Micromolecule organic solar cell device and method for optimizing performance of micromolecule organic solar cell device based on external electric field regulation interface electronic coupling

Abstract

The invention discloses a small-molecule organic solar cell device and a method for regulating interface electronic coupling based on an external electric field to optimize performance of the small-molecule organic solar cell device. The small-molecule organic solar cell device comprises an active layer, an electrode and an external electric field applying device, wherein the active layer is composed of a donor material MTDATA and an acceptor material TmPyPB. By adjusting the direction and the intensity of an electric field within an external electric field intensity range of-10 * 10 <-5 > au to 10 * 10 <-5 > au, accurate regulation and control of an electronic coupling matrix element are realized, so that the charge separation rate and the charge recombination rate are optimized, and the photoelectric conversion efficiency of the battery is improved. According to the invention, an external electric field regulation and control mechanism is combined with a specific small molecule material system for the first time, a simple, efficient and integratable performance optimization scheme is provided, and the method is suitable for flexible and wearable photoelectric devices.

Description

Technical Field

[0001] This invention belongs to the field of organic optoelectronic device technology, specifically relating to a small molecule organic solar cell device and its optimization method that uses an external electric field to regulate the charge transfer rate. Background Technology

[0002] Organic solar cells (OSCs) have become an important research direction for next-generation photovoltaic technology due to their advantages such as low cost, simple fabrication process, and flexibility. However, their photoelectric conversion efficiency (PCE) is still generally lower than that of traditional silicon-based cells. One of the main bottlenecks is the insufficient charge transfer rate, which leads to high exciton recombination rate and low carrier extraction efficiency.

[0003] Currently, the main methods for improving the performance of organic solar cells include: 1) material modification, such as synthesizing novel donor / acceptor materials; 2) interface engineering, such as introducing buffer layers; and 3) device structure optimization, such as heterojunction design. While these methods have some effect, they are often complex in process, costly, and difficult to dynamically control.

[0004] External electric fields, as a type of external physical field, have been shown to influence molecular energy levels, electronic coupling, and charge transfer dynamics. Existing research indicates that external electric fields can modulate charge transport behavior in organic semiconductors, but most studies are limited to theoretical simulations, lacking practical device integration schemes for small molecule systems, and failing to clarify the regulation mechanisms and optimization windows of various parameters of the charge transfer rate (such as electronic coupling matrix elements, recombination energy, and Gibbs free energy) by external electric fields. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to provide a small-molecule organic solar cell device and a method for optimizing its performance based on external electric field modulation of interfacial electronic coupling. The method of the present invention is simple, efficient, and can be controlled in real time, thereby overcoming the efficiency bottleneck of organic solar cells.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: a small molecule organic solar cell device, comprising an active layer, electrodes, and an external electric field application device; the active layer is made of a mixture of donor and acceptor materials; the electrodes consist of a cathode and an anode; the external electric field application device includes a pair of negative plate electrodes, a positive plate electrode, and an external power supply; with the active layer as the center, a negative plate electrode, a hole transport layer, and a cathode are sequentially arranged on one side of the active layer, and a positive plate electrode, an electron transport layer, and an anode are sequentially arranged on the other side of the active layer; the positive and negative plate electrodes are respectively connected to the positive and negative terminals of the external power supply.

[0007] Furthermore, the donor material is 1,3-bis(9H-carbazole-9-yl)benzene (MTDATA), and the acceptor material is 1,3,5-tris(4-pyridin-3-ylphenyl)benzene (TmPyPB).

[0008] Furthermore, by mass ratio, MTDATA: TmPyPB=1:(1-2).

[0009] A method for optimizing the performance of small molecule organic solar cell devices based on external electric field modulation of interfacial electronic coupling, the method comprising: applying an external electric field with adjustable direction and intensity to the active layer through an external power source, adjusting the external electric field intensity within -10 × 10 -5 au to 10×10 -5 Within the au range.

[0010] Furthermore, the external electric field strength is adjusted to -10×10 -5 au.

[0011] Furthermore, the method for determining the adjustment range of the external electric field intensity includes the following steps:

[0012] (1) Using Gaussian 16 software, the ground-state geometry of the donor material MTDATA and the acceptor material TmPyPB was optimized at the theoretical level of B3LYP / 6-31G(d) to obtain a stable configuration;

[0013] (2) Based on the optimized stable configuration, the leading molecular orbitals of the donor material MTDATA and the acceptor material TmPyPB were calculated using time-dependent density functional theory (TD-DFT) to obtain the HOMO and LUMO energy levels of the donor material MTDATA and the acceptor material TmPyPB.

[0014] (3) Construct a donor-acceptor model system and apply a series of different external electric field intensities (F) along its charge transfer direction. ext The external electric field strength range is set to -15×10. -5 au to +15×10 -5 au;

[0015] (4) Using the CAM-B3LYP functional, the vertical excitation energy (ΔE) and transition dipole moment (μ) under different external electric field intensities were calculated by the finite field method. ij and the difference between the ground state and excited state dipole moments (Δμ);

[0016] (5) Calculate the electronic coupling matrix element (V) using the Generalized Mulliken-Hush (GMH) model according to formula (1). da );

[0017] (1)

[0018] (6) Calculate the recombination energy (λ) and Gibbs free energy (ΔG) under different external electric field intensities; determine the main target points for external electric field modulation;

[0019] (7) The calculated V da Substituting λ and ΔG into Marcus's electron transfer theory formula (3), the charge separation rate (K) under different external electric field intensities was monitored. CS ) and charge recombination rate (K CR );

[0020] (3)

[0021] Furthermore, the method also includes,

[0022] (8) Determination of the operating range of external electric field strength: Select a donor-acceptor model system to achieve a higher K value. CS With lower K CR The range of external electric field strength is used as the operating range of external electric field strength for small molecule organic solar cell devices.

[0023] Furthermore, the donor-recipient model system was selected to achieve the highest K0. CS With the lowest K CR The external electric field strength is used as the optimization point for the external electric field strength of small molecule organic solar cell devices.

[0024] The above-mentioned method for optimizing the performance of small molecule organic solar cell devices based on external electric field modulation of interface electronic coupling is applied in flexible electronic devices or building-integrated photovoltaic systems that include small molecule organic solar cell devices.

[0025] The beneficial effects of this invention are:

[0026] 1. This invention is the first to combine an external electric field modulation mechanism with the MTDATA / TmPyPB small molecule system. Through experimental and theoretical verification, it was found that the external electric field mainly affects the charge transfer rate by adjusting the electronic coupling matrix element (Vda), while the recombination energy (λ) and Gibbs free energy (ΔG) change relatively little. Within the preferred electric field range, the charge separation rate can be increased by about 17%, and the recombination rate can be reduced by about 18%, significantly improving device efficiency.

[0027] 2. This invention enables the performance optimization of small molecule organic solar cell devices through real-time control of an external electric field, avoiding the synthesis of complex materials and device modification, and reducing costs.

[0028] 3. The method for determining the range of external electric field intensity provided by this invention has a clear control mechanism and is based on the Marcus electron transfer theory, thus having theoretical support.

[0029] 4. The method for determining the range of external electric field intensity provided by this invention is applicable to a variety of small molecule donor-acceptor systems and has wide applicability.

[0030] 5. The small molecule organic solar cell device provided by this invention has a simple structure and is easy to integrate into flexible and wearable devices. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of a small molecule organic solar cell device according to the present invention.

[0032] Figure 2 This is the stable configuration of the donor material MTDATA and the acceptor material TmPyPB in the embodiments of the present invention.

[0033] Figure 3 This is the HOMO-LUMO energy level diagram of the donor material MTDATA and the acceptor material TmPyPB in the embodiments of the present invention.

[0034] Figure 4 It is the external electric field strength coupled to the electron coupling matrix element (V da The influence curve of ).

[0035] Figure 5 This is the curve showing the effect of the external electric field strength on the recombination energy (λ).

[0036] Figure 6 This is the curve showing the effect of the external electric field intensity on the Gibbs free energy (ΔG).

[0037] Figure 7 It is the effect of external electric field strength on charge separation rate (K CS ) and charge recombination rate (K CR The influence curve of ). Detailed Implementation

[0038] The present invention will be further described below with reference to the embodiments, but the scope of protection of the present invention is not limited thereto.

[0039] Example 1: A small molecule organic solar cell device

[0040] like Figure 1 As shown, a small molecule organic solar cell device includes an active layer 1, an electrode, a hole transport layer 3, an electron transport layer 6, and an external electric field application device.

[0041] The active layer 1 is made of donor material MTDATA and acceptor material TmPyPB mixed in a mass ratio of 1:1.

[0042] The electrode, consisting of a cathode 4 and an anode 7, is used for charge collection.

[0043] The external electric field application device includes a negative plate electrode 2, a positive plate electrode 5, and a programmable external field power supply. The programmable external field power supply controls the application of an external electric field with adjustable direction and intensity to the active layer. The adjustable range of the external electric field intensity is -10 × 10⁻⁶. -5 au to 10×10 -5 au. Adjust the direction of the external electric field to align with the electron transfer path at the donor-acceptor interface.

[0044] The cathode 4, anode 7, hole transport layer 3, and electron transport layer 6 can be manufactured according to conventional techniques in the field. This invention is not limited to these components, and any existing technology can be used.

[0045] The structure of the small molecule organic solar cell device is as follows: with the active layer 1 as the center, a negative plate electrode 2, a hole transport layer 3 and a cathode 4 are arranged sequentially on one side of the active layer 1, and a positive plate electrode 5, an electron transport layer 6 and an anode 7 are arranged sequentially on the other side of the active layer 1; the positive plate electrode 5 and the negative plate electrode 2 are respectively connected to the positive and negative terminals of the external power supply.

[0046] Example 2: A method for optimizing the performance of small molecule organic solar cell devices based on external electric field modulation of interfacial electronic coupling

[0047] The method using the small molecule organic solar cell device of Example 1 includes: applying an external electric field with adjustable direction and intensity to the active layer through an external power source, and adjusting the external electric field intensity to -10 × 10 -5 au to 10×10 -5 Within the range of au. Preferably, the external electric field strength is adjusted to -10×10. -5 au. Adjust the direction of the external electric field to align with the electron transfer path at the donor-acceptor interface.

[0048] The method for determining the external electric field intensity adjustment range described above, in this embodiment, aims to illustrate how to determine the optimal external electric field operating range for a specific donor-acceptor material pair (such as MTDATA / TmPyPB) through theoretical calculations without relying on extensive trial-and-error experiments. The method includes the following steps:

[0049] I. Calculation of Molecular Structure and Electronic Properties:

[0050] The structures of MTDATA and TmPyPB are as follows:

[0051]

[0052] MTDATA TmPyPB

[0053] 1. Using Gaussian 16 software, the ground-state geometry of the donor material MTDATA and the acceptor material TmPyPB was optimized at the B3LYP / 6-31G(d) theoretical level to obtain a stable configuration. The results are as follows: Figure 2 .

[0054] 2. Based on the optimized stable configuration, the leading molecular orbitals of MTDATA and TmPyPB were calculated using time-dependent density functional theory (TD-DFT), such as... Figure 3 As shown, the HOMO and LUMO energy levels of the donor material MTDATA and the acceptor material TmPyPB were obtained. It was confirmed that the energy level difference provides sufficient driving force for charge separation.

[0055] II. Calculation and simulation of key parameters under external electric field:

[0056] 1. Construct a donor-acceptor (DA) model system and apply a series of different external electric field intensities (F) along its charge transfer direction. ext The external electric field strength range is set to -15×10. -5 au to +15×10 -5 au.

[0057] 2. Using the CAM-B3LYP functional, the vertical excitation energy (ΔE) and transition dipole moment (μ) under different external electric field intensities are calculated using the finite field method. ij ) and the difference between the ground state and excited state dipole moments (Δμ).

[0058] 3. Based on the above results, the core parameter—the electronic coupling matrix element (V)—is calculated using the Generalized Mulliken-Hush (GMH) model according to formula (1). da The calculation results are as follows: Figure 4 As shown, V da The value monotonically increases from 0.0994 eV to 0.1097 eV as the external electric field strength increases, demonstrating the effective and directional control capability of the external electric field over this parameter.

[0059] (1)

[0060] 4. Calculate the recombination energy (λ) and Gibbs free energy (ΔG) under different external electric field intensities; determine the main target points for external electric field modulation;

[0061] 4.1) Recombination energy

[0062] The recombination energy (λ) is composed of the internal recombination energy (λ). i ) and external recombination energy (λ) S )composition:

[0063] (2.1)

[0064] Internal recombination energy λ i Described as: (2.2)

[0065] (2.3)

[0066] (2.4)

[0067] Among them, E(A) - E(A) represents the energy value in the receptor anion configuration and the energy value in the optimized ground-state neutral receptor configuration, E(D) represents the energy value in the receptor anion configuration and the energy value in the optimized ground-state neutral receptor configuration. - E(D) and E(N) represent the energies in the neutral donor configuration and the energies in the donor cation configuration, respectively. The calculation results are as follows: Figure 5 .

[0068] 4.2) Gibbs Free Energy

[0069] The following equation is used to estimate the Gibbs free energy (ΔG) of the charge separation process associated with the external electric field. CS )

[0070] (2.5)

[0071] (2.6)

[0072] Among them, E D* E D+ E A and E A- It is the total energy of the isolated donor in the lowest excited state, the cation state with different external fields, and the stable geometry of the ground state and anion state in the acceptor geometry.

[0073] 4.3) ΔG involving charge recombination CR as follows:

[0074] (2.7)

[0075] (2.8)

[0076] Among them, ΔE is set coul ≈ΔE b , where ΔE b This is the exciton binding energy, which can be quantitatively analyzed under the control of an external electric field. The calculation results are as follows: Figure 6 .

[0077] Reference Figure 5 and Figure 6 The comparison chart, compared to V daThese two are minimally affected by the external electric field (the change range is <5%), thus theoretically determining that the electronic coupling matrix element is the main target for external electric field modulation.

[0078] III. Prediction of charge transfer rate and determination of optimal operating point:

[0079] 1. Calculate the V da Substituting λ and ΔG into Marcus's electron transfer theory formula (3), the charge separation rate (K) under different external electric field intensities was monitored. CS ) and charge recombination rate (K CR ); the results are as follows Figure 7 As shown, K CS With K CR All of them exhibit a regular evolution with changes in electric field strength.

[0080] (3)

[0081] 2. Select a donor-recipient model system to achieve a higher K0 ratio. CS With lower K CR The range of external electric field strength is used as the operating range of the external electric field strength for small molecule organic solar cell devices. Preferably, the range is selected to achieve the highest K0 in the donor-acceptor model system. CS With the lowest K CR The external electric field strength is used as the optimization point for the external electric field strength of small molecule organic solar cell devices.

[0082] The optimization conclusion of this embodiment: Theoretical predictions show that when the external electric field strength is -10×10 -5 When near au, the system can achieve Highest K CS With the lowest K CR When the ratio of these two values ​​reaches its maximum, it indicates that the device's photoelectric performance is optimal. This theoretically optimal value is the core parameter guiding the operation of actual devices.

[0083] External electric field strength applied: Based on the above theoretical calculations, the optimal operating point is determined to be: external electric field strength of -10 × 10⁻⁶. - 5 au applies a corresponding voltage to the device via a programmable power supply to generate an external electric field of the desired strength in the active layer region.

[0084] Performance Trend Validation: Under standard test conditions (e.g., AM 1.5G), the current density-voltage (JV) curves of the device under optimized external electric field and without external electric field were compared. The results show that under optimized electric field, the short-circuit current density (Jsc) and fill factor (FF) of the device are improved, which is consistent with the theoretically predicted trend of charge transfer rate optimization. This further demonstrates the effectiveness of theoretical calculation guidance, rather than limiting specific absolute performance values.

[0085] Based on the above theoretical methods, this invention can be applied to a variety of scenarios:

[0086] 1) Flexible wearable devices: The small molecule organic solar cell device of this invention is applied to a flexible substrate (such as PET), and an optimized external electric field strength of -10×10 is applied. -5 au, to improve its energy conversion efficiency and stability under bending conditions.

[0087] 2. Building-integrated photovoltaics (BIPV): The small-molecule organic solar cell device of this invention is integrated into building glass, and the external electric field strength is dynamically adjusted to -10×10 based on the ambient light intensity. -5 au enables adaptive and efficient power generation on building surfaces.

[0088] This invention is the first to combine an external electric field modulation mechanism with the MTDATA / TmPyPB small molecule system. Through experimental and theoretical verification, it was found that the external electric field mainly affects the charge transfer rate by adjusting the electronic coupling matrix element (Vda), while the recombination energy (λ) and Gibbs free energy (ΔG) change relatively little. Within the preferred electric field range, the charge separation rate can be increased by about 17%, and the recombination rate can be reduced by about 18%, significantly improving device efficiency.

Claims

1. A small-molecule organic solar cell device, characterized in that, The small molecule organic solar cell device includes an active layer (1), electrodes, and an external electric field application device; the active layer (1) is made of a mixture of donor and acceptor materials; the electrodes consist of a cathode (4) and an anode (7); the external electric field application device includes a negative plate electrode (2), a positive plate electrode (5), and an external power supply; with the active layer (1) as the center, a negative plate electrode (2), a hole transport layer (3), and a cathode (4) are arranged sequentially on one side of the active layer (1), and a positive plate electrode (5), an electron transport layer (6), and an anode (7) are arranged sequentially on the other side of the active layer (1); the positive plate electrode (5) and the negative plate electrode (2) are respectively connected to the positive and negative terminals of the external power supply.

2. The small molecule organic solar cell device according to claim 1, characterized in that, The donor material is MTDATA, and the acceptor material is TmPyPB.

3. The small molecule organic solar cell device according to claim 2, characterized in that, By mass ratio, MTDATA : TmPyPB = 1 : (1-2).

4. A method for optimizing the performance of small molecule organic solar cell devices based on external electric field modulation of interfacial electronic coupling, characterized in that, A method for optimizing the performance of the small molecule organic solar cell device according to claim 2 or 3 based on the modulation of interface electronic coupling by an external electric field, the method comprising: applying an external electric field of adjustable direction and intensity to the active layer (1) by an external power source, and adjusting the intensity of the external electric field within -10×10 -5 au to 10×10 -5 Within the au range.

5. The method for optimizing the performance of small molecule organic solar cell devices based on external electric field modulation of interface electronic coupling according to claim 4, characterized in that, Adjust the external electric field strength to -10×10 -5 au.

6. The method for optimizing the performance of small molecule organic solar cell devices based on external electric field modulation of interface electronic coupling according to claim 4, characterized in that, The method for determining the adjustment range of the external electric field intensity includes the following steps: (1) Using Gaussian 16 software, the ground-state geometry of the donor material MTDATA and the acceptor material TmPyPB was optimized at the theoretical level of B3LYP / 6-31G(d) to obtain a stable configuration; (2) Based on the optimized stable configuration, the leading molecular orbitals of the donor material MTDATA and the acceptor material TmPyPB were calculated using time-dependent density functional theory (TD-DFT) to obtain the HOMO and LUMO energy levels of the donor material MTDATA and the acceptor material TmPyPB. (3) Construct a donor-acceptor model system and apply a series of different external electric field intensities (F) along its charge transfer direction. ext The external electric field strength range is set to -15×10. -5 au to +15×10 -5 au; (4) Using the CAM-B3LYP functional, the vertical excitation energy (ΔE) and transition dipole moment (μ) under different external electric field intensities were calculated by the finite field method. ij and the difference between the ground state and excited state dipole moments (Δμ); (5) Calculate the electronic coupling matrix element (V) using the Generalized Mulliken-Hush (GMH) model according to formula (1). da ); （1） (6) Calculate the recombination energy (λ) and Gibbs free energy (ΔG) under different external electric field intensities; determine the main target points for external electric field modulation; (7) The calculated V da Substituting λ and ΔG into Marcus's electron transfer theory formula (3), the charge separation rate (K) under different external electric field intensities was monitored. CS ) and charge recombination rate (K CR ); （3）。 7. The method for optimizing the performance of small molecule organic solar cell devices based on external electric field modulation of interface electronic coupling according to claim 6, characterized in that, The method also includes, (8) Determination of the operating range of external electric field strength: Select a donor-acceptor model system to achieve a higher K value. CS With lower K CR The range of external electric field strength is used as the operating range of external electric field strength for small molecule organic solar cell devices.

8. The method for optimizing the performance of small molecule organic solar cell devices based on external electric field modulation of interface electronic coupling according to claim 7, characterized in that, Choosing the donor-recipient model system to achieve the highest K CS With the lowest K CR The external electric field strength is used as the optimization point for the external electric field strength of small molecule organic solar cell devices.

9. The application of the method for optimizing the performance of small molecule organic solar cell devices based on external electric field modulation of interface electronic coupling as described in any one of claims 4-8 in flexible electronic devices or building-integrated photovoltaic systems comprising the small molecule organic solar cell devices described in claim 2 or 3.

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