Phenothiazine self-assembled organic small molecule hole transport material and application thereof

Abstract

The application discloses a phenothiazine self-assembled organic small-molecule hole transport material and application thereof, wherein the structural general formula of the phenothiazine self-assembled organic small-molecule hole transport material is as follows: wherein R is n is 1-5. The disclosed phenothiazine self-assembled organic small-molecule hole transport material is based on a self-assembled monolayer design strategy, carboxylic acid anchoring groups and different bridging units are introduced into the phenothiazine molecular structure, the adjustment of the hole transport material molecular energy level and the improvement of the hole transport layer interface contact are realized. When the material is applied to a perovskite solar cell device as a non-doped hole transport layer, it shows good photoelectric conversion efficiency. Especially important is that the synthesis process is simple, the raw material source is wide and the price is low, so that the material is more competitive in practical application, and is expected to bring a new breakthrough to the development of perovskite solar cells.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic materials technology, specifically to a phenothiazine self-assembled organic small molecule hole transport material and its applications. Background Technology

[0002] Perovskite solar cell devices have made remarkable progress due to their excellent photoelectric performance. Since 2009, their photoelectric conversion efficiency (PCE) has exceeded 26%, which is very close to that of crystalline silicon-based solar cells, and they have great development potential.

[0003] Perovskite solar cell devices mainly consist of transparent conductive glass, an electron transport layer, a perovskite active layer, a hole transport layer, and conductive electrodes (metals or conductive metal oxides). Solar cell device structures can be divided into upright structures (nip) and inverted structures (pin). Inverted devices have advantages such as better stability, lower hysteresis, low-temperature fabrication, and suitability for flexible substrates, making them promising for commercial applications. The hole transport layer is a crucial component of perovskite solar cell devices. Besides enabling hole extraction and transport, it also passivates perovskite layer defects and protects the perovskite layer from damage by external moisture and oxygen. Hole transport materials can be categorized into inorganic materials (NiO, CuI, CuSCN, etc.), organic polymer materials (PTAA, PEDOT:PSS, P3HT, etc.), and small organic molecules (Spiro-OMeTAD, 2PACz, etc.). Compared to inorganic hole transport materials, the most significant advantage of organic hole transport materials is that energy levels can be tuned and molecularly energized through molecular design modification. The mainstream hole transport materials used in inverted solar cells are polymers PTAA and PEDOT:PSS. However, these materials suffer from drawbacks such as high cost, the need for dopants to improve hole mobility, and inherent corrosiveness and hygroscopicity, which can damage the perovskite layer and affect cell stability, thus limiting their large-scale application. Furthermore, the transparent conductive glass used in perovskite solar cell fabrication requires high-temperature annealing after sputtering deposition, resulting in high surface roughness and difficulty in controlling surface composition and work function, which is detrimental to charge transport at the interface. Summary of the Invention

[0004] The purpose of this invention is to provide a phenothiazine self-assembled organic small molecule hole transport material and its application. Using the phenothiazine self-assembled organic small molecule hole transport material in perovskite solar cells can improve the charge transport capability and photoelectric conversion efficiency of perovskite solar cells.

[0005] The technical solution of the present invention is as follows:

[0006] A phenothiazine self-assembled organic small molecule hole transport material, with the general structural formula as follows:

[0007]

[0008] R1 and R2 are independently selected from One of them.

[0009] Preferably, the structural formula of the above-mentioned phenothiazine self-assembled organic small molecule hole transport material is as follows:

[0010]

[0011] Application of the above-mentioned phenothiazine self-assembled organic small molecule hole transport material in the fabrication of perovskite solar cell devices.

[0012] A phenothiazine self-assembled organic small molecule hole transport material, with the following general structural formula:

[0013]

[0014] R3 and R4 are each independently selected from One of them.

[0015] Preferably, the structural formula of the above-mentioned phenothiazine self-assembled organic small molecule hole transport material is as follows:

[0016]

[0017] Application of the above-mentioned phenothiazine self-assembled organic small molecule hole transport material in the fabrication of perovskite solar cell devices.

[0018] A phenothiazine self-assembled organic small molecule hole transport material, with the general structural formula as follows:

[0019]

[0020] Where n = 1 to 5.

[0021] Preferably, the structural formula of the above-mentioned phenothiazine self-assembled organic small molecule hole transport material is as follows:

[0022]

[0023] Application of the above-mentioned phenothiazine self-assembled organic small molecule hole transport material in the fabrication of perovskite solar cell devices.

[0024] The present invention has at least the following beneficial effects:

[0025] (1) This invention, based on a self-assembled monolayer design strategy, introduces carboxylic acid anchoring groups and bridging units into phenothiazine molecules to synthesize novel phenothiazine self-assembled organic small molecule hole transport materials. This molecular structure design not only adjusts the molecular energy levels of the hole transport material but also improves the interfacial contact of the hole transport layer in perovskite solar cells. When this material is used in inverted perovskite solar cell devices, the carboxylic acid anchoring groups can form chemical bonds with the hydroxyl groups of the glass conductive substrate, forming a directionally aligned self-assembled layer on the surface of the glass conductive substrate to enhance charge transport capability and improve photoelectric conversion efficiency. Furthermore, when assembling perovskite solar cell devices using this type of material, there is no need to dope with lithium salts, and the battery devices exhibit high water and oxygen stability.

[0026] (2) The phenothiazine self-assembled organic small molecule hole transport material provided by the present invention has a simple synthesis process and the raw materials are cheap and readily available. Therefore, it has great practical application value and provides a new material option for the development of high-performance perovskite solar cells. Attached Figure Description

[0027] Figure 1 The 1H NMR spectrum of the phenothiazine self-assembled organic small molecule hole transport material BS in the examples is shown.

[0028] Figure 2 The carbon NMR spectrum of BS, a phenothiazine self-assembled organic small molecule hole transport material, is shown in the example.

[0029] Figure 3 The 1H NMR spectrum of the phenothiazine self-assembled organic small molecule hole transport material BD in the examples is shown.

[0030] Figure 4 The carbon NMR spectrum of the phenothiazine self-assembled organic small molecule hole transport material BD in the examples is shown.

[0031] Figure 5 The 1H NMR spectrum of the phenothiazine self-assembled organic small molecule hole transport material SN in the examples is shown.

[0032] Figure 6 The carbon NMR spectrum of the phenothiazine self-assembled organic small molecule hole transport material SN in the examples is shown.

[0033] Figure 7 The UV-Vis absorption spectrum of the phenothiazine self-assembled organic small molecule hole transport material in the examples is shown.

[0034] Figure 8 The JV curves are for perovskite solar cell devices based on the aforementioned phenothiazine self-assembled organic small molecule hole transport material. Detailed Implementation

[0035] The technical solution of the present invention will be further explained and described below through specific embodiments.

[0036] Unless otherwise specified, the detection methods in the following embodiments are conventional detection methods; and the reagents in the following embodiments are commercially available unless otherwise specified.

[0037] Example 1

[0038] A self-assembled organic small molecule hole transport material (BS) of a monocarboxylic acid phenothiazine, with the following structural formula: Its preparation method includes the following steps:

[0039] (1) Synthesis of intermediate (I): At room temperature, phenothiazine (0.5 g, 2.51 mmol), ethyl 4-bromobenzoate (0.69 g, 3 mmol), tri-tert-butylphosphine tetrafluoroborate (0.073 g, 0.25 mmol), tris(dibenzylacetone)dipalladium (0.11 g, 0.12 mmol), and sodium tert-butoxide (0.48 g, 5 mmol) were added sequentially to a two-necked flask. 15 mL of dry toluene was added under an argon atmosphere, and the mixture was refluxed at 110 °C for 16 h. After the reaction was complete, the mixture was cooled to room temperature, and the reaction solution was poured into deionized water and extracted with ethyl acetate. The extracted organic phase was dried over anhydrous sodium sulfate and filtered. The filtrate was subjected to rotary evaporation to remove the solvent, yielding the crude product. The crude product was purified by column chromatography (PE:EA = 30:1) to obtain the yellow intermediate (I) in 86% yield. 1 H NMR(400MHz,Chloroform-d)δ8.08(d,J=8.8Hz,2H),7.25(d,J=5.7Hz,4H),7.17–6. 91(m,4H),6.77(dd,J=8.0,1.4Hz,2H),4.38(q,J=7.1Hz,2H),1.39(t,J=7.1Hz,3H).

[0040] (2) Synthesis of phenothiazine monocarboxylic acid self-assembled organic small molecule hole transport material (BS): At room temperature, intermediate (Ⅰ) (0.48 g, 1.38 mmol) and 15 ml tetrahydrofuran were added to a single-necked flask. 15 ml of 3% sodium hydroxide aqueous solution was added dropwise to the single-necked flask with stirring, and then the reaction was carried out overnight at 70 °C. After the reaction was completed, the tetrahydrofuran was removed by rotary evaporation, and 3% hydrochloric acid aqueous solution was added dropwise to the aqueous phase until pH=2. The product precipitated, filtered, and dried in a vacuum drying oven for 12 h to obtain a white compound (BS) in 93% yield. 1 H NMR (400MHz, DMSO-d6), Figure 1)δ7.99(d,J=8.6Hz,2H),7.33(dd,J=7.7,1.5Hz,2H),7.25(d,J=8.7Hz,2H),7.18(dd,J=7.8,1.6Hz,2H),7.10(d,J=7.5Hz,2H),6.85(d,J=8.0Hz,2H). 13 C NMR (101MHz, DMSO-d6, Figure 2 )δ166.85,146.74,141.98,131.62,127.88,127.68,126.83,126.48,124.86,122.43,121.76.HRMS-ESI(m / z):[M+H] + Calcd for(C 19 H 13 NO2S): 320.0701, found: 320.0740.

[0041] Example 2

[0042] A self-assembled organic small molecule hole transport material (BD) of dicarboxylic acid phenothiazine, with the following structural formula: Its preparation method includes the following steps:

[0043] (1) Synthesis of intermediate (II): At room temperature, phenothiazine (0.5 g, 2.51 mmol), dimethyl 5-bromoisophthalate (0.82 g, 3 mmol), tri-tert-butylphosphine tetrafluoroborate (0.073 g, 0.25 mmol), tris(dibenzylacetone)dipalladium (0.11 g, 0.12 mmol), and sodium tert-butoxide (0.48 g, 5 mmol) were added sequentially to a two-necked flask. 15 mL of dry toluene was added under an argon atmosphere, and the mixture was refluxed at 110 °C for 16 h. After the reaction was complete, the mixture was cooled to room temperature, and the reaction solution was poured into deionized water and extracted with ethyl acetate. The extracted organic phase was dried over anhydrous sodium sulfate and filtered. The filtrate was evaporated by rotary evaporation to remove the solvent, yielding the crude product. The crude product was separated by column chromatography (PE:EA = 25:1) to obtain yellow intermediate (II) in 48% yield. 1 H NMR(500MHz,Chloroform-d)δ8.70(s,1H),8.23(d,J=1.6Hz,2H),7.13(dd,J=7.5,1.7 Hz, 2H), 6.93 (ddd, J=11.8, 7.5, 1.6Hz, 4H), 6.35 (dd, J=8.0, 1.3Hz, 2H), 3.95 (s, 6H).

[0044] (2) Synthesis of self-assembled organic small molecule hole transport material (BD) of dicarboxylic acid phenothiazine: At room temperature, intermediate (II) (0.39 g, 1 mmol) and 15 ml tetrahydrofuran were added to a single-necked flask. 15 ml of 3% sodium hydroxide aqueous solution was added dropwise to the single-necked flask with stirring, and the reaction was allowed to proceed overnight at room temperature. After the reaction was completed, the tetrahydrofuran was removed by rotary evaporation. 3% hydrochloric acid aqueous solution was added dropwise to the aqueous phase until pH=2, and the product precipitated. The product was filtered and dried in a vacuum drying oven for 12 h to obtain a yellow-green compound (BD) in 92% yield. 1 H NMR (500MHz, DMSO-d6), Figure 3 )δ8.39(s,1H),7.96(d,J=1.5Hz,2H),7.29(dd,J=7.7,1.5Hz,2H),7.13(dd, J=8.0,1.6Hz,2H),7.07(dd,J=7.5,1.3Hz,2H),6.66(dd,J=8.1,1.2Hz,2H). 13 C NMR (101MHz, DMSO-d6, Figure 4 )δ166.06,142.96,142.37,133.72,129.83,127.72,127.66,127.22,124.61,124.47,120.16.HRMS-ESI(m / z):[M+H] + Calcd for(C 20 H 13 NO4S):364.0565,found:364.0457.

[0045] Example 3

[0046] A self-assembled organic small molecule hole transport material (SN) of an alkyl carboxylic acid phenthiazine, with the following structural formula:

[0047]

[0048] Alkyl carboxylic acid phenothiazine organic small molecule hole transport materials (SN): 1 H NMR (500MHz, Chloroform-d, Figure 5 )δ7.25–7.10(m,4H),6.99–6.85(m,4H),4.23(t,J=7.4Hz,2H),2.96–2.87(m,2H). 13 CNMR (126MHz, Chloroform-d, Figure 6)δ177.54,144.73,127.81,127.54,125.62,123.07,115.39,42.55,32.36.HRMS-ESI(m / z):[M+H] + Calcd for(C 15 H 13 NO2S):272.0701,found:272.0728.

[0049] Performance testing

[0050] (1) The UV-Vis absorption spectrum of the phenothiazine self-assembled organic small molecule hole transport material is shown in [reference needed]. Figure 7 The results show that the phenothiazine self-assembled organic small molecule hole transport material does not have strong absorption in the visible light region, indicating that the phenothiazine self-assembled organic small molecule hole transport material does not compete with perovskite for light.

[0051] (2) The phenothiazine self-assembled organic small molecule hole transport material prepared in Examples 1 to 3 was applied to perovskite solar cell devices. Its specific structure is: FTO / phenothiazine self-assembled organic small molecule hole transport material / perovskite active layer / electron transport layer / Ag.

[0052] The FTO glass was first ultrasonically washed with water, then sequentially cleaned with deionized water, acetone, and ethanol. After drying, a solution of phenothiazine self-assembled organic small molecule hole transport material was spin-coated onto the FTO glass surface and annealed. Next, a perovskite active layer and an electron transport layer were spin-coated. Finally, Ag was deposited as the back electrode, completing the fabrication of the perovskite solar cell device with an effective area of ​​0.12 cm². 2 .

[0053] Using a xenon lamp solar simulator, the light source intensity was tested at AM 1.5G (100mW / cm²). 2 The open-circuit voltage, short-circuit current, and fill factor of the fabricated solar cell device were tested. The perovskite solar cell device was fabricated and characterized according to the above procedure. The current-voltage (JV) characteristic curve of the perovskite solar cell device is shown below. Figure 8 As shown in the figure, the open-circuit voltage (Voc) of the battery based on the phenothiazine self-assembled organic small molecule hole transport material (BS) is 1.10V, and the short-circuit current (Jsc) is 24.41mA / cm. 2 The fill factor (FF) was 77.59%, and the power conversion efficiency (PCE) was 20.82%. The open-circuit voltage (Voc) of the battery based on phenothiazine self-assembled organic small molecule hole transport material (BD) was 1.09V, and the short-circuit current (Jsc) was 24.98mA / cm². 2The fill factor (FF) was 77.46%, and the power conversion efficiency (PCE) was 21.08%. The open-circuit voltage (Voc) of the battery based on phenothiazine self-assembled organic small molecule hole transport material (SN) was 1.10V, and the short-circuit current (Jsc) was 25.16mA / cm². 2 The fill factor (FF) is 80.85%, and the power conversion efficiency (PCE) is 22.31%. The open-circuit voltage (Voc) of the perovskite solar cell device based on the widely used phosphonate-carbazole organic small molecule MeO-2PACz as the hole transport material is 1.12V, and the short-circuit current (Jsc) is 25.70mA / cm². 2 The fill factor (FF) is 76.68% and the PCE is 22.05%. These results demonstrate that perovskite solar cell devices using phenothiazine self-assembled organic small molecule hole transport materials as hole transport materials exhibit excellent electrochemical performance.

[0054] The above are merely preferred embodiments of the present invention, and therefore should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made in accordance with the scope of the patent and the contents of the specification should still fall within the scope of the present invention.

Claims

1. The application of a phenothiazine self-assembled organic small molecule hole transport material in the fabrication of perovskite solar cell devices, characterized in that, The general structural formula of the phenothiazine self-assembled organic small molecule hole transport material is as follows: ; Where n = 1 to 5.

2. The application as described in claim 1, characterized in that, The phenothiazine self-assembled organic small molecule hole transport material has the following structural formula: .

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