Method for designing organic solar cell by using external electric field to regulate charge transfer dynamics

Abstract

The invention discloses an organic solar cell design method based on external electric field regulation and control charge transfer dynamics, and belongs to the technical field of organic photoelectric devices. The core of the invention is to provide a universal design method instead of a single device. The method comprises the following steps: aiming at a selected donor-acceptor material pair, simulating key parameters, namely recombination energy lambda, Gibbs free energy change delta G and a change rule of an electron coupling matrix element VDA in a Marcus theory under different external electric field intensities through quantum chemistry calculation; identifying a dominant regulation factor of an external electric field on the charge transfer rate of the material system; and determining an optimal external electric field intensity window which maximizes the charge separation rate (KCS) and minimizes the charge recombination rate (KCR). According to the method, a direct bridge from microcosmic parameter calculation to macroscopic performance optimization is established for the first time, design and preparation of the high-performance organic solar cell can be accurately and efficiently guided, and the cost and period of traditional'trial and error 'research and development are remarkably reduced.

Description

Technical Field

[0001] This invention relates to the field of organic optoelectronic device technology, and in particular to a method for optimizing the performance of organic solar cells based on precise control of charge transfer dynamics by an external electric field, and a device for implementing this method. Background Technology

[0002] Organic solar cells (OSCs) have attracted much attention due to their low cost, flexibility, and solution-processability; however, their photoelectric conversion efficiency (PCE) remains a key bottleneck restricting their commercial application. Improving efficiency largely depends on efficient charge separation and transport within the active layer, a process constrained by the complex charge transfer dynamics at the donor-acceptor interface.

[0003] Currently, strategies for improving the performance of OSCs mainly focus on new material development, morphology optimization, and device engineering. These methods largely rely on extensive repetitive experimental "trial and error," resulting in long development cycles and high costs. External electric fields, as an external physical stimulus, have been shown to influence molecular energy levels, dipole moments, and electronic coupling, thus providing a new avenue for controlling charge transfer. However, current research largely remains at the level of phenomenological observation, and the systematic influence of external electric fields on key parameters (λ, ΔG, ...) in Marcus theory remains largely unexplored. V DA There is a lack of a clear and universally applicable theoretical framework to guide the design of devices, including how to utilize these influencing principles. Current technology cannot answer the questions of which parameter an external electric field primarily affects for a given material system, or how to determine the optimal electric field strength range.

[0004] Therefore, there is an urgent need in this field for a theoretical guidance method that can accurately predict and optimize the effect of external electric field control based on microscopic mechanisms, in order to replace the traditional trial-and-error mode and achieve targeted and efficient improvement of the performance of organic solar cells. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a design method for organic solar cells that uses an external electric field to regulate charge transfer dynamics. This method combines quantum chemical calculations with Marcus theory to predict the regulation of an external electric field on a specific donor-acceptor system and determine the optimal operating parameters, providing a theoretical basis and practical guide for the rational design of high-performance organic solar cells.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a design method for organic solar cells using external electric field-controlled charge transfer dynamics, comprising the following steps: Step S1: Determine the donor and acceptor materials used in the active layer of the organic solar cell; Step S2: Construct a model system for the interaction between the donor and the acceptor, and set a series of different external electric field conditions; Step S3: Based on quantum chemical calculations, simulate the key parameters of charge transfer dynamics in the model system under different external electric fields. The key parameters include the recombination energy λ, the Gibbs free energy change ΔG, and the electronic coupling matrix element. V DA ; Step S4: Based on the key parameters calculated in Step S3, and using Marcus electron transfer theory, calculate the charge separation rate under different external electric fields. K CS With charge recombination rate K CR ; Step S5: Comparative Analysis K CS and K CR Based on the changing trend of the external electric field, the regulating factor that plays a dominant role in the charge transfer rate is determined, and a selection is made that... K CS / K CR The ratio reaches the optimal range of external electric field strength, which serves as the optimal working range for the donor-acceptor material pair.

[0007] Preferably, in step S5, the dominant regulatory factor is determined in the following way: if K CS and K CR If the trend of change of λ is most similar to the trend of change of λ, then λ is determined to be the dominant factor; if the trend of change of λ is most similar to that of ΔG, then ΔG is determined to be the dominant factor.

[0008] Preferably, the donor material is mCBP and the acceptor material is PO-T2T.

[0009] Preferably, in step S3, for the mCBP:PO-T2T system, the external electric field strength is -7×10⁻⁶. -5 au to 7×10 -5 Within the au range, the recombination energy λ is the dominant regulator of the charge transfer rate, and within this range... K CS It increases with the increase of the external electric field.

[0010] An organic solar cell device obtained by the organic solar cell design method of regulating charge transfer dynamics by the external electric field includes an external electric field application device configured to apply an electric field within the optimal external electric field strength range determined by the method to the active layer of the device.

[0011] Preferably, the external electric field application device includes an electrode pair integrated inside or outside the device, and the direction and intensity of the electric field are dynamically adjusted by programmable power supply control.

[0012] The beneficial effects of this invention are as follows: 1. Creativity and Universality: This invention is the first to propose a "method" that combines microscopic theoretical calculations with macroscopic performance optimization, rather than being limited to a single device structure. It reveals that the dominant control factor of the external electric field may differ for different material systems (e.g., the recombination energy λ in the mCBP:PO-T2T system), which provides a fundamental principle for personalized and precise device design.

[0013] 2. Foresight and guidance: This method can predict the optimal external electric field operating conditions through theoretical simulation before the actual device is fabricated, which greatly reduces the blindness of experiments and the consumption of resources, and shortens the research and development cycle.

[0014] 3. High practicality: This method can guide the development of organic solar cell devices with integrated external electric field application devices, and by adjusting the external electric field, it can keep the device operating in the optimal performance range, significantly improving the actual photoelectric conversion efficiency and application potential of the device. Attached Figure Description

[0015] Figure 1 Molecular structure diagrams of the donor (mCBP) and acceptor (PO-T2T) in Example 1; Figure 2 : The optimized ground-state geometry of the donor-acceptor heterostructure; Figure 3 : A graph showing the effect of the external electric field (Fext) on the recombination energy (λ) in Example 1; Figure 4 : Curves showing the effect of the external electric field (Fext) on the Gibbs free energy changes (ΔGCS and ΔGCR) in Example 1; Figure 5 Changes in the electronic coupling matrix elements in Example 1; Figure 6 : The curve showing the effect of the external electric field (Fext) on the charge separation rate (KCS) in Example 1. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but the scope of protection of the present invention is not limited thereto.

[0017] Example 1: Performance optimization method applied to the mCBP:PO-T2T system

[0018] This embodiment uses mCBP as the donor material and PO-T2T as the acceptor material, with the molecular structure as follows: Figure 1 Taking the aforementioned system as an example, the specific implementation process of the present invention will be demonstrated. It should be noted that this embodiment is intended to illustrate the feasibility of the method, and its calculation data and conclusions are directly derived from the theoretical research results in Appendix 1, and do not involve unpublished experimental data that may cause conflict.

[0019] Steps S1 & S2: System Construction and Condition Setting

[0020] The research subject was identified as the mCBP:PO-T2T receptor pair. A computational model of their interaction was constructed, such as... Figure 2 As shown, the optimized ground-state geometry of the donor-acceptor heterojunction is illustrated, and an external electric field is set ( F ext The simulation range is from -7×10 -5 au to +7×10 -5 au.

[0021] Step S3: Calculation and simulation of key parameters

[0022] Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) were used in quantum chemical calculation software such as Gaussian 16 to calculate the recombination energy λ and Gibbs free energy change ΔG of the system under different external electric fields. CS , ΔG CR and electronic coupling matrix element V DA .

[0023] The calculation results are as follows Figure 3 As shown, the recombination energy λ increases with the increase of the external electric field strength.

[0024] The calculation results are as follows Figure 4 As shown, ΔG CS The negative value of ΔG decreases as the external electric field increases, meaning its absolute value decreases, while ΔG CR The changes were minimal.

[0025] The calculation results are as follows Figure 5 As shown, it indicates V DA The variation is minimal within this electric field range.

[0026] Steps S4 & S5: Dynamic Analysis and Optimal Window Determination

[0027] Substituting the above parameters into Marcus formula (1), we obtain the following calculation: K CS The curves that vary with the external electric field, such as Figure 5 As shown. K CSThe value increases with increasing electric field.

[0028] (1)

[0029] Dominant factor determination: comparison Figure 3 , Figure 4 , Figure 5 and Figure 6 It can be observed that, K CS The changing trend of is highly consistent with the changing trend of λ, and with ΔG CS and V DA The correlation is relatively weak. Therefore, for the mCBP:PO-T2T system, the recombination energy (λ) is determined to be the dominant factor in the external electric field regulating the charge transfer rate.

[0030] Optimal window determination: within the simulation range, K CS Continued growth, and K CR far below K CS (Six orders of magnitude lower). Therefore, it can be determined that for this system, at -7 × 10⁻⁶... -5 au to 7×10 -5 Within the positive electric field range of au, the performance is continuously optimized, and the optimal range can be located at the high-intensity end (e.g., 7×10). -5 (near au).

[0031] Example 2: Device integrating an external electric field device

[0032] Based on the optimization conclusions derived in Example 1, an organic solar cell device can be designed. This device integrates a pair of transparent parallel plate electrodes as external electric field application devices, located on opposite sides of the active layer, based on a conventional structure (anode / active layer (mCBP:PO-T2T) / cathode). These electrodes are connected to a programmable power supply, and the optimal electric field strength (e.g., 7 × 10⁻⁶) determined in Example 1 can be applied. -5 An external electric field is applied to the device (the voltage value corresponding to au) so that the device operates in the theoretically predicted optimal performance state.

Claims

1. A method for designing organic solar cells using external electric field-controlled charge transfer dynamics, characterized in that, Includes the following steps: Step S1: Determine the donor and acceptor materials used in the active layer of the organic solar cell; Step S2: Construct a model system for the interaction between the donor and the acceptor, and set a series of different external electric field conditions; Step S3: Based on quantum chemical calculations, simulate the key parameters of charge transfer dynamics in the model system under different external electric fields. The key parameters include the recombination energy λ, the Gibbs free energy change ΔG, and the electronic coupling matrix element. V DA ; Step S4: Based on the key parameters calculated in Step S3, and using Marcus electron transfer theory, calculate the charge separation rate under different external electric fields. K CS With charge recombination rate K CR ; Step S5: Comparative Analysis K CS and K CR Based on the changing trend of the external electric field, the controlling factor that plays a dominant role in the charge transfer rate is determined, and a selection is made to make the rate of charge transfer... K CS / K CR The ratio reaches the optimal range of external electric field strength, which serves as the optimal working range for the donor-acceptor material pair.

2. The method for designing organic solar cells with external electric field-controlled charge transfer dynamics according to claim 1, characterized in that, In step S5, the dominant regulatory factor is determined in the following way: if K CS and K CR If the trend of change of λ is most similar to the trend of change of λ, then λ is determined to be the dominant factor. If the trend of change of ΔG is most similar to that of ΔG, then ΔG is determined to be the dominant factor.

3. The method for designing organic solar cells with external electric field-controlled charge transfer dynamics according to claim 1, characterized in that, The donor material is mCBP, and the acceptor material is PO-T2T.

4. The method for designing organic solar cells with external electric field-controlled charge transfer dynamics according to claim 1, characterized in that, In step S3, for the mCBP:PO-T2T system, the external electric field strength is -7×10⁻⁶. -5 au to 7×10 -5 Within the au range, the recombination energy λ is the dominant regulator of the charge transfer rate, and within this range... K CS It increases with the increase of the external electric field.

5. An organic solar cell device obtained by using the organic solar cell design method of external electric field-controlled charge transfer dynamics as described in any one of claims 1-4, characterized in that, The organic solar cell device includes an external electric field application device configured to apply an electric field to the active layer of the device within an optimal external electric field strength range determined by the method of any one of claims 1 to 4.

6. The organic solar cell device according to claim 5, characterized in that, The external electric field application device includes an electrode pair integrated inside or outside the device, and the direction and intensity of the electric field are dynamically adjusted by programmable power supply control.

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