Flexible organic single crystal with photoelectric property as well as preparation method and application of flexible organic single crystal
By using the organic semiconductor material PODABT containing benzothiadiazonoquinoxaline, the solution method is used to grow flexible organic single crystals, which solves the problems of unoptimized photoelectric performance and low crystal quality stability in the prior art, and realizes the preparation of high-quality flexible organic single crystals and the application of high-performance optoelectronic devices.
Patent Information
- Application Number
- CN202510327035.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-19
- Publication Date
- 2025-06-20
AI Technical Summary
The photoelectric properties of existing organic single crystals are not fully optimized, the photoresponse characteristics are poor, and the crystal quality stability is low, making it difficult to apply to flexible electronic devices.
Using PODABT, an organic semiconductor material containing benzothiadiazonoquinoxaline, a flexible organic single crystal with photoelectric properties was grown on a pretreated silicon wafer by solution method, and the growth environment parameters were controlled to regulate the morphology of the single crystal.
High-quality flexible organic single crystals are obtained, with significant photoelectric properties and a maximum saturation mobility of 0.01cm2V-1s-1, which is suitable for the preparation of high-performance organic single crystal field effect transistors.
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Figure CN120174462A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of organic electronic devices, and particularly relates to a flexible organic single crystal with optoelectronic properties, a preparation method thereof, and an application thereof. Background Art
[0002] Organic semiconductor materials have the advantages of light weight, low price, chemical modifiability, solution processability, etc., and have broad application prospects in the fields of organic electronic devices such as organic field effect transistors (OFETs), organic light emitting diodes (OLEDs), and organic solar cells (OSCs). Organic single crystals have the advantages of long-range molecular order, few defects, and low grain boundary density, and generally have high carrier mobility, which can well improve the electrical properties of organic field effect transistors. So far, although breakthroughs have been made in the electrical characteristics of OSCs (organic single crystals), the inherent optoelectronic properties of the devices have not been fully optimized, and the light response characteristics are also difficult to be satisfactory. On the other hand, the crystal quality stability of organic single crystals is low. The crystallization process of organic single crystals strongly depends on external environmental conditions, including the type of solvent, temperature, solution concentration, and surfactant, and the vast majority of organic single crystals do not have flexibility and are prone to fracture or cracking under external stimuli, which is not conducive to the construction of flexible electronic devices. So far, it is still a difficult task to kinetically control the growth of different organic semiconductor single crystals and then optimize to obtain excellent optoelectronic properties and apply them to corresponding devices. Therefore, it is very important to develop a simple, convenient, and low-cost preparation method for high-quality flexible organic single crystals. Summary of the Invention
[0003] The present invention provides a flexible organic single crystal with optoelectronic properties, a preparation method thereof, and an application thereof. The organic single crystal prepared by the method of the present invention has a controllable morphology, is flexible, and is prone to fracture or cracking under external stimuli.
[0004] Technical Solution: A preparation method for a flexible organic single crystal with optoelectronic properties, after dissolving an organic semiconductor material containing benzothiadiazoloquinoxaline in an organic solvent, a flexible organic single crystal with optoelectronic properties is grown by a solution method; the organic semiconductor material containing benzothiadiazoloquinoxaline is PODABT, and the structural formula is as shown in formula (Ⅰ):
[0005]
[0006] Further, the preparation method includes the following steps:
[0007] Step 1: Drop toluene into the organic semiconductor material, and perform ultrasonic treatment to fully dissolve the semiconductor material to obtain a stock solution;
[0008] Step 2: Drop the stock solution onto the pretreated silicon wafer, and let it stand until the stock solution completely volatilizes to obtain a flexible organic single crystal with optoelectronic properties.
[0009] Furthermore, by controlling the temperature during standing in Step 2, the width of the organic single crystal can be controlled. When the standing temperature is within 15 - 35°C, the width of the organic single crystal increases as the standing temperature rises.
[0010] Furthermore, in Step 1, the time for ultrasonic treatment is 30 min.
[0011] Furthermore, in Step 1, the concentration of the organic semiconductor material in the stock solution is 0.2 - 0.5 mg / mL.
[0012] Furthermore, in Step 2, the pretreatment includes: successively cleaning the silicon wafer with deionized water, acetone, and ethanol, and then performing ultraviolet treatment and octadecylsilane modification on the silicon wafer surface.
[0013] Furthermore, in Step 2, the standing time is 12 - 24 h.
[0014] The flexible organic single crystal with optoelectronic properties prepared by the preparation method according to the present invention can be used to prepare an organic single crystal field effect transistor.
[0015] Beneficial effects:
[0016] 1) By selecting an organic semiconductor material containing benzothiadiazoloquinoxaline, dissolving it in an organic solvent, and growing an organic single crystal by the solution method, the present invention realizes the morphology control of the organic single crystal by changing the growth environment parameters, thereby obtaining a high-quality flexible organic single crystal.
[0017] 2) The OFET device prepared based on the organic crystal prepared by the present invention has obvious optoelectronic properties. Its highest saturation mobility is 0.01 cm 2 V -1 s -1 , and the threshold voltage of its typical device under dark field conditions is -10 V. Under the irradiation of ultraviolet light or white light, the threshold voltage can be significantly reduced to -5 V, while the mobility has no obvious change, which is beneficial to promoting the creation of a future high-performance optoelectronic organic crystal material system. Description of the Drawings
[0018] Figure 1 It is the synthesis route diagram of the semiconductor material PODABT used in the present invention.
[0019] Figure 2 It is the 1H NMR spectrum of the semiconductor material PODABT used in the present invention.
[0020] Figure 3MALDI-TOP mass spectrum of semiconductor material PODABT used in the present invention.
[0021] Figure 4 Schematic diagram of the flexible organic single crystal with optoelectronic properties prepared in Example 2 of the present invention.
[0022] Figure 5 Flexibility diagram of the flexible organic single crystal with optoelectronic properties prepared in Example 2 of the present invention.
[0023] Figure 6 SEM image of the flexible organic single crystal with optoelectronic properties prepared in Example 2 of the present invention.
[0024] Figure 7 AFM image of the flexible organic single crystal with optoelectronic properties prepared in Comparative Example 2 of the present invention.
[0025] Figure 8 SAED image of the flexible organic single crystal with optoelectronic properties prepared in Example 2 of the present invention.
[0026] Figure 9 Typical morphology pictures of single crystals grown at 15 °C, 25 °C, and 35 °C in Example 3 of the present invention.
[0027] Figure 10 Crystal width distribution diagram of crystals grown at 15 °C, 25 °C, and 35 °C in Example 3 of the present invention and the change relationship of the average width of crystals at different growth temperatures.
[0028] Figure 11 Crystal growth diagrams of crystals grown at 8 °C - 10 °C and 40 °C in Example 3 of the present invention.
[0029] Figure 12 Schematic diagram of the organic single crystal field effect transistor prepared in Example 4 of the present invention.
[0030] Figure 13 Mobility of the organic field effect transistors prepared with different crystal widths in Example 4 of the present invention.
[0031] Figure 14 Characteristic curve of the organic field effect transistor prepared in Example 5 of the present invention.
[0032] Figure 15 Characteristic curves of the organic field effect transistors measured under different light sources prepared in Comparative Example 5 of the present invention. Detailed Description of the Invention
[0033] The technical solution of the present invention will be described in detail below through examples, but the protection scope of the present invention is not limited to the described examples. The raw materials used in the following examples are all commercially available in the art without special description.
[0034] Example 1: Preparation Method of Semiconductor Material PODABT and Silicon Wafer Cleaning Method
[0035] The preparation method of semiconductor material PODABT is specifically as follows:
[0036] 1) Synthesis of intermediate monomer DABTH: Under the conditions of light avoidance and N2 protection, monomer 4,5-dinitro-1,2-diaminobenzene (5 g, 25.25 mmol), 30 mL of toluene, and 120 mL of thionyl chloride (1 mol / L in CH2Cl2) were added to a dry reaction flask and reacted at 90 °C for 36 h. After removing all solvents, iron powder (10 g, 0.18 mol) and 150 mL of acetic acid were added to the reaction flask under light avoidance conditions and reacted at 80 °C for 4 h. After cooling to room temperature, it was quenched with H2O, extracted with DCM (dichloromethane), and the solid crude product obtained after removing the solvent was purified by alumina with a mesh size of 100 - 200 using ethyl acetate (EAC) and methanol (MT) with EAC:MT = 10:1 as the eluent to obtain yellow monomer DABTH (3.02 g, yield 72%).
[0037] 2) Synthesis of intermediate monomer ADO: 5,6-dibromoacenaphthene (10 g, 32 mmol), chromium trioxide (19.2 g, 192 mmol), and 150 mL of acetic anhydride were added to a dry reaction flask and reacted at 70 °C for 2 h. After the reaction ended, it was cooled to room temperature, H2O (400 mL) was added, and then 77 mL of concentrated hydrochloric acid was slowly added and stirred at room temperature for 2 h. It was poured into 200 mL of water, filtered by suction, and dried to obtain yellow solid ADO (8.14 g, yield 74%).
[0038] 3) Synthesis of precursor ADO-R: Under the conditions of light avoidance and N2 protection, monomer R with a borate group (4.0 equiv), ADO (1.0 equiv), Pd(pph3)4 (0.2 equiv), TBAB (tetrabutylammonium bromide, 0.5 equiv), 2M K2CO3 solution (20 mL), and toluene solution (40 mL) were added to a dry reaction flask and reacted at 95 °C for 24 h. After the reaction ended, it was cooled to room temperature, quenched with H2O, extracted with DCM, and the solid obtained by removing the solvent from the organic phase was purified by a silica gel column with a mesh size of 300 - 400 using PE (petroleum ether) and DCM as the eluent to obtain the corresponding dark red precursor ADO-R.
[0039] 4) Synthesis of the target compound PODABT: Under light protection conditions, the precursor ADO-R (1.0 equiv), DABTH (1 equiv), glacial acetic acid (10 mL), and chloroform solution (30 mL) were added to the reaction flask respectively, and the reaction was carried out at 70 °C for 4 h. After the reaction, it was cooled to room temperature and poured into 200 mL of water. The separated solid was filtered out, washed with water and cold methanol, and the obtained solid was purified by a silica gel column with 300 - 400 mesh using DCM and EAC as eluents to obtain the corresponding target compound PODABT.
[0040] The synthesis route of the semiconductor material PODABT is as Figure 1 shown, Figure 2 and 1 Figure 9 is the Figure 3 H NMR spectrum, and
[0041] The pretreatment method of the silicon wafer is as follows:
[0042] The silicon wafer is a heavily doped p-type SiO2 / Si wafer, with 300 nm thick SiO2 thermally pressed on one side and having a capacitance of 10.5 nF·cm -2 . Its pretreatment steps include:
[0043] Step 1: The silicon wafer was ultrasonically cleaned with deionized water, acetone, and ethanol in sequence, and each solvent cleaning was for 15 minutes. Then, it was ultrasonically cleaned with deionized water for 15 minutes to rinse the surface of the silicon wafer clean;
[0044] Step 2: After quickly drying with nitrogen, it was subjected to UV treatment for 15 minutes;
[0045] Step 3: The silicon wafer was placed in a petri dish dropwise with octadecylsilane solution, placed in an oven and evacuated, and baked at 120 °C for 3 hours;
[0046] Step 4: The silicon wafer was taken out and ultrasonically cleaned in n-hexane, chloroform, and isopropanol in sequence, and each solvent cleaning was for 4 min;
[0047] Step 5: Repeat Step 4 to obtain the pretreated silicon wafer.
[0048] In Examples 2 - 5, the semiconductor material PODABT used was prepared by the method in this example, and the pretreatment method of the silicon wafer was also the silicon wafer pretreatment method in this example.
[0049] Example 2: Preparation method of a flexible organic single crystal with optoelectronic properties
[0050] This example provides a preparation method of a flexible organic single crystal with optoelectronic properties, specifically as follows:
[0051] 1) Weigh 0.3 mg of the semiconductor material PODABT, add 600 μL of toluene dropwise thereto, and perform ultrasonic oscillation treatment for 30 min to fully dissolve the semiconductor material, obtaining a stock solution with a concentration of 0.5 mg / mL; The ultrasonic machine is used at room temperature, with a frequency of 40 Khz and a power of 240 W.
[0052] 2) Drop the stock solution onto the pretreated silicon wafer, and let it stand at 25 °C for 24 h. After the stock solution has completely evaporated, a flexible organic single crystal with optoelectronic properties is obtained.
[0053] Figure 4 Schematic diagram of the flexible organic single crystal with optoelectronic properties prepared in Example 2 of the present invention. It can be seen that the single crystal exhibits a regular rectangular morphology. Figure 5 Flexibility diagram of the flexible organic single crystal with optoelectronic properties prepared in Example 2 of the present invention. The crystal can be folded without breaking. Figure 6 SEM morphology image of the flexible organic single crystal with optoelectronic properties prepared in Example 2 of the present invention. Figure 7 AFM morphology image of the flexible organic single crystal with optoelectronic properties prepared in Example 2 of the present invention, with a thickness of about 100 nm. Figure 8 SAED pattern of the flexible organic single crystal with optoelectronic properties prepared in Example 2 of the present invention. It can be seen that the crystal has regular electron diffraction spots, indicating its single crystal nature.
[0054] Example 3: Morphology control method of organic single crystal with optoelectronic properties
[0055] This example provides a morphology control method of an organic single crystal with optoelectronic properties, specifically as follows:
[0056] 1) Weigh 0.3 mg of the semiconductor material PODABT, add 600 μL of toluene dropwise thereto, and perform ultrasonic oscillation treatment for 30 min to fully dissolve the semiconductor material, obtaining a stock solution with a concentration of 0.5 mg / mL;
[0057] 2) Drop the stock solution onto the pretreated silicon wafer, and let it stand at 15 °C, 25 °C, and 35 °C for 24 h respectively. After the stock solution has completely evaporated, single crystal morphologies of different sizes are obtained.
[0058] Figure 9 Typical morphology pictures of single crystals of different sizes prepared in Example 3 of the present invention. It can be seen that the crystal is significantly affected by temperature, and its width increases with the increase in temperature. Figure 9 In (a), (b), and (c) are the single crystal morphology pictures obtained at 15 °C, 25 °C, and 35 °C respectively. Figure 10(a), (b), and (c) are the crystal width distribution diagrams of crystals grown at 15°C, 25°C, and 35°C respectively, and (d) is the variation relationship of the average width of crystals at different growth temperatures. From Figure 9 and Figure 10 it can be observed that there is a significant positive correlation between the single crystal width and the growth temperature. The average widths of the crystals grown at 15°C, 25°C, and 35°C are 3μm, 15.6μm, and 31.6μm respectively.
[0059] When the crystal growth temperature is 8°C - 10°C and 40°C, the crystal growth conditions are as shown in Figure 11 . When the crystal growth temperature is relatively low (8°C - 10°C), as shown in (a) in Figure 11 , it is difficult for the crystals to grow large, the quality decreases significantly, and there is an easy over - stacking phenomenon, resulting in difficulty in fabricating OFET devices, and the crystal width is less than 1.7μm. When the growth temperature is too high (40°C), as shown in (b) in Figure 11 , the crystal quality drops sharply, the surface defects increase, and almost no electrical properties can be exhibited. The crystal width is distributed between 40 - 70μm. Either too low or too high temperature is not conducive to the high - quality growth of crystals.
[0060] Example 4: Preparation method of organic single - crystal field - effect transistor
[0061] This example provides a preparation method of an organic single - crystal field - effect transistor. The structure of the organic single - crystal field - effect transistor is as shown in Figure 12 , specifically as follows:
[0062] 1. Select a heavily doped p - type SiO2 / Si silicon wafer as the substrate, where the heavily doped Si is the gate electrode 4, and the 300 - nm - thick SiO2 formed by single - side hot - pressing is the insulating layer 3. Process according to steps 1 and 2 in the silicon wafer pretreatment method in Example 1. According to step 3, place the silicon wafer in a petri dish drop - added with octadecylsilane solution, with the SiO2 side facing up, place it in an oven and evacuate to vacuum, bake at 120°C for 3 hours to form an OTS modification layer 2, and then process according to steps 4 and 5.
[0063] 2. Prepare crystals from the stock solution prepared in Example 3 under the conditions of 15°C, 25°C, and 35°C respectively. 25 OFET devices are prepared for the crystals under each condition, with a total of 75 device samples, and their electrical properties are tested. Specific operations:
[0064] The stock solution prepared in Example 3 was dropped onto the surface of the modification layer 2 and allowed to stand at 15 °C, 25 °C, and 35 °C for 24 h respectively. After the solution evaporated, an organic single crystal 1 was obtained on the modification layer 2. Evaporation electrode treatment was carried out at both ends of the organic single crystal 1, and gold with a thickness of 50 nm was deposited on its surface to prepare the source-drain electrodes 5, thereby obtaining an organic single crystal field-effect transistor.
[0065] For the organic single crystal field-effect transistor prepared in Example 4, its electrical properties were tested in the dark field, and the results are as Figure 13 shown, Figure 13 where (a) shows the relationship between the mobility of the OFET device and the crystal width in the crystals prepared at different growth temperatures (15 °C, 25 °C, 35 °C), and (b) shows the relationship between the average mobility of the crystals at each growth temperature.
[0066] From Figure 13 (a), it can be observed that there is a certain positive correlation between the crystal width and the device mobility, that is, the device mobility increases with the increase of the crystal width. The average device mobilities of the crystals under the three temperature conditions are 0.00046 cm 2 V-1s-1, 0.004 cm 2 V-1s-1, and 0.0051 cm 2 V-1s-1 respectively, and their change trend is as Figure 13 (b) shown. It should be noted that in the devices with wider crystals prepared at 35 °C, the mobility shows a saturation trend, and with the further increase of the crystals, the mobility no longer increases significantly. In addition, for the linear crystal devices grown at 15 °C, their mobilities are generally lower than 0.001 cm 2 V-1s-1. These results indicate that the crystal width has a significant impact on the electrical properties of the device.
[0067] Example 5: Preparation method of organic single crystal field-effect transistor
[0068] This example provides a preparation method of an organic single crystal field-effect transistor. The structure of the organic single crystal field-effect transistor is as Figure 12 shown, specifically:
[0069] 1. A heavily doped p-type SiO2 / Si silicon wafer was selected as the substrate, where the heavily doped Si was the gate electrode 4, and the 300-nm-thick SiO2 by single-sided hot pressing was the insulating layer 3. The treatment was carried out according to steps 1 and 2 in the silicon wafer pretreatment method in Example 1. According to step 3, the silicon wafer was placed in a petri dish dropwise added with octadecylsilane solution, with the SiO2 side facing up, placed in an oven and evacuated to vacuum, and baked at 120 °C for 3 hours to form the OTS modification layer 2, and then the treatment was carried out according to steps 4 and 5.
[0070] 2. Then, the stock solution prepared in Example 2 was dripped onto the surface of the modified layer 2 and allowed to stand at 25°C for 24 hours. After the solution evaporated, an organic single crystal 1 was obtained on the modified layer 2. Electrode treatment was performed on both ends of the organic single crystal 1, and 50 nm thick gold was deposited on its surface to prepare source and drain electrodes 5, thereby obtaining an organic single crystal field effect transistor.
[0071] The electrical properties of the organic single crystal field effect transistor prepared in Example 5 were tested under dark field conditions. The results are as follows: Figure 14 As shown, Figure 14 The field effect carrier mobility of the flexible organic single crystal with photoelectric performance prepared in this embodiment can reach up to 0.01 cm 2 V -1 s -1 , the threshold voltage is -8.5V, with higher performance.
[0072] The electrical properties of the organic single crystal field effect transistor prepared in Example 5 were tested under dark field, white light source provided by the probe station, and 405 nm ultraviolet light irradiation conditions, and the results are shown in Tables 1 and Figure 15 As shown, Figure 15 This is the measured characteristic curve of a typical organic field effect transistor.
[0073] Table 1
[0074]
[0075] According to Table 1 and Appendix Figure 13 It can be seen that:
[0076] The field effect carrier mobility of the flexible organic single crystal with photoelectric properties prepared in this embodiment can reach 0.0021cm under dark field conditions. 2 V -1 s -1 , the threshold voltage is -10V, with high performance. When the light source changes, the transfer curve changes significantly, showing that the curve shifts to the right as a whole, but the trend does not change significantly, which makes the change of carrier mobility relatively small, from 0.0021cm 2 V -1 s -1 Increased to 0.0027cm 2 V -1 s -1 (white light) and 0.003cm 2 V -1 s -1(405nm ultraviolet light), the threshold voltage changes significantly, decreasing from -10V to -5.6V (white light) and -5.5V (405nm ultraviolet light). The above indicates that the change in the light source mainly affects its threshold voltage, while having a relatively small impact on the carrier mobility. This crystal material has the potential as an optical switch.
[0077] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as a limitation on the invention itself. Various changes can be made in its form and details without departing from the spirit and scope of the invention.
Claims
1. A method for preparing a flexible organic single crystal with photoelectric properties, characterized in that: After dissolving an organic semiconductor material containing benzothiadiazole and quinoxaline in an organic solvent, a flexible organic single crystal with photoelectric properties is grown by a solution method; the organic semiconductor material containing benzothiadiazole and quinoxaline is PODABT, and the structural formula is shown in formula (I):
2. The preparation method according to claim 1, characterized in that: The steps include: Step 1: adding toluene dropwise to the organic semiconductor material, and subjecting the organic semiconductor material to ultrasonic treatment to fully dissolve the semiconductor material to obtain a stock solution; Step 2: drip the stock solution onto the pretreated silicon wafer, and let it stand to allow the stock solution to completely evaporate, thereby obtaining a flexible organic single crystal with photoelectric properties.
3. The preparation method according to claim 2, characterized in that: The width of the organic single crystal is controlled by controlling the standing temperature in step 2. When the standing temperature is within the range of 15 to 35° C., the width of the organic single crystal increases as the standing temperature increases.
4. The preparation method according to claim 2, characterized in that: In step 1, the ultrasonic treatment time is 30 minutes.
5. The preparation method according to claim 2, characterized in that: In step 1, the concentration of the organic semiconductor material in the stock solution is 0.2-0.5 mg / mL.
6. The preparation method according to claim 2, characterized in that: In step 2, the pretreatment includes: using deionized water, acetone, and ethanol to clean the silicon wafer in sequence, and then ultraviolet treatment and octadecylsilane modification of the silicon wafer surface.
7. The preparation method according to claim 2, characterized in that: In step 2, the standing time is 12 to 24 hours.
8. A flexible organic single crystal with photoelectric properties prepared by the preparation method according to any one of claims 1 to 7.
9. Use of the flexible organic single crystal with photoelectric properties prepared by the preparation method according to any one of claims 1 to 7 in the preparation of an organic single crystal field effect transistor.