Organic photoelectric device for realizing high-efficiency long-range energy transfer through molecular orientation

Abstract

The invention discloses an organic photoelectric device for realizing efficient long-range energy transfer through molecular orientation. The surface plasma mediated energy transfer can realize long-range energy transfer far exceeding the radius of Frster. However, the conventional research is limited by the problem of dipole mismatching caused by random orientation of molecules in a thin film material, and high-efficiency long-range energy transfer is difficult to realize. In order to solve the problem of dipole mismatching caused by distance limitation of traditional non-radiative energy transfer and disordered film material molecular orientation, organic single crystal B3BtS (donor) and TTPSB (receptor) are provided as energy transfer carriers, a D-Ag-A sandwich structure separated by a 60nm Ag film is constructed, dipole matching is optimized by regulating and controlling the relative angle of the donor and the receptor, and the dipole mismatching problem is solved. The high-efficiency surface plasmon polariton mediated dipole moment angle depends on long-range energy transfer, and closed-loop verification of the phenomenon is completed from the double aspects of experiments and theories. Meanwhile, the established physical model not only provides reliable physical mechanism explanation for the orientation-dependent energy transfer process, but also accurately completes quantitative characterization of the energy transfer efficiency angle response characteristic, and provides a new path for improving the long-distance energy transfer efficiency and designing high-performance photoelectric devices.

Description

Technical Field

[0001] This invention relates to the field of organic optoelectronics. Specifically, we propose an organic optoelectronic device that achieves efficient long-range energy transfer through molecular orientation. Background Technology

[0002] Energy transfer refers to the process of transferring energy from a donor to an acceptor. As an important physical process, it has shown great significance in research related to photosynthesis, solar cells, and organic optoelectronic devices. Energy transfer is mainly divided into two types: radiative and non-radiative transitions. Non-radiative energy transfer has two common forms. One is Dexter energy transfer, which is achieved through the exchange of electron clouds between donor and acceptor molecules, with an effective interaction distance of extremely short distance (usually 1-2 nm). The other is the traditional Förster resonance energy transfer (FRET), which relies on dipole-dipole interactions between donor and acceptor molecules, with an effective interaction distance of less than 10 nm.

[0003] Surface plasmon polaritons (SPPs) have emerged as a novel mechanism for mediating energy transfer, demonstrating excellent application potential in long-range energy transport and attracting widespread attention from the scientific community in recent years. Compared to the energy transfer mechanisms mentioned above, SPP-mediated energy transfer overcomes distance limitations. Since Andrew and Barnes began their pioneering research in this field in 2004, their team was the first to demonstrate that SPPs can mediate energy transfer between donors and acceptors through metal films, laying a crucial theoretical foundation for this research direction. Although the coupling efficiency between the donor dipole moment and the SPP mode is high (over 95%), subsequent research has focused on further improving the overall efficiency of energy transfer. For example, Collini et al. found that an external electric field can significantly enhance the luminescence intensity during SPP-mediated energy transfer, producing a synergistic effect. Subsequently, researchers proposed multilayer metal-dielectric nanostructures, whose unique cascaded plasmon-plasmon coupling effect significantly improves energy transfer efficiency. In previous studies, researchers have mostly focused on thin films, while reports on energy transfer between organic crystals are relatively rare. Furthermore, the random and disordered molecular orientation within the structure of thin-film devices leads to dipole-dipole mismatch between the donor and acceptor, making it difficult to achieve efficient coupling between them and ultimately resulting in low energy transfer efficiency. Summary of the Invention

[0004] This invention relates to the field of organic optoelectronics. Specifically, given the long-range ordered molecular arrangement and anisotropic characteristics of organic single crystals, we focused our research on the long-range energy transfer process between organic single crystals. We selected B3BtS as the donor and TTPSB molecules as the acceptor, and prepared organic single crystals using a physical vapor transport method. These organic single crystals exhibited strong luminescence and high gain. By systematically controlling the relative angle between the donor B3BtS and the acceptor TTPSB, we investigated the influence of this factor on the energy transfer process. Simultaneously, by fixing the position of the donor, we further explored the optimal placement of the acceptor. The study found that when the two organic single crystals are arranged in parallel, the dipole matching effect is optimal, and the energy transfer efficiency between them is maximized. Conversely, when the single crystals are arranged perpendicularly, dipole mismatch leads to a significant decrease in energy transfer efficiency. This discovery provides an effective strategy for significantly improving energy transfer efficiency and opens up new research avenues for the design and development of optoelectronic devices.

[0005] It should be understood that the advantages of the present invention will be set forth in the following description, and the detailed description below is exemplary and illustrative. The objects and other advantages of the invention can be realized and obtained by means of the structures particularly pointed out in the description, claims, and drawings. Attached Figure Description

[0006] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings required in the description of the embodiments will be briefly introduced below:

[0007] Figure 1 This invention describes the process for preparing organic single crystals of the donor molecule B3BtS and the acceptor molecule TTPSB.

[0008] Figure 2 This refers to the configuration characterization and crystal stacking arrangement of the device designed in this invention.

[0009] Figure 3 This is a schematic diagram of the test and photoluminescence spectrum characterization of the device designed in this invention.

[0010] Figure 4 This is a characterization of the energy transfer efficiency and time-resolved photoluminescence of the device designed in this invention.

[0011] Figure 5 This invention relates to a surface plasmon polaritons-mediated, dipole orientation-dependent energy transfer mechanism in the device designed in this invention. Detailed Implementation

[0012] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings and examples, so that the process of how the present invention uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly. It should be noted that, as long as there is no conflict, the various features in the various embodiments of the present invention can be combined with each other, and the resulting technical solutions are all within the protection scope of the present invention.

[0013] Example 1:

[0014] Figure 1 As shown in Figure a, B3BtS organic single crystals were prepared using a physical vapor transport method: 6 mg of B3BtS powder was placed in a thermal evaporation boat and slowly pushed into the heating zone of a dual-temperature zone tube furnace, where the temperature was set to 430 °C. A clean glass substrate was placed in the deposition zone, where the temperature was 250 °C to facilitate crystal deposition. The argon flow rate inside the tube furnace was maintained at 55 mL / min, and the entire setup was run for 2 h to obtain B3BtS organic single crystals.

[0015] Figure 1 As shown in b, TTPSB organic single crystals were prepared using a physical vapor transport method: a hot evaporation boat containing 3 mg of TTPSB powder was slowly pushed into the heating zone of a dual-temperature zone tube furnace, with the heating zone temperature set at 320 °C. A clean glass substrate was placed in the deposition zone, with the deposition zone temperature set at 230 °C to facilitate crystal deposition. The argon flow rate inside the tube furnace was maintained at 15 mL / min, and the entire apparatus was run for 1 h to obtain TTPSB organic single crystals.

[0016] Example 2:

[0017] The device configuration designed in this invention consists of a donor layer and an acceptor layer spaced apart by a silver film (e.g.) Figure 2 As shown in Figure a), the body layer and acceptor layer are B3BtS(D) and TTPSB(A) organic single crystals prepared in Example 1, respectively. In this invention, all silver films are 60 nm thick. First, a 60 nm thick Ag film is thermally evaporated onto the B3BtS organic single crystal, and then a TTPSB organic single crystal is mechanically transferred onto it, ultimately obtaining the following... Figure 2 The device shown in the image and its cross-sectional scanning electron microscope image show the D-Ag-A sandwich structure.

[0018] Figure 2 b shows a schematic diagram of the packing of B3BtS molecules in a crystal, where the transition dipole moments along the long axis of the molecules are tilted at a 37° angle to the packing direction and stand on the (001) plane. Therefore, the projection of the B3BtS transition dipole moments in the length direction of the two-dimensional crystal is much larger than its projection in the width direction of the crystal.

[0019] Figure 2c shows a schematic diagram of the TTPSB molecules packed in a crystal, where the transition dipole moments along the long axis of the molecules are tilted at a 42° angle to the packing direction and stand on the (100) plane. Therefore, the projection of the TTPSB transition dipole moments in the length direction of the two-dimensional crystal is much larger than its projection in the width direction of the crystal. In summary, the orientation of the transition dipole moments of both the donor and acceptor is parallel to the long axis of the crystal.

[0020] Example 3:

[0021] Figure 3 Figure a shows a schematic diagram of the D-Ag-A device designed in this invention under pump laser irradiation. Here, the pump laser can selectively excite the overlapping region of the donor and acceptor layers. Independent excitation of the donor and acceptor layers is used as a control sample. To quantitatively study the angle-dependent energy transfer behavior in the D-Ag-A device, photoluminescence (PL) spectra are collected from the acceptor side under the conditions of donor-side excitation, donor fixation, and acceptor rotation to modulate the dipole moment angle α. Figure 3 The CD displays the PL spectra of D-Ag-A samples and control samples under different dipole moment angles α. All spectra are actual test results. Through comparison... Figure 3 The integral area of ​​the spectrum in a CD can be used to quantitatively calculate the energy transfer efficiency. The energy transfer efficiency is highest (0.85) when α = 0 (parallel dipole moment orientation); conversely, the energy transfer efficiency is lowest (0.26) when α = 90 (perpole moment orientation perpendicular to the target). In summary, it can be seen that the energy transfer efficiency in a parallel dipole moment orientation is more than three times that in a perpendicular orientation.

[0022] Example 4:

[0023] Figure 4 ab respectively show the relationship between the measured energy transfer efficiency and α, and the relationship between the energy transfer efficiency and cos... 2 The α-fit curve. The excellent agreement between the experimental data and the theoretical fit confirms the effectiveness of the established model. Figure 4 The CD method further utilizes a streak camera to conduct time-resolved photoluminescence testing on the device designed in this invention, enabling real-time monitoring of the energy transfer process from the perspective of excited-state dynamics.

[0024] Example 5:

[0025] Figure 5 This diagram illustrates the dipole moment angle-dependent energy transfer mechanism mediated by SPPs, visually demonstrating the regulatory effect of the donor-acceptor dipole moment angle α on the coupling strength and energy transfer efficiency of SPPs. The diagram shows the effect of α=0 (parallel dipole moment orientation). Figure 5 a) with α=90 (perpendicular orientation of dipole moment, Figure 5 b) Two typical states.

[0026] For α=0 ( Figure 5 a) The anisotropy of organic crystals causes the collective dipole moment (μ) of the donor (bottom layer, D) and acceptor (top layer, A) to be equal. D Collective μ A The donor exhibits a parallel orientation, at which point the effective transition dipole (μ) of the donor is... D ) and the effective transition dipole (μ) of the receptor A All of these orientations match the direction of the local electric field at the silver film-dielectric interface. This alignment can efficiently drive the oscillation of the electron charge density on the silver film surface, enabling strong coupling between organic excitons and surface plasmons, thereby exciting strong SPPs modes. These SPPs modes can be directionally transferred across the silver film and coupled to the acceptor side, ultimately achieving efficient energy transfer from the donor to the acceptor. This is in perfect agreement with the experimental result that the energy transfer efficiency is maximum (0.85) when α=0.

[0027] When α=90 ( Figure 5 b) Rotating the acceptor causes the collective molecular dipole moments of the donor and acceptor to be perpendicularly aligned, increasing the effective transition dipole (μ) of the acceptor. A The effective transition dipole (μ) of the donor and the donor D The spatial matching degree of SPPs is significantly reduced. At this point, the efficiency of electron charge density oscillations on the silver film surface driven by the donor dipole decreases dramatically. Organic excitons and surface plasmons only form weak coupling, resulting in a significant decrease in the excitation and transmembrane transfer efficiency of SPPs. This leads to a significant reduction in energy transfer efficiency from donor to acceptor, a characteristic consistent with the experimentally measured result that the energy transfer efficiency is minimum (0.26) at α=90. This also directly confirms that energy transfer efficiency increases with cos... 2 Quantitative laws governing the monotonic change of α.

Claims

1. An organic optoelectronic device that achieves efficient long-range energy transfer through molecular orientation.

2. The organic optoelectronic device for achieving efficient long-range energy transfer through molecular orientation as described in claim 1, characterized in that, Given the long-range ordered molecular arrangement and anisotropic characteristics of organic single crystals, the focus is on the long-range energy transfer process between organic single crystals, achieving efficient surface plasmon polaritons-mediated dipole moment angle-dependent long-range energy transfer.

3. The organic single-crystal donor and acceptor according to claim 2, characterized in that, Organic single crystals with regular morphology and high crystal quality can be easily obtained using physical vapor deposition methods.

4. The organic single crystal as described in claim 3, using organic single crystal B3BtS (donor) and TTPSB (acceptor) as energy transfer carriers, constructs an organic optoelectronic device with a D-Ag-A sandwich structure separated by a 60nm Ag film.

5. In the organic optoelectronic device as described in claim 4, when the two organic single crystals are arranged in parallel, the energy transfer efficiency between them is maximized because the dipole matching effect is optimal; conversely, when the single crystals are arranged in a perpendicular manner, the dipole mismatch will lead to a significant reduction in energy transfer efficiency.

6. As described in claim 5, by optimizing dipole matching by adjusting the relative angles of the donor and acceptor, efficient surface plasmon polaritrile-mediated dipole moment angle-dependent long-range energy transfer was achieved, and the closed-loop verification of this phenomenon was completed from both experimental and theoretical perspectives.

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