A quasi-two-dimensional perovskite film doped with tri(4-morpholinyl)phosphine oxide and its preparation method and application in light-emitting devices

Abstract

The invention discloses a quasi-two-dimensional perovskite film doped with tri(4-morpholinyl)phosphine oxide, a preparation method thereof and an application thereof in a light-emitting device. The film comprises a quasi-two-dimensional perovskite and tri(4-morpholinyl)phosphine oxide; the molecular formula of the quasi-two-dimensional perovskite is L2A n‑1 B n X 3n+1 , wherein L is a positive monovalent organic ammonium ion, A is a monovalent cation, B is a divalent cation in a perovskite material, X is a monovalent anion, and n is a positive integer greater than 1. The present invention eliminates pinhole defects in a quasi-two-dimensional perovskite film by doping an appropriate amount of tri(4-morpholinyl)phosphine oxide into a perovskite precursor, passivates uncoordinated ion defects, adjusts the phase composition of the quasi-two-dimensional perovskite, and obtains a high-quality quasi-two-dimensional perovskite film with a low defect density without pinholes; the luminous efficiency and luminous intensity of the prepared light-emitting device are significantly improved. At the same time, the preparation method of the present invention is simple, repeatable, and low cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of optoelectronic devices, and in particular relates to a quasi-two-dimensional perovskite film doped with tri(4-morpholinyl)phosphine oxide, a preparation method thereof, and an application thereof in a light-emitting device. Background Art

[0002] Metal halide perovskites have the advantages of high quantum yield, high carrier mobility, high luminescent color purity, adjustable luminescent peak, low cost, and solution preparation, and are expected to become the next generation of display technology. However, the lattice of traditional three-dimensional perovskites is easily destroyed under ultraviolet irradiation, high temperature and humid environment, which accelerates the decomposition of perovskites and causes a sharp decline in device performance. Humidity is the main factor affecting device stability. Quasi-two-dimensional perovskite L2A can be formed by inserting large-sized long-chain organic spacer cations LX into the three-dimensional perovskite ABX3 skeleton. n-1 B n X 3n+1 Thanks to its hydrophobic alkylamine content, quasi-two-dimensional perovskites exhibit better humidity stability than three-dimensional perovskites. In addition, quasi-two-dimensional perovskites have larger exciton binding energy and higher photoluminescence efficiency.

[0003] In the process of quasi-two-dimensional perovskite growth, defects such as pinholes and non-coordinating ions will inevitably exist. These defects will become the center of non-radiative recombination, resulting in poor device performance. In the reported device structure, patent CN113823751A "Perovskite light-emitting diode and its preparation method" introduces TOPO into the quasi-two-dimensional perovskite film by the anti-solvent method, passivates the body / surface defects, and significantly improves the efficiency of the corresponding LED device. It can be seen that the introduction of molecules with P=O functional groups is an effective means to improve the performance of perovskite films and light-emitting diodes. However, the commonly used molecules such as TOPO, TPPO, TFPPO, etc. containing P=O functional groups have very low solubility in perovskite precursors, and usually require additional anti-solvent processes or interface modification engineering to introduce, which greatly increases the difficulty of preparation. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the main purpose of the present invention is to provide a method for preparing a perovskite light-emitting diode by doping tri(4-morpholinyl)phosphine oxide into a quasi-two-dimensional perovskite material as a light-emitting layer, which can effectively improve the current efficiency and luminous intensity of the perovskite light-emitting diode.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A quasi-two-dimensional perovskite film doped with tri(4-morpholinyl)phosphine oxide, comprising a quasi-two-dimensional perovskite and tri(4-morpholinyl)phosphine oxide (TMPO); the molecular formula of the quasi-two-dimensional perovskite is L2A n-1 B n X 3n+1 , wherein L is a positive monovalent organic ammonium ion, A is a monovalent cation at the A position in the perovskite material, B is a divalent cation at the B position in the perovskite material, X is a monovalent anion in the perovskite material, X is a monovalent anion in the perovskite material, and n is a positive integer greater than 1.

[0007] Preferably, the monovalent organic ammonium ion is a phenylpropylamine ion (PPA + ), phenethylamine ion (PEA + ), phenylbutylamine ion (PBA + ), isobutylammonium ion (i-BA + )

[0008] Preferably, the monovalent cation at position A is a formamidinium cation (FA + ), methylamine cation (MA + ), Cs + One or more of; the divalent cation at position B is Pb 2+ , Sn 2+ ,Ge 2+ One or more of; X is Cl - ,Br - , I - One or more of .

[0009] Preferably, the thickness of the tri(4-morpholinyl)phosphine oxide-doped quasi-two-dimensional perovskite film is 50-200 nm.

[0010] The present invention provides a method for preparing a quasi-two-dimensional perovskite film doped with tri(4-morpholinyl)phosphine oxide, comprising the following steps:

[0011] Tri(4-morpholinyl)phosphine oxide is added to a quasi-two-dimensional perovskite precursor solution, stirred to obtain a mixed solution, spin-coated to form a film, and annealed to obtain the tri(4-morpholinyl)phosphine oxide-doped quasi-two-dimensional perovskite film.

[0012] Preferably, the perovskite precursor solution is prepared by dissolving LX, AX, and BX2 in a solvent.

[0013] Preferably, the molar ratio of LX, AX and BX2 is LX:AX:BX2=(1-3):(2-3):3.

[0014] Preferably, the total content of LX, AX and BX2 in the perovskite precursor solution is 3-12 wt %.

[0015] Preferably, the solvent is one or more of anhydrous N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO).

[0016] Preferably, in the perovskite precursor solution, the doping concentration of tri(4-morpholinyl)phosphine oxide is 1-8 mg / mL.

[0017] Preferably, the spin coating speed is 2000-7000 rpm, and the spin coating time is 40-80 s.

[0018] Preferably, the annealing is performed under a protective atmosphere, the annealing time is 10-40 minutes, and the annealing temperature is 60-100°C.

[0019] The present invention provides a light-emitting device based on a quasi-two-dimensional perovskite film doped with tri(4-morpholinyl)phosphine oxide, wherein the light-emitting device comprises, from bottom to top, an anode, a hole injection layer, a light-emitting layer, an electron transport layer, an electron injection layer and a cathode; the light-emitting layer is the quasi-two-dimensional perovskite film doped with tri(4-morpholinyl)phosphine oxide prepared by the above method.

[0020] Preferably, the anode is a metal or a metal oxide; further preferably, the metal oxide is one of indium tin oxide conductive film (ITO), fluorine-doped tin oxide (FTO) or indium zinc oxide (IZO).

[0021] Preferably, the hole injection layer is one or more of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) (PEDOT:PSS), poly(9-vinylcarbazole) (PVK), poly[bis(4-phenyl)(4-butylphenyl)amine] (poly-TPD) or poly[(N,N'-(4-n-butylphenyl)-N,N'-diphenyl-1,4-aniline)-alt-(9,9-di-n-octylfluorenyl-2,7-diyl)] (TFB).

[0022] Preferably, the electron transport layer material is any one of 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi), 3,3'-[5'-[3-(3-pyridyl)phenyl][1,1':3',1"-terphenyl]-3,3"-diyl]bipyridine (TmPyPB), and 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline (BCP).

[0023] Preferably, the electron injection layer material is LiF.

[0024] Preferably, the thickness of the electron transport layer is 20-50 nm.

[0025] Preferably, the thickness of the electron injection layer is 0.5-1 nm.

[0026] Preferably, the cathode material is a metal, a metal alloy or a metal oxide.

[0027] Preferably, the thickness of the cathode is 80-150 nm.

[0028] Preferably, the cathode processing method includes vacuum evaporation, magnetron sputtering, solution processing, and inkjet printing.

[0029] The method for preparing the above-mentioned light-emitting device based on tri(4-morpholinyl)phosphine oxide-doped quasi-two-dimensional perovskite film comprises the following steps:

[0030] (1) Cleaning the anode substrate and performing surface treatment;

[0031] (2) preparing a hole injection layer;

[0032] (3) Preparation of perovskite light-emitting layer: using a pipette, dropwise add the prepared tri(4-morpholinyl)phosphine oxide-doped quasi-two-dimensional perovskite precursor solution onto the hole injection layer film, spin-coat and then anneal;

[0033] (4) preparing an electron transport layer: evaporating an electron transport layer material on the perovskite light-emitting layer under high vacuum to obtain an electron transport layer;

[0034] (5) preparing an electron injection layer: thermally evaporating and depositing an electron injection layer on the electron transport layer under high vacuum;

[0035] (6) Preparation of cathode: Vapor deposit a certain thickness of cathode material on the electron injection layer.

[0036] Preferably, the anode substrate in step (1) is one of an ITO substrate, a FTO substrate or an IZO substrate.

[0037] Preferably, the cleaning of the anode substrate in step (1) comprises: sequentially placing the anode substrate in tetrahydrofuran, isopropanol, washing liquid, and deionized water for cleaning, and then placing the anode substrate in isopropanol for ultrasonic cleaning, wherein each ultrasonic cleaning time is 15-30 minutes; the surface treatment comprises: after the above cleaning is completed, placing the substrate in an oven at 70° C. and drying it for more than 4 hours, and then performing UV or O2-Plasma surface treatment on the substrate for 15-20 minutes.

[0038] Preferably, the hole injection layer preparation method in step (2) is as follows: the hole injection layer polymer solution is a PEDOT:PSS (4083) aqueous solution, which is filtered through a 0.22 μm aqueous filter head and then dripped onto the anode substrate to form a hole injection layer film by spin coating, with a spin coating speed of 2000-4000 rpm, a spin coating time of 30-40 s, and annealing at 120-170° C. for 10-20 min in an atmospheric environment. Preferably, the spin coating speed is 3000 rpm, the amount is 45 uL, the spin coating time is 30 s, and the annealing is 150° C. for 15 min.

[0039] Preferably, in step (3), the spin coating speed of the perovskite precursor solution is 2000-7000 rpm, the spin coating time is 40-80 s, and then annealing is performed at 60-100° C. for 10-40 min in a nitrogen environment in a glove box.

[0040] Preferably, steps (4), (5) and (6) all require the device to be introduced into a vacuum evaporation chamber for evaporation of the electron transport layer, the electron injection layer and the cathode. The thickness of the evaporated electron transport layer is 20-50nm; the thickness of the evaporated electron injection layer is 0.5-1nm; the thickness of the evaporated cathode is 80-150nm.

[0041] The present invention adds an appropriate amount of tri(4-morpholinyl)phosphine oxide (TMPO) into the quasi-two-dimensional perovskite precursor. The O atom on the P=O double bond in TMPO can provide a lone pair of electrons to passivate the uncoordinated Pb 2+ ions, reducing the non-radiative recombination of carriers. In addition, the introduction of an appropriate amount of TMPO can also improve the film morphology and eliminate pinhole defects at the grain boundaries, thereby obtaining a film with a dense surface and no pinholes.

[0042] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0043] (1) In the process of preparing the light-emitting layer, the present invention adds an appropriate amount of tri(4-morpholinyl)phosphine oxide to the quasi-two-dimensional perovskite precursor, thereby eliminating the pinhole defects in the quasi-two-dimensional perovskite film, passivating the uncoordinated ion defects, adjusting the phase composition of the quasi-two-dimensional perovskite, and obtaining a dense, pinhole-free, low-defect density, high-quality quasi-two-dimensional perovskite film.

[0044] (2) The current efficiency and luminous intensity of the light-emitting device based on the quasi-two-dimensional perovskite film doped with tri(4-morpholinyl)phosphine oxide prepared by the present invention are significantly improved compared with the light-emitting device of the quasi-two-dimensional perovskite film not doped with tri(4-morpholinyl)phosphine oxide. In some embodiments of the present invention, the current efficiency and luminous brightness of the prepared light-emitting device can reach 25.95 cd / A and 16867 cd / m 2 , which are 2.5 and 2 times higher than the control ratio respectively.

[0045] (3) The process provided by the present invention is simple, has good repeatability and low cost, and provides a new feasible idea for preparing high-efficiency light-emitting diodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 Schematic diagram of the structure of a light-emitting device based on a quasi-two-dimensional perovskite film doped with tri(4-morpholinyl)phosphine oxide;

[0047] Figure 2 This is a scanning electron microscope image of the quasi-two-dimensional perovskite film doped with tri(4-morpholinyl)phosphine oxide prepared in Example 1;

[0048] Figure 3 This is a scanning electron microscope image of a quasi-two-dimensional perovskite film without doping tri(4-morpholinyl)phosphine oxide prepared in Comparative Example 1;

[0049] Figure 4 The voltage-current density-brightness curves of the perovskite light-emitting diodes prepared in Example 1 and Comparative Example 1;

[0050] Figure 5 The current density-current efficiency curves of the perovskite light-emitting diodes prepared in Example 1 and Comparative Example 1;

[0051] Figure 6 The voltage-current density-brightness curves of the perovskite light-emitting diodes prepared in Example 2 and Comparative Example 2;

[0052] Figure 7 The current density-current efficiency curves of the perovskite light-emitting diodes prepared in Example 2 and Comparative Example 2. DETAILED DESCRIPTION

[0053] The present invention is described in detail below in conjunction with the examples. This example provides a detailed implementation method and specific operation process based on the technical solution of the present invention. The protection scope of the present invention includes but is not limited to the following examples.

[0054] Example 1

[0055] In this case, a perovskite light-emitting diode based on a quasi-two-dimensional perovskite film doped with tri(4-morpholinyl)phosphine oxide was prepared. The device structure is: anode (ITO) / hole injection layer (PEDOT:PSS:4083) / quasi-two-dimensional green light perovskite light-emitting layer doped with tri(4-morpholinyl)phosphine oxide (PPA2FA2Pb3Br 10 / TMPO) / electron transport layer (TPBi) / / electron injection layer (LiF) / cathode (Al), such as Figure 1 The specific preparation process is as follows:

[0056] a. Place the ITO substrate in tetrahydrofuran, isopropanol, micron-grade semiconductor cleaning solution (a mixed solution of ZT-3 electronic cleaning solution and deionized water with a volume ratio of 1:100), deionized water, and isopropanol for ultrasonic cleaning in turn. Each ultrasonic cleaning lasts for 30 minutes. After the ultrasonic cleaning is completed, place the ITO substrate in an oven at 70°C and dry it for more than 4 hours for later use;

[0057] b. Prepare a quasi-two-dimensional perovskite precursor solution doped with tri(4-morpholinyl)phosphine oxide: 1) dissolve PPABr, FABr and PbBr2 in DMF at a molar ratio of 2:2.5:3 to obtain a perovskite precursor solution, and the mass fraction of the solute is 6 wt%; 2) weigh a certain amount of tri(4-morpholinyl)phosphine oxide and add it to the perovskite precursor solution, the doping concentration of tri(4-morpholinyl)phosphine oxide in the precursor solution is 4 mg / mL, and stir at room temperature overnight;

[0058] c. Before spin coating the hole injection layer, the ITO substrate was UV treated for 15 minutes to improve the wettability of ITO. The hole injection layer solution (PEDOT:PSS:4083) was then filtered through a 0.22 μm aqueous filter head and dripped onto the ITO substrate. The solution was spin coated at 3000 rpm for 35 seconds and then transferred to a 150°C heating table for annealing at 150°C for 15 minutes.

[0059] d. According to the stacking order of the device structure, the substrate is transferred into the glove box and the quasi-two-dimensional perovskite precursor solution doped with tri(4-morpholinyl)phosphine oxide prepared in step b is spin-coated to prepare the perovskite layer PPA2FA2Pb3Br 10 / TMPO, the spin coating speed is 4000 rpm, the spin coating time is 60s, and then the heat treatment is carried out at a temperature of 85°C for 30min to obtain a perovskite light-emitting layer with a film thickness of 80nm;

[0060] e. After all functional layers are spin-coated, the device is transferred to a vacuum evaporation chamber for evaporation of the electron transport layer, electron injection layer and cathode. The thickness of the evaporated electron transport layer is 40nm, the thickness of the evaporated electron injection layer is 1nm, and the thickness of the evaporated cathode is 100nm;

[0061] f. After the aluminum electrode is evaporated, a perovskite light-emitting diode based on a quasi-two-dimensional perovskite film doped with tri(4-morpholinyl)phosphine oxide is obtained.

[0062] The device was encapsulated with epoxy resin and a glass cover, and the electrical properties (electrical properties such as device current, voltage, brightness, efficiency and color coordinates) were characterized outside the glove box.

[0063] Comparative Example 1

[0064] In this case, a perovskite light-emitting diode based on a quasi-two-dimensional perovskite film without doping tri(4-morpholinyl)phosphine oxide was prepared. The device structure is: anode (ITO) / hole injection layer (PEDOT:PSS:4083) / quasi-two-dimensional green light perovskite light-emitting layer (PPA2FA2Pb3Br 10 ) / electron transport layer (TPBi) / electron injection layer (LiF) / cathode (Al);

[0065] In this case, the preparation steps are basically the same as those in Example 1, except that tri(4-morpholinyl)phosphine oxide is not doped, and the quasi-two-dimensional perovskite material PPA2FA2Pb3Br is directly prepared. 10 As a perovskite light-emitting layer.

[0066] Example 1: Tri(4-morpholinyl)phosphine oxide-doped quasi-two-dimensional perovskite film (PPA2FA2Pb3Br 10 / TMPO) and the quasi-two-dimensional perovskite film (PPA2FA2Pb3Br) prepared in Comparative Example 1 without doping tri(4-morpholinyl)phosphine oxide 10 ) are shown in the scanning electron microscope images. Figure 2 and Figure 3 shown. Figure 3 The quasi-two-dimensional perovskite film has poor morphology and contains a large number of pinholes; Figure 2 After the quasi-two-dimensional perovskite film was doped with tri(4-morpholinyl)phosphine oxide, the pinholes disappeared and a dense, pinhole-free, high-quality film was obtained.

[0067] Quasi-two-dimensional perovskite film (PPA2FA2Pb3Br) based on tri(4-morpholinyl)phosphine oxide doping prepared in Example 1 10 / TMPO) perovskite light-emitting diode and the quasi-two-dimensional perovskite film (PPA2FA2Pb3Br3) based on undoped tri(4-morpholinyl)phosphine oxide prepared in comparative example 1 10 The voltage-current density-brightness curve of the perovskite light-emitting diode is as follows Figure 4 As shown, the brightness of the device in Comparative Example 1 is only 8044 cd / m 2 The brightness of the device in Example 1 is 16867 cd / m 2 , which is more than doubled compared to Comparative Example 1.

[0068] Quasi-two-dimensional perovskite film (PPA2FA2Pb3Br) based on tri(4-morpholinyl)phosphine oxide doping prepared in Example 1 10 / TMPO) perovskite light-emitting diode and the quasi-two-dimensional perovskite film (PPA2FA2Pb3Br3) based on undoped tri(4-morpholinyl)phosphine oxide prepared in comparative example 1 10The current density-current efficiency curve of the perovskite light-emitting diode is as follows Figure 5 As shown, the current efficiency of the device of comparative example 1 is only 10.19 cd / A, while the current efficiency of the device of embodiment 1 is 25.95 cd / A, which is more than 1.5 times higher than that of comparative example 1.

[0069] Example 2

[0070] In this case, a perovskite light-emitting diode based on a quasi-two-dimensional perovskite film doped with tri(4-morpholinyl)phosphine oxide was prepared. The device structure is: anode (ITO) / hole injection layer (PEDOT:PSS:4083) / quasi-two-dimensional green light perovskite light-emitting layer doped with tri(4-morpholinyl)phosphine oxide PEA2Cs2Pb3Br 10 / TMPO) / electron transport layer (TPBi) / electron injection layer (LiF) / cathode (Al).

[0071] The preparation process is as follows:

[0072] a. Place the ITO substrate in tetrahydrofuran, isopropanol, micron-grade semiconductor cleaning solution (a mixed solution of ZT-3 electronic cleaning solution and deionized water with a volume ratio of 1:100), deionized water, and isopropanol for ultrasonic cleaning in turn. Each ultrasonic cleaning lasts for 30 minutes. After the ultrasonic cleaning is completed, place the ITO substrate in an oven at 70°C and dry it for more than 4 hours for later use;

[0073] b. Preparation of a quasi-two-dimensional perovskite precursor solution doped with tri(4-morpholinyl)phosphine oxide: 1) dissolving PEABr, CsBr and PbBr2 in DMSO at a molar ratio of 1.2:3:3 to obtain a perovskite precursor solution, wherein the mass fraction of the solute is 6 wt.%; 2) weighing a certain amount of tri(4-morpholinyl)phosphine oxide, adding it to the perovskite precursor solution, wherein the doping concentration of tri(4-morpholinyl)phosphine oxide in the precursor solution is 3 mg / mL, and stirring at room temperature overnight;

[0074] c. Before spin coating the hole injection layer, the ITO substrate was UV treated for 15 minutes to improve the wettability of ITO. The hole injection layer solution (PEDOT:PSS:4083) was then filtered through a 0.22 μm aqueous filter head and dripped onto the ITO substrate, spin coated at 3000 rpm for 35 seconds, and then transferred to a 150°C heating table for annealing at 150°C for 15 minutes;

[0075] d. According to the stacking order of the device structure, the substrate is transferred into the glove box and the quasi-two-dimensional perovskite precursor solution doped with tri(4-morpholinyl)phosphine oxide prepared in step b is spin-coated to prepare the perovskite layer PEA2Cs2Pb3Br 10 / TMPO, the spin coating speed is 5000 rpm, the spin coating time is 60s, and then the heat treatment is carried out at a temperature of 70°C for 10min to obtain a perovskite light-emitting layer with a film thickness of 50nm;

[0076] e. After all functional layers are spin-coated, the device is transferred to a vacuum evaporation chamber for evaporation of the electron transport layer, electron injection layer and cathode. The thickness of the evaporated electron transport layer is 40nm, the thickness of the evaporated electron injection layer is 1nm, and the thickness of the evaporated cathode is 100nm;

[0077] f. After the aluminum electrode is evaporated, a perovskite light-emitting diode based on a quasi-two-dimensional perovskite film doped with tri(4-morpholinyl)phosphine oxide is obtained.

[0078] The device was encapsulated with epoxy resin and a glass cover, and the electrical properties (electrical properties such as device current, voltage, brightness, efficiency and color coordinates) were characterized outside the glove box.

[0079] Comparative Example 2

[0080] In this case, a perovskite light-emitting diode based on a quasi-two-dimensional perovskite film without doping tri(4-morpholinyl)phosphine oxide was prepared. The device structure is: anode (ITO) / hole injection layer (PEDOT:PSS:4083) / quasi-two-dimensional green light perovskite light-emitting layer (PEA2Cs2Pb3Br 10 ) / electron transport layer (TPBi) / electron injection layer (LiF) / cathode (Al);

[0081] In this comparative example, the preparation steps are the same as those in Example 2, except that tri(4-morpholinyl)phosphine oxide is not doped, and the quasi-two-dimensional perovskite material PEA2Cs2Pb3Br is directly prepared. 10 As a perovskite light-emitting layer.

[0082] Example 2 Preparation of quasi-two-dimensional perovskite film (PEA2Cs2Pb3Br based on tri(4-morpholinyl)phosphine oxide doping) 10 / TMPO) perovskite light-emitting diode and the quasi-two-dimensional perovskite film (PEA2Cs2Pb3Br3) based on undoped tri(4-morpholinyl)phosphine oxide prepared in comparative example 2 10 The voltage-current density-brightness curve of the perovskite light-emitting diode is as follows Figure 6 As shown, the brightness of the device in Comparative Example 2 is only 2516 cd / m 2 The brightness of Example 2 is 14813cd / m 2 , which is more than 4.8 times stronger than Comparative Example 2.

[0083] Example 2 Preparation of quasi-two-dimensional perovskite film (PEA2Cs2Pb3Br based on tri(4-morpholinyl)phosphine oxide doping) 10 / TMPO) perovskite light-emitting diode and the quasi-two-dimensional perovskite film (PEA2Cs2Pb3Br3) based on undoped tri(4-morpholinyl)phosphine oxide prepared in comparative example 2 10 The current density-current efficiency curve of the perovskite light-emitting diode is as follows Figure 7 As shown, the current efficiency of the device of Comparative Example 2 is only 0.639 cd / A, while the current efficiency of the device of Example 2 is 5.19 cd / A, which is more than 7 times higher than that of Comparative Example 2.

[0084] Example 3

[0085] In this case, a perovskite light-emitting diode based on a quasi-two-dimensional perovskite film doped with tri(4-morpholinyl)phosphine oxide was prepared. The device structure is: anode (ITO) / hole injection layer (PEDOT:PSS:4083) / quasi-two-dimensional green light perovskite light-emitting layer doped with tri(4-morpholinyl)phosphine oxide (PPA2FA2Pb3Br 10 / TMPO) / electron transport layer (TPBi) / electron injection layer (LiF) / cathode (Al).

[0086] The preparation steps are basically the same as those in Example 1, except that: in step b, the concentration of the perovskite precursor solution is 12wt%, and the TMPO doping concentration is 8mg / mL; in step d, the spin coating speed is 7000rpm, the time is 80s, and the heat treatment temperature is 60°C, and the time is 40min. The prepared tri(4-morpholinyl)phosphine oxide doped quasi-two-dimensional perovskite light-emitting diode has a current efficiency and a luminous brightness of 19.24cd / A and 10719cd / m 2 The current efficiency and luminous brightness of the device without TMPO are 5.15cd / A and 6319cd / m 2 .

[0087] Example 4

[0088] In this case, a perovskite light-emitting diode based on a quasi-two-dimensional perovskite film doped with tri(4-morpholinyl)phosphine oxide was prepared. The device structure is: anode (ITO) / hole injection layer (PEDOT:PSS:4083) / quasi-two-dimensional green light perovskite light-emitting layer doped with tri(4-morpholinyl)phosphine oxide (PEA2FA2Pb3Br 10 / TMPO) / electron transport layer (TPBi) / electron injection layer (LiF) / cathode (Al).

[0089] The preparation steps are basically the same as those in Example 1, except that: PPABr in step b is replaced by PEABr, the precursor concentration is 3wt%, and the doping concentration of TMPO is 1mg / mL; in step d, the spin coating speed is 2000rpm, the time is 80s, and the heat treatment temperature is 100℃, and the time is 10min. The current efficiency and luminous brightness of the prepared tri(4-morpholinyl)phosphine oxide-doped quasi-two-dimensional perovskite light-emitting diode are 6.16cd / A and 5745cd / m 2 The current efficiency and luminous brightness of the device without TMPO are 3.58cd / A and 4230cd / m 2 .

[0090] Example 5

[0091] In this case, a perovskite light-emitting diode based on a quasi-two-dimensional perovskite film doped with tri(4-morpholinyl)phosphine oxide was prepared. The device structure is: anode (ITO) / hole injection layer (PEDOT:PSS:4083) / quasi-two-dimensional green light perovskite light-emitting layer doped with tri(4-morpholinyl)phosphine oxide (PPA 0.9 i-BA 0.1 )2FA2Pb3Br 10 / TMPO) / electron transport layer (TPBi) / electron injection layer (LiF) / cathode (Al).

[0092] The preparation steps are basically the same as those in Example 1, except that the PPABr in step b is partially replaced by i-BABr, and the molar ratio of PPABr to i-BABr is 0.9:0.1. The current efficiency and luminous brightness of the prepared tri(4-morpholinyl)phosphine oxide-doped quasi-two-dimensional perovskite light-emitting diode are 16.04 cd / A and 8774 cd / m 2 The current efficiency and luminous brightness of the device without TMPO are 5.27cd / A and 6906cd / m 2 .

[0093] Example 6

[0094] In this case, a perovskite light-emitting diode based on a quasi-two-dimensional perovskite film doped with tri(4-morpholinyl)phosphine oxide was prepared. The device structure is anode (ITO) / hole injection layer (PVK) / quasi-two-dimensional green light perovskite light-emitting layer doped with tri(4-morpholinyl)phosphine oxide (PPA2FA2Pb3Br 10 / TMPO) / electron transport layer (TPBi) / electron injection layer (LiF) / cathode (Al).

[0095] The preparation steps are basically the same as those in Example 1, except that the hole injection layer solution PEDOT:PSS:4083 in step c is replaced with a 4 mg / mL PVK chlorobenzene solution, the spin coating speed is 4000 rpm, the spin coating time is 40 s, the annealing temperature is 120°C, and the time is 10 min. The current efficiency and luminous brightness of the prepared tri(4-morpholinyl)phosphine oxide-doped quasi-two-dimensional perovskite light-emitting diode are 16.27 cd / A and 7490 cd / m 2 The current efficiency and luminance of the device without TMPO were 4.73cd / A and 5363cd / m 2 .

[0096] Example 7

[0097] In this case, a perovskite light-emitting diode based on a quasi-two-dimensional perovskite film doped with tri(4-morpholinyl)phosphine oxide was prepared. The device structure is: anode (ITO) / hole injection layer (PEDOT:PSS:4083 / TFB) / quasi-two-dimensional green light perovskite light-emitting layer doped with tri(4-morpholinyl)phosphine oxide (PPA2FA2(Ge 0.1 Pb 0.9 )3Br 10 / TMPO) / electron transport layer (TPBi) / electron injection layer (LiF) / cathode (Al).

[0098] The preparation steps are basically the same as those in Example 1, except that: PbBr2 in step b is partially replaced by GeBr2, and the molar ratio of GeBr2 to PbBr2 is 0.1:0.9. The current efficiency and luminous brightness of the prepared tri(4-morpholinyl)phosphine oxide-doped quasi-two-dimensional perovskite light-emitting diode are 10.16 cd / A and 8207 cd / m 2 The current efficiency and luminous brightness of the device without TMPO are 3.99cd / A and 5159cd / m 2 .

[0099] Example 8

[0100] In this case, a perovskite light-emitting diode based on a quasi-two-dimensional perovskite film doped with tri(4-morpholinyl)phosphine oxide was prepared. The device structure is: anode (ITO) / hole injection layer (PEDOT:PSS:4083 / TFB) / quasi-two-dimensional blue light perovskite light-emitting layer doped with tri(4-morpholinyl)phosphine oxide (PEA2Cs2Pb3(Br / Cl) 10 / TMPO) / electron transport layer (TmPyPB) / electron injection layer (LiF) / cathode (Al).

[0101] The preparation steps are basically the same as those in Example 2, except that: the composition of the perovskite precursor solution in step b is: PEABr:CsBr:PbCl2:PbBr2=3:3:0.9:2.1, the concentration of the precursor solution is 9wt%, and the TMPO doping concentration is 2mg / mL; the evaporated electron transport layer in step e is replaced by TmPyPB with a thickness of 40nm. The current efficiency and luminous brightness of the prepared tri(4-morpholinyl)phosphine oxide-doped quasi-two-dimensional perovskite light-emitting diode are 1.43cd / A and 209 cd / m 2 The current efficiency and luminous brightness of the device without TMPO were 1.09cd / A and 98cd / m 2 .

[0102] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A quasi-two-dimensional perovskite film doped with tri(4-morpholinyl)phosphine oxide, characterized in that: It includes a quasi-two-dimensional perovskite and tri(4-morpholinyl)phosphine oxide; the molecular formula of the quasi-two-dimensional perovskite is L2A n-1 B n X 3n+1 , wherein L is a positive monovalent organic ammonium ion, A is a monovalent cation at the A position in the perovskite material, B is a divalent cation at the B position in the perovskite material, X is a monovalent anion in the perovskite material, and n is a positive integer greater than 1.

2. The quasi-two-dimensional perovskite film doped with tri(4-morpholinyl)phosphine oxide according to claim 1, characterized in that: The monovalent organic ammonium ion is PPA + , PEA + , PBA + , i-BA + One or more of; the monovalent cation at position A is FA + , M.A. + , Cs + One or more of; the divalent cation at position B is Pb 2+ , Sn 2+ ,Ge 2+ One or more of; X is Cl - ,Br - , I - One or more of .

3. The quasi-two-dimensional perovskite film doped with tri(4-morpholinyl)phosphine oxide according to claim 1, characterized in that: The thickness of the tri(4-morpholinyl)phosphine oxide-doped quasi-two-dimensional perovskite film is 50-200 nm.

4. A method for preparing a quasi-two-dimensional perovskite film doped with tri(4-morpholinyl)phosphine oxide according to any one of claims 1 to 3, characterized in that: The following steps are involved: Tri(4-morpholinyl)phosphine oxide is added to a quasi-two-dimensional perovskite precursor solution, wherein the doping concentration of tri(4-morpholinyl)phosphine oxide is 1-8 mg / mL, and the mixed solution is obtained by stirring, and the solution is spin-coated and annealed to obtain the quasi-two-dimensional perovskite film doped with the tri(4-morpholinyl)phosphine oxide.

5. The preparation method according to claim 4, characterized in that: The perovskite precursor solution is prepared by dissolving LX, AX, and BX2 in a solvent, wherein the molar ratio of LX, AX, and BX2 is (1-3):(2-3):3; the total content of LX, AX, and BX2 in the perovskite precursor solution is 3-12wt%; and the solvent is one or more of anhydrous N,N-dimethylformamide and dimethyl sulfoxide.

6. The preparation method according to claim 4, characterized in that: The spin coating speed is 2000-7000 rpm, and the spin coating time is 40-80 s; the annealing is carried out under a protective atmosphere, the annealing time is 10-40 min, and the annealing temperature is 60-100° C.

7. A light-emitting device based on the quasi-two-dimensional perovskite thin film doped with tri(4-morpholinyl)phosphine oxide according to any one of claims 1 to 3, characterized in that: The light-emitting device comprises, from bottom to top, an anode, a hole injection layer, a light-emitting layer, an electron transport layer, an electron injection layer and a cathode; the light-emitting layer is a quasi-two-dimensional perovskite film doped with tri(4-morpholinyl)phosphine oxide.

8. The light emitting device according to claim 7, characterized in that: The anode is a metal or a metal oxide, and the metal oxide is one of ITO, FTO or IZO; the hole injection layer is one or more of PEDOT:PSS, PVK, poly-TPD or TFB; the electron transport layer material is any one of TPBi, TmPyPB, BCP; the electron injection layer material is LiF; the thickness of the electron transport layer is 20-50nm, and the thickness of the electron injection layer is 0.5-1nm.

9. The light emitting device according to claim 7, characterized in that: The cathode is a metal, a metal alloy or a metal oxide; the thickness of the cathode is 80-150 nm; the processing methods of the cathode include vacuum evaporation, magnetron sputtering, solution processing and inkjet printing.

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