Patent Publication Number: US-2022231242-A1

Title: Composite interface transport material-based perovskite photovoltaic, light emission and light detection multi-functional device and preparation method therefor

Description:
TECHNICAL FIELD 
     The present invention belongs to the photoelectric field of perovskite, and particularly relates to a composite interface transport material-based perovskite photovoltaic, light emission and light detection multi-functional device and a preparation method thereof. 
     DESCRIPTION OF RELATED ART 
     In recent years, organic/inorganic halide perovskite materials have lots of advantages, such as, high light absorption coefficient, long carrier lifetime, adjustable bandgap and low cost, and thus become the research focus in the photoelectric field. The solar cell and light emitting diode based on the material have achieved great progress, and gradually exhibited good application prospect. According to the statistics of the National Renewable Energy Laboratory (NREL), the maximum certified power conversion efficiency of the perovskite solar cell has been up to 23.7%. It is reported by the latest Nature that the external quantum efficiency of perovskite light-emitting diode has been over 20%. Moreover, the device may achieve light detection functions, and it is a greatly significant research topic whether multiple functions may be combined, that is, multiple functions are achieved in a device, so as to prepare a perovskite multi-functional device possessing photovoltaic properties, light emission and light detection, such that the multi-functional device can sensitively respond to optical signal to achieve high-efficiency power generation under solar illumination and low-energy light emission in the dark. 
     Perovskite solar cell and light emitting diode have the similar device structure, but they have reverse energy conversion process under working conditions.  FIG. 2 b    and  FIG. 2 c    compare the energy band configuration of a solar cell ( FIG. 2 b   ) and a light emitting diode ( FIG. 2 c   ). Solar cells are arranged in a form of staggered energy band, that is, the conduction band of a perovskite active layer is higher than the conduction band of an electron transport layer (the lowest unoccupied molecular orbital), and the valence band is lower than the valence band of a hole transport layer (the highest occupied molecular orbital), as shown in  FIG. 2 b   . Such kind of energy band structure is beneficial to the effective extraction of photon-generated carriers in the active layer into the electron transport layer and the hole transport layer. Light emitting diodes are arranged in a form of crossover energy band, that is, the conduction band of a perovskite active layer is lower than the conduction band of an electron transport layer (the lowest non-occupied molecular orbital), and the valence band is higher than the valence band of a hole transport layer (the highest occupied molecular orbital), as shown in  FIG. 2 c   . Such kind of energy band structure is beneficial to the injection of charges to the perovskite active layer from the electron transport layer and the hole transport layer, thereby achieving radiative recombination light emission in the active layer. For a photo-detector, dark current needs to be reduced and so on. Therefore, such two kinds of devices demand for the not exactly same energy band configuration from the aspect of energy band configuration. The preparation of a multi-functional perovskite device integrated with high photoelectric conversion efficiency, high electroluminescence efficiency and high detection sensitivity becomes a challenge. 
     SUMMARY 
     Technical Problem 
     Since the solar cells, light emitting diodes and photoelectric detectors based on heterogeneous structure have different energy band configuration modes of each functional layer in different devices, it is difficult to achieve high-performance photovoltaic properties, light emission and light detection performance in a same device at the same time. The present invention aims at proposing a composite interface transport material-based perovskite photovoltaic, light emission and light detection multi-functional device and a preparation method thereof, thus eliminating a potential barrier between the perovskite active layer and the transport layer via energy-band engineering, and an energy band structure is designed, as shown in  FIG. 2 a   . The energy band structure may simultaneously and effectively improve the photovoltaic efficiency, luminous efficiency and light detection sensitivity of the perovskite multi-functional device. 
     Solutions for the Problem 
     Technical Solution 
     The objective of the present invention is achieved by one of the following technical solutions. 
     Provided is a composite interface transport material-based perovskite photovoltaic, light emission and light detection multi-functional device, and the multi-functional device comprises a transparent conductive glass, a composite electron transport layer, a perovskite active layer, a composite hole transport layer and a metal electrode layer which are sequentially arranged in a stacked manner from bottom to top. 
     Further, the transparent conductive electrode layer is an ITO or FTO transparent conductive glass; specifically, the transparent conductive electrode has a square resistance of 8-15Ω, a light transmittance of 85-90%, and the transparent conductive glass has a thickness of 1.1-2.2 mm. 
     Further, the metal electrode layer is gold, silver, copper or aluminum. Specifically, the metal electrode layer is deposited on the hole transport layer by thermal evaporation and has a thickness of 0.1-1000 nm. 
     Further, the composite electron transport layer has a thickness of 5-120 nm; the composite electron transport layer is a SnO 2 (Cl):GQDs or TiO 2 (Cl):GQDs film, specifically, including an amino-graphene quantum dot and further including stannic oxide or titanium dioxide prepared from a chlorine salt, and a mass ratio of the chlorine salt to the amino-graphene quantum dot ranges from 10:1 to 1000:1. The stannic oxide or titanium dioxide prepared from a chlorine salt refers to SnO 2  or TiO 2  containing partial Cl residues. Moreover, the composite electron transport layer has a thickness of 5-120 nm. 
     Further, the perovskite active layer is one or more of CH 3 NH 3 PbX 3 , NH 2 CH 2 NH 3 PbX 3  or CsPbX 3 , and X is I or Br; and the perovskite active layer has a thickness of 50-600 nm. 
     Further, the composite hole transport layer is spiro-OMeTAD:FN—Br composited by tetra[N,N-bi(4-methoxy phenyl)amino]-9,9′-spiro-OMeTAD and 2,7-dibromo-9,9-bis[3-(dimethylamino)propyl]fluorene (FN—Br), and a mass ratio of spiro-OMeTAD to FN—Br is 10-1000:1, and the composite hole transport layer has a thickness of 20-200 nm. 
     Further, FN—Br can be replaced by TFB or F8BT which have a work function greater than 5.4 eV. 
     The present invention further provides a preparation method of the above multi-functional device, including the following steps: 
     (1) Cleaning of the Transparent Conductive Glass 
     Performing ultrasonic cleaning on a conductive glass, drying the conductive glass with nitrogen or compressed air, then performing surface cleaning treatment by an ultraviolet light to remove organic matters and enhance film-forming property; 
     (2) Preparation of the Composite Electron Transport Layer 
     Preparing a precursor solution from stannous chloride, stannic chloride or titanium tetrachloride, then adding amino-graphene quantum dots for mixing, and spin coating a mixed solution on the transparent conductive glass, then performing heat treatment, and performing ultraviolet ozonation treatment after cooling, where a dangling bond formed by the ultraviolet ozonation treatment could enhance the subsequent film-forming property; 
     (3) Preparation of the Perovskite Active Layer 
     spin coating a perovskite precursor solution on the composite electron transport layer, and dropwise adding an antisolvent for continuous spin coating when the solvent is wet, and performing heat treatment on the spin coated perovskite film; 
     (4) Preparation of the Composite Hole Transport Layer 
     Spin coating a mixed solution of spiro-OMeTAD and FN—Br on a surface of the perovskite active layer; 
     (5) Preparation of a Metal Electrode 
     Evaporating gold or silver on the composite hole transport layer under vacuum conditions to obtain the perovskite-based photovoltaic, light-emitting and light detection multi-functional device. 
     Further, in the step (1), the conductive glass is subjected to ultrasonic cleaning for 5-10 min successively in deionized water, a liquid detergent, acetone and an ethanol solution, then the ITO or FTO conductive glass is dried by nitrogen or compressed air, and treated for 10-30 min by an UV-ozone cleaner. 
     Further, in the step (2), specifically, the mixed solution is coated on a substrate of the transparent conductive glass for 30-60 s at a rotary speed of 2000-5000 rpm. Finally, the spin-coated film is put on a hot plate and heated for 0.5-2 h at 180-270° C., cooled and put to ultraviolet ozone to be treated for 5-15 min; a solvent of the mixed solution is ethanol, stannous chloride or stannic chloride has a concentration of 0.1%-10 wt %, and the amino-graphene quantum dot has a concentration of 0.01-1 wt %. 
     Further, in the step (3), PbI 2 , NH 2 CH 2 NH 3 I (or CH 3 NH 3 I, and the like) and DMSO are dissolved into a DMF solution according to a molar ratio of 1:1:1, and the concentration is 1.25-1.6 mol/ml. After dissolving, the perovskite precursor solution is dropped on the composite electron transport layer for spin coating at 3000-5000 rpm, and 100-1000 μL diethyl ether is added dropwise at 20-25 s. The spin-coated perovskite film is put on a 100-120° C. hot plate for heat treatment for 5-30 min. 
     Further, in the step (4), the mixed solution of spiro-OMeTAD and FN—Br is obtained by dissolving spiro-OMeTAD and FN—Br powder into chlorobenzene, and spiro-OMeTAD has a mass concentration of 1-10 wt %, and FN—Br has a mass concentration of 0.01-1 wt %. Moreover, spin coating conditions are as follows: spin coating is performed for 35-60 s at a rotary speed of 3000-5000 rpm. 
     Further, the antisolvent is methylbenzene, chlorobenzene or diethyl ether. 
     The energy band configuration of the composite electron transport layer, the perovskite active layer and the composite hole transport layer in the present invention is shown in  FIG. 2 a   , and the specific control idea is shown in  FIG. 3 ; and the core idea is to utilize an electron transport material with a greater work function to be matched with an electron transport material with a small work function, thus obtaining levelled quasi-fermi level with the perovskite conduction band, and eliminating the charge transfer potential barrier on the contact interface between the composite electron transport layer and the perovskite luminous layer, namely, making the electron transfer potential barrier on the contact interface zero (see the dashed box in  FIG. 3 ); electrons may be not only injected into a perovskite layer, but also extracted, and the potential barrier on the electron and hole transfer interface is zero, which may achieve charge injection and extraction. Further, a hole transport material (e.g., FN—Br) with a larger work function may be utilized to be matched with a hole transport material (e.g., spiro-OMeTAD) with a small work function, and the work function of the composite material is adjusted to be levelled with the quasi-fermi level of the perovskite valence band, thus eliminating the charge transfer potential barrier on the contact interface between the composite electron transport layer and the perovskite luminous layer, that is, making the hole transfer potential barrier on the contact interface zero (see the dashed box in  FIG. 3 ), and holes may be not only injected into a perovskite layer, but also extracted. The composite electron transport layer and composite hole transport layer composited by a plurality of transport materials are matched with a perovskite active layer to obtain a perovskite multi-functional device with high overall performance, such that the device forms an energy band structure configuration close to zero charge transfer potential barrier as shown in  FIG. 2 a   , thus inhibiting nonradiative recombination, and finally substantially improving the photoelectric conversion efficiency, luminous efficiency and light detection performance of the perovskite multi-functional device. 
     Beneficial Effects of the Invention 
     Beneficial Effects 
     Compared with the prior art, the present invention has the following beneficial effects: 
     compared with the conventional perovskite solar cell and light emitting diode, what is different in the present invention is to achieve the charge injection into an active layer under external voltage and to achieve charge extraction from the active layer under light illumination by eliminating an energy band potential barrier between a perovskite active layer and a transport layer, thereby preparing a perovskite multi-functional device integrated with high photoelectric conversion efficiency, high luminous efficiency and high detection sensitivity. 
     The key technology is to utilize composite electrons/hole materials to achieve energy band control; multi-element electron transport materials are respectively doped and composited with hole transport materials to effectively control the work functions of the electron transport layer and the hole transport layer, thus effectively eliminating the interface potential barrier between perovskite and the transport layer, and inhibiting the nonradiative recombination at the interface. According to experiment result comparisons, the photoelectric conversion efficiency (20.45%) and the luminous efficiency (EQE, 4.3%) of the perovskite multi-functional device, with energy band regulated, are significantly increased. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Description of the Drawings 
         FIG. 1  shows a structure diagram of a composite interface transport material-based perovskite photovoltaic, light emission and light detection multi-functional device in the present invention; 
         FIG. 2 a    shows a structural schematic diagram of an energy band of the perovskite multi-functional device in the present invention; 
         FIG. 2 b    shows a structural schematic diagram of an energy band of a solar cell; 
         FIG. 2 c    shows a structural schematic diagram of an energy band of a light emitting diode; 
         FIG. 3  is a diagram showing a structure and working principle of the perovskite multi-functional device in Example 1 of the present invention; 
         FIG. 4  shows an energy band diagram of an electron transport layer and a hole transport layer of the perovskite multi-functional device in Example 1 of the present invention; 
         FIG. 5  shows an I-V graph of the perovskite multi-functional device in Example 1 of the present invention under AM1.5 light illumination; 
         FIG. 6  shows a photoresponse diagram of the perovskite multi-functional device in Example 1 of the present invention under AM1.5 light illumination. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Detailed Description of the Embodiments 
     The present invention will be further described in detail with reference to the specific examples, which is used to explain the present invention, but not limited thereto. 
     Example 1 
     As shown in  FIG. 1 , a perovskite-based photovoltaic, light-emitting and light detection multi-functional device includes a transparent conductive glass, a composite electron transport layer, a perovskite active layer, a composite hole transport layer and a metal electrode layer which are sequentially arranged in a stacked manner from bottom to top. 
     A preparation method of the perovskite-based photovoltaic, light-emitting and light detection multi-functional device includes the following steps: 
     (1) Cleaning of an ITO glass: an ITO glass having a square resistance of 10Ω, light transmittance of 90% and a thickness of 1.1 mm was chosen, and subjected to ultrasonic cleaning for 5 min successively in deionized water, a liquid detergent, acetone and an ethanol solution, then the ITO glass was dried by nitrogen, and treated for 20 min by an UV-ozone cleaner. 
     (2) Preparation of the composite electron transport layer: 23 mg SnCl 2 ·2H 2 O and 0.4 mg amino-graphene quantum dots were dissolved into 1 mL ethanol solution (the amino-graphene quantum dot had a concentration of 0.05 wt %, stannous chloride had a concentration of 2.4 wt %, and a mass ratio of stannous chloride to the amino-graphene quantum dot was 190:4), after being dissolved fully, the solution was spin coated on an ITO substrate for 30 s at a rotary speed of 3000 rpm. Finally, the spin coated film was put on a hot plate and heated for 1 h at 230° C., after cooling, put to ultraviolet ozone to be treated for 5 min, thus forming the composite electron transport layer, and the composite electron transport layer had a thickness of 40 nm; 
     (3) Preparation of a perovskite film:PbI 2 , CH 3 NH 3 I and DMSO were dissolved into DMF according to a molar ratio of 1:1:1 to obtain a perovskite precursor solution having a concentration of 1.45 mol/ml. After fully dissolving, the perovskite precursor solution was dropped on SnO 2 . After spin coating was performed for 10 s at 1000 rpm, the rotary speed was increased to 5000 rpm, and 600 μL diethyl ether was dropwise added at 20-22 s. The spin-coated perovskite film was put on a 100° C. hot plate for heat treatment for 10 min. 
     (4) Preparation of the composite hole transport layer: 24 mg spiro-OMeTAD, 0.05 mg FK209 and 1 mg FN—Br powder were dissolved into 1 mL chlorobenzene solvent (spiro-OMeTAD had a mass concentration of 2.1%, FN—Br had a mass concentration of 0.09%, and a mass ratio of spiro-OMeTAD to FN—Br was 24:1). Finally, the spiro-OMeTAD mixed solution was dropped on a surface of the perovskite film, and spin coated for 35 s at a rotary speed of 3000 rpm, and the composite hole transport layer had a thickness of 60 nm; 
     (5) Preparation of a metal electrode:gold was evaporated on the spiro-OMeTAD film under a vacuum condition of 1.0×10 −3  Pa, and prepared into a metal electrode having a thickness of 100 nm; 
     The above steps were finished to obtain the perovskite-based photovoltaic, light-emitting and light detection multi-functional device. 
     The performance of the perovskite multi-functional device obtain in the example was shown in  FIG. 4 . (a) in  FIG. 4  shows an energy band diagram of the composite electron transport layer; (b) in  FIG. 4  shows an energy band diagram of the composite hole transport layer; after doping with amino-graphene quantum dots, the work function of the SnO 2  electron transport layer reduced to 4.25 eV from 4.45 eV. After doping with FN—Br, the work function of spiro-OMeTAD was increased to 5.1 eV from 4.5 eV. The reverse-scanning photoelectric efficiency of the multi-functional device was 21.54%, and the forward scanning result was 20.88%, as shown in  FIG. 5 . The luminous efficiency of the device before and after optimization was respectively 0.2% and 4.3%, as shown in (a) in  FIG. 6 , and (b) in  FIG. 6  was fluorescence emission spectrum of the multi-functional device, and the light emission peak position was 772 nm. 
     Example 2 
     In this example, the transparent electrode used was an FTO conductive glass. Other steps were the same as those in Example 1, and the reverse-scanning photoelectric efficiency was 20.8% and the forward scanning result was 20.2%. The luminous efficiency was 1.8%. 
     Example 3 
     A preparation method of a perovskite-based photovoltaic, light-emitting and light detection multi-functional device includes the following steps: 
     (1) Cleaning of an ITO glass: an ITO glass having a square resistance of 10Ω, light transmittance of 90% and a thickness of 1.1 mm was chosen, and subjected to ultrasonic cleaning for 5 min successively in deionized water, a liquid detergent, acetone and an ethanol solution, then the ITO glass was dried by nitrogen, and treated for 20 min by an UV-ozone cleaner. 
     (2) Preparation of the composite electron transport layer: 23 mg SnCl 2 ·2H 2 O and 0.5 mg amino-graphene quantum dots were dissolved into 1 mL ethanol solution (the amino-graphene quantum dot had a concentration of 0.06 wt %, stannous chloride had a concentration of 2.4 wt %, and a mass ratio of stannous chloride to the amino-graphene quantum dot was 38:1), after being dissolved fully, the solution was spin coated on an ITO substrate for 30 s at a rotary speed of 3000 rpm. Finally, the spin coated film was put on a hot plate and heated for 1 h at 200° C., after cooling, put to ultraviolet ozone to be treated for 5 min, and the composite electron transport layer had a thickness of 40 nm; 
     (3) Preparation of a perovskite film:PbI 2 , NH 2 CH 2 NH 3 I (or CH 3 NH 3 I, and the like) and DMSO were dissolved into a DMF solution according to a ratio of 1:1:1, and the concentration was 1.45 mol/ml. After the solution was dissolved fully, the perovskite precursor solution was dropped on SnO 2 . Spin coating was performed for 10 s at 1000 rpm, the rotary speed was increased to 5000 rpm, and 600 μL diethyl ether was dropwise added at 20-22 s. The spin-coated perovskite film was put on a 100° C. hot plate for heat treatment for 10 min. 
     (4) Preparation of the composite hole transport layer: 75 mg spiro-OMeTAD, 0.05 mg FK209 and 2 mg FN—Br powder were dissolved into 1 mL chlorobenzene solvent (spiro-OMeTAD had a mass concentration of 6.3%, FN—Br had a mass concentration of 0.17%, and a mass ratio of spiro-OMeTAD to FN—Br was 75:2). Finally, the Spiro-OMeTAD mixed solution was dropped on a surface of the perovskite film, and spin coated for 35 s at a rotary speed of 3000 rpm, and the composite hole transport layer had a thickness of 200 nm; 
     (5) Preparation of a metal electrode:gold was evaporated on the spiro-OMeTAD film under a vacuum condition of 1.0×10 −3  Pa, and prepared into a metal electrode having a thickness of 100 nm; 
     The above steps were finished to obtain the perovskite-based photovoltaic, light-emitting and light detection multi-functional device. 
     The reverse-scanning photoelectric efficiency of the perovskite multi-functional device obtained in this example was 20.7%, and forward scanning result was 20.4%. The luminous efficiency was 4.2%. 
     Example 4 
     In this example, SnO 2  heat treatment temperature was 230° C. Other steps were the same as those in Example 3, the reverse-scanning photoelectric efficiency of the perovskite multi-functional device obtained in this example was 21.1%, and forward scanning result was 20.7%, and the luminous efficiency was 2.9%. 
     Example 5 
     In this example, 75 mg spiro-OMeTAD, 0.05 mg FK209 and 0.75 mg FN—Br powder were dissolved into 1 mL chlorobenzene solvent (through calculation, spiro-OMeTAD had a mass concentration of 6.3%, FN—Br had a mass concentration of 0.063%, and a mass ratio of spiro-OMeTAD to FN—Br was 100:1). Other steps were the same as those in Example 3, the reverse-scanning photoelectric efficiency of the perovskite multi-functional device obtained in this example was 21.3%, and forward scanning result was 20.1%, and the luminous efficiency was 2.2%. 
     Example 6 
     In this example, 10 mg amino-graphene quantum dots and 100 mg stannous chloride were dissolved into 1 mL ethanol solution. 2 mg FN—Br and 100 mg spiro-OMeTAD were dissolved into 1 mL chlorobenzene (through calculation, the amino-graphene had a concentration of 0.01 wt %, stannous chloride had a concentration of 0.1 wt %, and a mass ratio of stannous chloride to the amino-graphene quantum dots was 10:1, FN—Br had a concentration of 0.16 wt %, spiro-OMeTAD had a concentration of 8.3 wt %, and a mass ratio of spiro-OMeTAD to FN—Br was 50:1). Other steps were the same as those in Example 3, the reverse-scanning photoelectric efficiency of the perovskite multi-functional device obtained in this example was 20.4%, and the forward scanning result was 19.6%, and the luminous efficiency was 2.8%. 
     Example 7 
     In this example, 0.09 mg amino-graphene quantum dots and 910 mg stannous chloride were dissolved into 1 mL ethanol solution, and 12.3 mg FN—Br and 123 mg spiro-OMeTAD were dissolved into 1 mL chlorobenzene (through calculation, in this example, the amino-graphene had a concentration of 0.01 wt %, stannous chloride had a concentration of 10 wt, and a mass ratio of the two was 1:1000, spiro-OMeTAD had a concentration of 10 wt %, FN—Br had a concentration of 1 wt %, and a mass ratio of the two was 10:1); other steps were the same as those in Example 3. The reverse-scanning photoelectric efficiency of the perovskite multi-functional device obtained in this example was 20.1%, and the forward scanning result was 19.3%, and the light-emitting external quantum efficiency was 2.1%. 
     Example 8 
     In this example, 9 mg amino-graphene quantum dots and 91 mg stannous chloride were dissolved into 1 mL ethanol solution, and 0.123 mg FN—Br and 123 mg spiro-OMeTAD were dissolved into 1 mL chlorobenzene (through calculation, in this example, the amino-graphene had a concentration of 1 wt %, stannous chloride had a concentration of 10 wt, and a mass ratio of the two was 1:10, spiro-OMeTAD had a concentration of 10 wt %, FN—Br had a concentration of 0.01 wt %, and a mass ratio of the two was 1000:1); other steps were the same as those in Example 3. The reverse-scanning photoelectric efficiency of the perovskite multi-functional device obtained in this example was 19.8%, and the forward scanning result was 19.0%, and the luminous efficiency was 1.9%. 
     Comparative Example 1 
     In this example, no FN—Br was added in the preparation of a hole transport layer, and other steps were the same as those in Example 1. The performance result of the obtained device was shown in  FIGS. 5 and 6 ; the reverse-scanning photoelectric efficiency was 17.4%, and the forward scanning result was lower than 15%, and the luminous efficiency was only 0.2%. 
     Comparative Example 2 
     In this example, no graphene quantum dot was added in the preparation of an electron transport layer, and other steps were the same as those in Example 1. The performance result of the obtained device was shown in  FIGS. 5 and 6 ; the reverse-scanning photoelectric efficiency was 20.2%, and the forward scanning result was lower than 19.5%, and the luminous efficiency was only 1.7%. 
     The specific examples above are used to describe the technical solution and beneficial effects of the present invention. It should be understood that the above examples are merely detailed embodiments of the present invention, but are not intended to limit the present invention. Any amendment, equivalent replacement, improvement and the like made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.