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

Abstract

The invention discloses a phenothiazine self-assembled small organic molecule hole transport material and application thereof, the phenothiazine self-assembled small organic molecule hole transport material has the following structural general formula: # imgabs0 #, R is # imgabs1 #, and n is 1-5. According to the phenothiazine self-assembled small organic molecule hole transport material disclosed by the invention, based on a self-assembled monomolecular layer design strategy, a carboxylic acid anchoring group and different bridging units are introduced into a phenothiazine molecular structure, so that the molecular energy level of the hole transport material is adjusted, and the interface contact of a hole transport layer is improved. When the material is used as a non-doped hole transport layer to be applied to a perovskite solar cell device, the material shows good photoelectric conversion efficiency. More importantly, the synthesis process is simple and convenient, and the raw materials are wide in source and low in price, so that the material is more competitive in practical application, and a new breakthrough is expected to be brought to the development of perovskite solar cells.

Description

Technical Field

[0001] The invention relates to the technical field of optoelectronic materials, and in particular to a phenothiazine self-assembled organic small molecule hole transport material and application thereof. Background Art

[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 crystalline silicon-based solar cells and has great development potential.

[0003] Perovskite solar cell devices are mainly composed of transparent conductive glass, electron transport layer, perovskite active layer, hole transport layer and conductive electrode (metal or conductive metal oxide). The structure of solar cell devices can be divided into positive structure (nip) and inverted structure (pin). Among them, the inverted device has the characteristics of better stability, small hysteresis effect, low temperature preparation and applicability to flexible substrates, and has good commercial application prospects. The hole transport layer is an important component of perovskite solar cell devices. In addition to the extraction and transmission of holes, the hole transport layer can also passivate the defects of the perovskite layer and protect the perovskite layer from moisture and oxygen in the external environment. Hole transport materials can be divided into inorganic (NiO, CuI, CuSCN, etc.), organic polymers (PTAA, PEDOT: PSS, P3HT, etc.) and organic small molecules (Spiro-OMeTAD, 2PACz, etc.) according to their types. Compared with inorganic hole transport materials, the biggest feature of organic hole transport materials is that they can achieve energy level regulation and molecular empowerment through molecular design modification. The mainstream hole transport materials used in inverted devices are polymer PTAA and PEDOT:PSS, but they are expensive, require dopants to improve the hole mobility of the material, and the material itself is corrosive and hygroscopic, which will destroy the perovskite layer and affect the stability of the battery, limiting their large-scale application. In addition, the transparent conductive glass used in the preparation of perovskite solar cell devices needs to be annealed at high temperature after sputtering deposition, and the surface roughness is large, making it difficult to control the surface composition and work function, which is not conducive to charge transfer at the interface. Summary of the invention

[0004] The purpose of the present invention is to provide a phenothiazine self-assembled organic small molecule hole transport material and its application. The phenothiazine self-assembled organic small molecule hole transport material is used in a perovskite battery to improve the charge transfer capacity and photoelectric conversion efficiency of the perovskite battery.

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

[0006] A phenothiazine self-assembled organic small molecule hole transport material, the general structural formula of which is

[0007]

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

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

[0010]

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

[0012] A phenothiazine self-assembled organic small molecule hole transport material, the general structural formula of which is

[0013]

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

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

[0016]

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

[0018] A phenothiazine self-assembled organic small molecule hole transport material, the general structural formula of which is

[0019]

[0020] Among them, n=1~5.

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

[0022]

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

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

[0025] (1) Based on the self-assembled monolayer design strategy, the present invention introduces carboxylic acid anchoring groups and bridging units into the phenothiazine molecule to synthesize a new type of phenothiazine self-assembled organic small molecule hole transport material. This molecular structure design can not only adjust the molecular energy level of the hole transport material, but also improve the interface contact of the hole transport layer in the perovskite solar cell. When the material is used in an inverted perovskite solar cell device, the carboxylic acid anchoring group can form a chemical bond with the hydroxyl group of the glass conductive substrate to form a directional self-assembled layer on the surface of the glass conductive substrate to enhance the charge transfer capability and improve the photoelectric conversion efficiency. Furthermore, when using this type of material to assemble a perovskite solar cell device, there is no need to dope lithium salts, and the battery device has a high water-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 easily available, so it has good practical application value and provides a new material option for the development of high-performance perovskite solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the nuclear magnetic resonance hydrogen spectrum of the phenothiazine self-assembled organic small molecule hole transport material BS in the example;

[0028] Figure 2 The carbon nuclear magnetic resonance spectrum of the phenothiazine self-assembled organic small molecule hole transport material BS in the embodiment;

[0029] Figure 3 This is the nuclear magnetic resonance hydrogen spectrum of the phenothiazine self-assembled organic small molecule hole transport material BD in the example;

[0030] Figure 4 The carbon nuclear magnetic resonance spectrum of the phenothiazine self-assembled organic small molecule hole transport material BD in the embodiment;

[0031] Figure 5 The nuclear magnetic resonance hydrogen spectrum of the phenothiazine self-assembled organic small molecule hole transport material SN in the embodiment;

[0032] Figure 6 The carbon nuclear magnetic resonance spectrum of the phenothiazine self-assembled organic small molecule hole transport material SN in the embodiment;

[0033] Figure 7 The UV-visible absorption spectrum of the phenothiazine self-assembled organic small molecule hole transport material in the embodiment;

[0034] Figure 8 This is the JV curve of the perovskite solar cell device based on the above-mentioned phenothiazine self-assembled organic small molecule hole transport material. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is further illustrated and described below through specific implementation methods.

[0036] In the following examples, unless otherwise specified, the detection methods in the following examples are conventional detection methods; the reagents in the following examples are purchased from commercial channels unless otherwise specified.

[0037] Example 1

[0038] A monocarboxylic acid phenothiazine self-assembled organic small molecule hole transport material (BS) having the structural formula: The preparation method thereof comprises 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), tri(dibenzylideneacetone)dipalladium (0.11 g, 0.12 mmol), sodium tert-butoxide (0.48 g, 5 mmol) were added to a two-necked flask in sequence, and 15 ml of dry toluene was added under an argon atmosphere, followed by reflux at 110°C for 16 h. After the reaction was completed, the mixture was cooled to room temperature, and then the reaction solution was poured into deionized water and extracted with ethyl acetate. The organic phase obtained by the extraction was dried over anhydrous sodium sulfate and filtered, and the obtained filtrate was subjected to rotary evaporation to remove the solvent to obtain a crude product; the crude product was purified by column chromatography (PE:EA=30:1) to obtain a yellow intermediate (I) with a yield of 86%; 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 self-assembled organic small molecule hole transport material (BS) of monocarboxylic acid: At room temperature, intermediate (I) (0.48 g, 1.38 mmol) and 15 ml of tetrahydrofuran were added to a single-necked bottle, and 15 ml of a 3% aqueous sodium hydroxide solution was added dropwise to the single-necked bottle under stirring, followed by overnight reaction at 70°C; after the reaction, the tetrahydrofuran was removed by rotary evaporation, and a 3% aqueous hydrochloric acid solution was added dropwise to the aqueous phase until the pH value was 2, the product precipitated, filtered, and dried in a vacuum drying oven for 12 h to obtain a white compound (BS) with a yield of 93%; 1 H NMR (400 MHz, 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 (101 MHz, 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 dicarboxylic acid phenothiazine self-assembled organic small molecule hole transport material (BD) having the structural formula The preparation method thereof comprises 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), tri(dibenzylideneacetone)dipalladium (0.11 g, 0.12 mmol), sodium tert-butoxide (0.48 g, 5 mmol) were added to a two-necked flask in sequence, and 15 ml of dry toluene was added under an argon atmosphere, followed by reflux at 110°C for 16 h. After the reaction was completed, the mixture was cooled to room temperature, and then the reaction solution was poured into deionized water and extracted with ethyl acetate. The organic phase obtained by the extraction was dried over anhydrous sodium sulfate and filtered. The obtained filtrate was subjected to rotary evaporation to remove the solvent to obtain a crude product; the crude product was separated by column chromatography (PE:EA=25:1) to obtain a yellow intermediate (II) with a yield of 48%; 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 phenothiazine self-assembled organic small molecule hole transport material (BD) of dicarboxylic acid: At room temperature, intermediate (II) (0.39 g, 1 mmol) and 15 ml of tetrahydrofuran were added to a single-necked bottle, and 15 ml of a 3% aqueous sodium hydroxide solution was added dropwise to the single-necked bottle under stirring, followed by overnight reaction at room temperature; after the reaction, the tetrahydrofuran was removed by rotary evaporation, and a 3% aqueous hydrochloric acid solution was added dropwise to the aqueous phase until the pH value was 2, the product precipitated, filtered, and dried in a vacuum drying oven for 12 h to obtain a yellow-green compound (BD) with a yield of 92%; 1 H NMR (500 MHz, 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 (101 MHz, 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 phenothiazine self-assembled organic small molecule hole transport material (SN) of alkyl carboxylic acid, the structural formula of which is

[0047]

[0048] Alkyl carboxylic acid phenothiazine organic small molecule hole transport material (SN): 1 H NMR (500 MHz, 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-visible absorption spectrum of phenothiazine self-assembled organic small molecule hole transport materials is shown in Figure 7 , showing that phenothiazine self-assembled organic small molecule hole transport materials have no strong absorption in the visible light region, indicating that phenothiazine self-assembled organic small molecule hole transport materials will not compete with perovskite for light.

[0051] (2) The phenothiazine self-assembled organic small molecule hole transport material prepared in Examples 1 to 3 is applied to a perovskite solar cell device, and 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 cleaned with deionized water, acetone and ethanol in turn. After drying, a solution of phenothiazine self-assembled organic small molecule hole transport material was spin-coated on the FTO glass surface using a spin coater and annealed. The perovskite active layer and electron transport layer were then spin-coated. Finally, Ag was evaporated as the back electrode to complete the preparation of the perovskite solar cell device. The effective area of ​​the device was 0.12 cm 2 .

[0053] Use a xenon lamp solar simulator and test the light source intensity to be AM 1.5G (100mW / cm 2 ), the open circuit voltage, short circuit current and fill factor of the prepared battery device were tested. The perovskite solar cell device was prepared and characterized according to the above procedure. The current-voltage (JV) characteristic curve of the perovskite solar cell device is shown in Figure 8 Among them, the open circuit voltage (Voc) of the battery based on 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) is 77.59%, the photoelectric conversion efficiency (PCE) is 20.82%; the open circuit voltage (Voc) of the battery based on phenothiazine self-assembled organic small molecule hole transport material (BD) is 1.09V, and the short circuit current (Jsc) is 24.98mA / cm 2, the fill factor (FF) is 77.46%, the photoelectric conversion efficiency (PCE) is 21.08%; the open circuit voltage (Voc) of the battery based on phenothiazine self-assembled organic small molecule hole transport material (SN) is 1.10V, and the short circuit current (Jsc) is 25.16mA / cm 2 , the fill factor (FF) is 80.85%, and the photoelectric conversion efficiency (PCE) is 22.31%; the open circuit voltage (Voc) of the perovskite solar cell device based on the widely used phosphonic acid carbazole organic small molecule MeO-2PACz as the hole transport material is 1.12V, and the short circuit current (Jsc) is 25.70mA / cm 2 , the fill factor (FF) is 76.68%, and the PCE is 22.05%. The above results show that the perovskite solar cell device with phenothiazine self-assembled organic small molecule hole transport material as hole transport material has good electrochemical performance.

[0054] The above are only preferred embodiments of the present invention, and therefore cannot be used to limit the scope of implementation of the present invention. That is, equivalent changes and modifications made according to the patent scope of the present invention and the contents of the specification should still fall within the scope of the present invention.

Claims

1. A phenothiazine self-assembled organic small molecule hole transport material, characterized in that: Its general structural formula is Wherein, R1 and R2 are independently selected from One of them.

2. The phenothiazine self-assembled organic small molecule hole transport material according to claim 1, characterized in that: Its structural formula is 3. Use of the phenothiazine self-assembled organic small molecule hole transport material according to claim 1 or 2 in the preparation of a perovskite solar cell device.

4. A phenothiazine self-assembled organic small molecule hole transport material, characterized in that: Its general structural formula is Wherein R3 and R4 are independently selected from One of them.

5. The phenothiazine self-assembled organic small molecule hole transport material according to claim 4, characterized in that: Its structural formula is 6. Use of the phenothiazine self-assembled organic small molecule hole transport material according to claim 3 or 4 in the preparation of a perovskite solar cell device.

7. A phenothiazine self-assembled organic small molecule hole transport material, characterized in that: Its general structural formula is Among them, n=1~5.

8. The phenothiazine self-assembled organic small molecule hole transport material according to claim 7, characterized in that: Its structural formula is 9. Use of the phenothiazine self-assembled organic small molecule hole transport material according to claim 7 or 8 in the preparation of a perovskite solar cell device.

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