efficiency, current density, carrier mobility, and charge transport rate compared to cells prepared with A6 and PTIC.
4.2 Implications
The development of high-efficiency solar panel cells using novel materials has important implications for the utilization of solar energy. By improving the photoelectric conversion efficiency, the cost of solar energy can be reduced, promoting its wider application in various fields.
4.3 Future Work
Future research could focus on:
- Material Optimization: Further optimization of the donor and acceptor materials to achieve even higher photoelectric conversion efficiencies.
- Scalability: Investigating the scalability of the fabrication process for large-scale production of high-efficiency solar panel cells.
- System Integration: Developing intelligent acquisition systems that can efficiently collect and utilize the energy generated by high-efficiency solar panel cells in low-carbon parks.