Display panel

Abstract

Disclosed in embodiments of the present application is a display panel. A light-emitting element of the display panel comprises a first electrode layer, a first light-emitting layer, a first buffer layer, a first charge generation layer, a second buffer layer, a second light-emitting layer, and a second electrode layer; the first charge generation layer comprises a first n-type charge generation layer and a first p-type charge generation layer; and the electron mobility of the first buffer layer and the electron mobility of the second buffer layer are both less than the electron mobility of the first n-type charge generation layer.

Description

Display panel Technical Field

[0001] The present application relates to the field of display, and in particular to a display panel. Background Art

[0002] Currently, organic light-emitting diodes (OLEDs) are attracting widespread attention in the display field due to their excellent properties, such as thinness, lightweight, high-speed response to input signals, and ability to operate at low DC voltages. In an OLED with multiple first light-emitting units, n-type and p-type charge generation layers are required between the units to provide electrons and holes, respectively. As shown in Figure 1, the direct contact between the two charge generation layers can lead to technical issues such as reverse charge sensitivity, which can cause unstable device operation at high operating temperatures.

[0003] Therefore, a display panel is urgently needed to solve the above technical problems. Technical issues

[0004] The present application provides a display panel that can alleviate the technical problem of unstable device operation caused by direct contact between an n-type charge generation layer and a p-type charge generation layer in an organic light-emitting element having multiple light-emitting units. Technical Solutions

[0005] To solve the above problems, the technical solutions provided by this application are as follows:

[0006] The present application provides a display panel, comprising:

[0007] substrate;

[0008] A first electrode layer is provided on one side of the substrate;

[0009] a first light-emitting layer, disposed on a side of the first electrode layer away from the substrate;

[0010] a first buffer layer, disposed on a side of the first light-emitting layer away from the substrate;

[0011] a first charge generation layer, disposed on a side of the first buffer layer away from the substrate, the first charge generation layer comprising: a first n-type charge generation layer disposed on a side of the first buffer layer away from the substrate, and a first p-type charge generation layer disposed on a side of the first n-type charge generation layer away from the substrate;

[0012] a second buffer layer disposed between the first n-type charge generation layer and the first p-type charge generation layer;

[0013] a second light-emitting layer, disposed on a side of the first charge generation layer away from the substrate;

[0014] a second electrode layer, disposed on a side of the second light-emitting layer away from the substrate;

[0015] wherein the electron mobility of the first buffer layer is smaller than the electron mobility of the first n-type charge generation layer, and the electron mobility of the second buffer layer is smaller than the electron mobility of the first n-type charge generation layer;

[0016] The difference between the highest occupied molecular orbital energy level of the first buffer layer and the lowest unoccupied molecular orbital energy level of the first n-type charge generation layer is greater than 2 eV, and the difference between the highest occupied molecular orbital energy level of the first buffer layer and the lowest unoccupied molecular orbital energy level of the first n-type charge generation layer is less than 4 eV;

[0017] The difference between the highest occupied molecular orbital energy level of the second buffer layer and the lowest unoccupied molecular orbital energy level of the first n-type charge generation layer is greater than 2 eV, and the difference between the highest occupied molecular orbital energy level of the second buffer layer and the lowest unoccupied molecular orbital energy level of the first n-type charge generation layer is less than 4 eV.

[0018] Preferably, the display panel further comprises a first electron transport layer located between the first light-emitting layer and the first buffer layer, wherein a side of the first buffer layer close to the first n-type charge generation layer is in direct contact with the first n-type charge generation layer, and a side of the first buffer layer away from the first n-type charge generation layer is in direct contact with the first electron transport layer;

[0019] A side of the second buffer layer close to the first n-type charge generation layer is in direct contact with the first n-type charge generation layer, and a side of the second buffer layer away from the first n-type charge generation layer is in direct contact with the first p-type charge generation layer.

[0020] Preferably, the difference between the highest occupied molecular orbital energy level of the first buffer layer and the lowest unoccupied molecular orbital energy level of the first electron transport layer is greater than 2eV, and the difference between the highest occupied molecular orbital energy level of the first buffer layer and the lowest unoccupied molecular orbital energy level of the first electron transport layer is less than 4eV.

[0021] Preferably, the electron mobility of the first n-type charge generation layer is greater than or equal to 10 -3 cm 2 / Vs, the electron mobility of the first buffer layer is less than 10 -3 cm 2 / Vs, the electron mobility of the second buffer layer is less than 10 -3 cm 2 / Vs.

[0022] Preferably, the electron mobility of the first electron transport layer is greater than 10-5 cm 2 / Vs, the electron mobility of the first electron transport layer is less than 10 -3 cm 2 / Vs, the electron mobility of the first buffer layer is greater than 10 -5 cm 2 / Vs, the electron mobility of the second buffer layer is greater than 10 -5 cm 2 / Vs.

[0023] Preferably, the electron work function of the first buffer layer is between the electron work function of the first n-type charge generation layer and the electron work function of the first p-type charge generation layer, and the electron work function of the second buffer layer is between the electron work function of the first n-type charge generation layer and the electron work function of the first p-type charge generation layer.

[0024] Preferably, the electron work function of the first buffer layer is greater than 5.5 eV, and the electron work function of the first buffer layer is less than 7.5 eV;

[0025] The electron work function of the second buffer layer is greater than 5.5 eV, and the electron work function of the second buffer layer is less than 7.5 eV.

[0026] Preferably, the first n-type charge generation layer includes a first electron transport material and a first charge doping material, the first buffer layer is composed of the first electron transport material, and the second buffer layer is composed of the first electron transport material.

[0027] Preferably, the difference in thickness between the first buffer layer and the second buffer layer is greater than or equal to 0 angstrom, and the difference in thickness between the first buffer layer and the second buffer layer is less than or equal to 50 angstroms.

[0028] Preferably, in the first n-type charge generation layer, the mass ratio of the first electron transport material to the first charge doping material is 99:1 to 80:20.

[0029] Preferably, the display panel further includes a third buffer layer and a fourth buffer layer, the third buffer layer is located between the first p-type charge generation layer and the second light-emitting layer, and the fourth buffer layer is located between the first p-type charge generation layer and the second buffer layer;

[0030] The hole mobility of the third buffer layer is smaller than that of the first p-type charge generation layer, and the hole mobility of the fourth buffer layer is smaller than that of the first p-type charge generation layer.

[0031] Preferably, the difference between the lowest unoccupied molecular orbital energy level of the third buffer layer and the highest occupied molecular orbital energy level of the first p-type charge generation layer is greater than 2 eV, and the difference between the lowest unoccupied molecular orbital energy level of the third buffer layer and the highest occupied molecular orbital energy level of the first p-type charge generation layer is less than 4 eV;

[0032] The difference between the lowest unoccupied molecular orbital energy level of the fourth buffer layer and the highest occupied molecular orbital energy level of the first p-type charge generation layer is greater than 2eV, and the difference between the lowest unoccupied molecular orbital energy level of the fourth buffer layer and the highest occupied molecular orbital energy level of the first p-type charge generation layer is less than 4eV.

[0033] Preferably, the display panel further comprises a second hole transport layer located between the second light-emitting layer and the third buffer layer, wherein a side of the third buffer layer close to the first p-type charge generation layer is in direct contact with the first p-type charge generation layer, and a side of the third buffer layer away from the first p-type charge generation layer is in direct contact with the second hole transport layer;

[0034] A side of the fourth buffer layer close to the second buffer layer is in direct contact with the second buffer layer, and a side of the fourth buffer layer away from the second buffer layer is in direct contact with the first p-type charge generation layer.

[0035] Preferably, the difference between the lowest unoccupied molecular orbital energy level of the third buffer layer and the highest occupied molecular orbital energy level of the second hole transport layer is greater than 2eV, and the difference between the lowest unoccupied molecular orbital energy level of the third buffer layer and the highest occupied molecular orbital energy level of the second hole transport layer is less than 4eV.

[0036] Preferably, the hole mobility of the first p-type charge generation layer is greater than or equal to 10 -2 cm 2 / Vs, the hole mobility of the third buffer layer is less than 10 -2 cm 2 / Vs, the hole mobility of the fourth buffer layer is less than 10 -2 cm 2 / Vs.

[0037] Preferably, the hole mobility of the second hole transport layer is greater than 10 -4 cm 2 / Vs, the hole mobility of the third buffer layer is greater than 10 -4 cm 2 / Vs, the hole mobility of the fourth buffer layer is greater than 10 -4 cm 2 / Vs.

[0038] Preferably, the electron work function of the third buffer layer is between the electron work function of the first n-type charge generation layer and the electron work function of the first p-type charge generation layer, and the electron work function of the fourth buffer layer is between the electron work function of the first n-type charge generation layer and the electron work function of the first p-type charge generation layer.

[0039] Preferably, the electron work function of the third buffer layer is greater than 5.5 eV, and the electron work function of the third buffer layer is less than 7.5 eV;

[0040] The electron work function of the fourth buffer layer is greater than 5.5 eV, and the electron work function of the fourth buffer layer is less than 7.5 eV.

[0041] Preferably, the first p-type charge generation layer includes a first hole transport material and a second charge doping material, the third buffer layer is composed of the first hole transport material, and the fourth buffer layer is composed of the first hole transport material.

[0042] Preferably, the difference in thickness between the third buffer layer and the fourth buffer layer is greater than or equal to 0 angstrom, and the difference in thickness between the third buffer layer and the fourth buffer layer is less than or equal to 50 angstroms. Beneficial effects

[0043] The present application provides a first buffer layer and a second buffer layer on opposite sides of a first n-type charge generation layer. The electron mobility of the first buffer layer and the second buffer layer is lower than that of the first n-type charge generation layer. This improves the reverse charge sensitivity generated by direct contact between the first n-type charge generation layer and the first p-type charge generation layer, and acts as a hole blocking layer between the first n-type charge generation layer and the first light-emitting layer, thereby improving the operating stability of the display panel at high temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] FIG1 is a schematic structural diagram of a charge generation layer of a light-emitting element in the prior art;

[0045] FIG2 is a schematic structural diagram of a first structure of a light-emitting element of a display panel provided in an embodiment of the present application;

[0046] 3 is a schematic structural diagram of a structure of a charge generation layer, a first buffer layer, and a second buffer layer of a light-emitting element of a display panel provided in an embodiment of the present application;

[0047] FIG4 is a schematic structural diagram of a second structure of a light-emitting element of a display panel provided in an embodiment of the present application;

[0048] 5 is a schematic structural diagram of a structure of a charge generation layer and a first buffer layer, a second buffer layer, a third buffer layer, and a fourth buffer layer of a light-emitting element of a display panel provided in an embodiment of the present application;

[0049] FIG6 is a schematic structural diagram of a display panel provided in an embodiment of the present application.

[0050] Implementation Methods of the Application

[0051] The present application provides a display panel. To make the purpose, technical solution, and effects of the present application clearer and more explicit, the present application is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and are not intended to limit the present application.

[0052] Currently, in organic light-emitting elements with multiple light-emitting layers, the n-type charge generation sublayer and the p-type charge generation sublayer are in direct contact. When the operating temperature of the light-emitting element is high, there is a technical problem of unstable operation of the light-emitting element due to reverse charge sensitivity.

[0053] Referring to FIG. 2 to FIG. 6 , an embodiment of the present application provides a display panel 10 , including:

[0054] substrate 101;

[0055] A first electrode layer 102 is provided on one side of the substrate 101;

[0056] A first light-emitting layer 103 is provided on a side of the first electrode layer 102 away from the substrate 101;

[0057] A first buffer layer 104 is provided on a side of the first light-emitting layer 103 away from the substrate 101;

[0058] A first charge generation layer 105 is disposed on a side of the first buffer layer 104 away from the substrate 101. The first charge generation layer 105 includes: a first n-type charge generation layer 105a disposed on a side of the first buffer layer 104 away from the substrate 101; and a first p-type charge generation layer 105b disposed on a side of the first n-type charge generation layer 105a away from the substrate 101.

[0059] a second buffer layer 106 disposed between the first n-type charge generation layer 105 a and the first p-type charge generation layer 105 b ;

[0060] A second light-emitting layer 107 is provided on a side of the first charge generation layer 105 away from the substrate 101;

[0061] A second electrode layer 108 is provided on a side of the second light-emitting layer 107 away from the substrate 101;

[0062] The electron mobility of the first buffer layer 104 is smaller than that of the first n-type charge generation layer 105 a , and the electron mobility of the second buffer layer 106 is smaller than that of the first n-type charge generation layer 105 a .

[0063] The difference between the highest occupied molecular orbital energy level of the first buffer layer 104 and the lowest unoccupied molecular orbital energy level of the first n-type charge generation layer 105 a is greater than 2 eV, and the difference between the highest occupied molecular orbital energy level of the first buffer layer 104 and the lowest unoccupied molecular orbital energy level of the first n-type charge generation layer 105 a is less than 4 eV;

[0064] The difference between the highest occupied molecular orbital energy level of the second buffer layer 106 and the lowest unoccupied molecular orbital energy level of the first n-type charge generation layer 105a is greater than 2 eV, and the difference between the highest occupied molecular orbital energy level of the second buffer layer 106 and the lowest unoccupied molecular orbital energy level of the first n-type charge generation layer 105a is less than 4 eV.

[0065] In the embodiment of the present application, a first buffer layer 104 and a second buffer layer 106 are provided on opposite sides of the first n-type charge generation layer 105a. The electron mobility of the first buffer layer 104 and the second buffer layer 106 is lower than that of the first n-type charge generation layer 105a. This improves the reverse charge sensitivity generated by the direct contact between the first n-type charge generation layer 105a and the first p-type charge generation layer 105b, and plays a role in blocking holes between the first n-type charge generation layer 105a and the first light-emitting layer 103, thereby improving the operating stability of the display panel 10 at high temperatures.

[0066] The technical solution of this application is now described in conjunction with specific embodiments.

[0067] Please refer to Figures 2 to 6. In this embodiment, the light-emitting element 100 of the display panel 10 can be composed of a cathode, an anode, at least two adjacent light-emitting units, a charge generation layer, and a buffer layer. The two adjacent light-emitting units are a first light-emitting unit 109 and a second light-emitting unit 110. The first light-emitting unit 109 includes the first light-emitting layer 103, and the second light-emitting unit 110 includes the second light-emitting layer 107. The charge generation layer is located between the adjacent light-emitting units, and the charge generation layer includes the first charge generation layer 105. The buffer layer is located between the adjacent light-emitting units, and the buffer layer includes the first buffer layer 104 and the second buffer layer 106.

[0068] The first electrode layer 102 includes a first electrode layer 102 , and the second electrode layer 108 includes a second electrode layer 108 . The first electrode layer 102 may be an anode, and the second electrode layer 108 may be a cathode.

[0069] The material of the anode is preferably at least one of a metal, an alloy, and a conductive compound. Specifically, it can be a metal oxide such as indium tin oxide, indium zinc oxide, indium zinc tungsten oxide, indium tin zinc, or zinc oxide, or it can be graphene, gold, platinum, nickel, tungsten, chromium, molybdenum, or a nitride of a metal material.

[0070] The material of the cathode is preferably a material having a work function lower than the work function of the anode. The cathode is preferably at least one of a metal, an alloy, and a conductive compound. Specifically, the material of the cathode may include alkali metal elements, alkaline earth metal elements, and rare earth metal elements, such as Ag, Mg, Cu, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, LiF / Ca, LiF / Al, Mo, Ti, Yb, W, or magnesium-silver alloy, aluminum-lithium alloy, etc.; alternatively, the material of the second electrode layer 108 may also be selected from indium tin oxide, indium zinc oxide, zinc oxide, indium tin zinc oxide, etc., and a combination of the aforementioned optional materials for the cathode.

[0071] Referring to Figures 2 to 5 , in this embodiment, the number of light-emitting units located between the first electrode layer 102 and the second electrode layer 108 can be greater than or equal to two. That is, the light-emitting units can include a first light-emitting unit 109, a second light-emitting unit 110, and so on, to an Nth light-emitting unit, where N is an integer greater than or equal to 3. For example, the number of light-emitting units can be two or three, etc. The charge generation layer is located at least between two adjacent light-emitting units. Preferably, when there are more than two light-emitting units located between the first electrode layer 102 and the second electrode layer 108, the charge generation layer is located between every two adjacent light-emitting units, for example, the first charge generation layer 105 located between the first light-emitting unit 109 and the second light-emitting unit 110. The buffer layer is located at least between two adjacent light-emitting units, for example, the first buffer layer 104 located between the first light-emitting unit 109 and the first n-type charge generation layer 105a, and the second buffer layer 106 located between the first n-type charge generation layer 105a and the first p-type charge generation layer 105b.

[0072] Each of the light-emitting units is composed of a hole transport layer, a light-emitting layer, and an electron transport layer stacked in sequence. When the first electrode layer 102 is an anode and the second electrode layer 108 is a cathode, along the direction from the first electrode layer 102 to the second electrode layer 108, each of the light-emitting units is composed of a hole transport layer, a light-emitting layer, and an electron transport layer stacked in sequence. For example, the first light-emitting unit 109 is composed of a first hole transport layer 111, a first light-emitting layer 103, and a first electron transport layer 112 stacked in sequence; the second light-emitting unit 110 is composed of a second hole transport layer 113, a second light-emitting layer 107, and a second electron transport layer 114 stacked in sequence.

[0073] The hole-transporting layer may include a hole-transporting sublayer, for example, the first hole-transporting layer 111 includes a first hole-transporting sublayer, and the second hole-transporting layer 113 includes a second hole-transporting sublayer. Alternatively, the hole-transporting layer may further include a hole-injection sublayer, for example, the first hole-transporting layer 111 includes a first hole-injection sublayer, and the second hole-transporting layer 113 includes a second hole-injection sublayer. Alternatively, the hole-transporting layer may further include an electron-blocking sublayer, for example, the first hole-transporting layer 111 includes a first hole-electron blocking sublayer, and the second hole-transporting layer 113 includes a second electron-blocking sublayer. The hole injection sublayer may include a hole injection material, which may be selected from metal oxides such as molybdenum oxide, titanium oxide, tungsten oxide, silver oxide, etc.; phthalocyanine compounds such as copper phthalocyanine, etc.; such as: carbazole derivatives such as N-phenylcarbazole and polyvinylcarbazole, fluorene derivatives, triphenylamine derivatives such as N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1-biphenyl]-4,4'-diamine (TPD) and 4,4',4"-tri(N-carbazolyl)triphenylamine (TCTA), N,N'-di(naphthalene-1-yl)-N,N'-diphenylbenzidine (NPB), 4,4'-cyclohexylenebis[N,N-diphenyl]-1,1-biphenyl]-4,4'-diamine (TPD), ... (4-methylphenyl) aniline] (TAPC), 4,4'-bis[N,N'-(3-methylphenyl)amino]-3,3'-dimethylbiphenyl (HMTPD), 9-(4-tert-butylphenyl)-3,6-bis(triphenylsilyl)-9H-carbazole (CzSi), 9-phenyl-9H-3,9'-bicarbazole (CCP), 1,3-bis(N-carbazolyl)benzene (mCP), 1,3-bis(1,8-dimethyl-9H-carbazol-9-yl)benzene (mDCP), etc. or a combination thereof. The electron blocking sublayer includes an electron blocking material, which can be selected from aromatic amine compounds, such as triarylamine compounds.

[0074] The electron transport layer may include an electron transport sublayer, for example, the first electron transport layer 112 includes a first electron transport sublayer, and the second electron transport layer 114 includes a second electron transport sublayer. Alternatively, the electron transport layer also includes an electron injection sublayer, for example, the first electron transport layer 112 includes a first electron injection sublayer, and the second electron transport layer 114 includes a second electron injection sublayer. Alternatively, the electron transport layer also includes a hole blocking sublayer, for example, the first electron transport layer 112 includes a first hole blocking sublayer, and the second electron transport layer 114 includes a second hole blocking sublayer. The electron injection sublayer includes an electron injection material, which can be selected from alkali metals, alkaline earth metals, rare earth metals or alkali metal compounds, alkaline earth metal compounds, rare earth metal compounds, etc., such as lithium, lithium fluoride, lithium oxide, calcium fluoride, ytterbium, Liq, KI, NaCl, CsF, Li2O, BaO, etc. The work function of the electron injection sublayer is lower than the work function of the cathode, which facilitates the injection of electrons into the electron transport sublayer. The material of the hole blocking sublayer may include heteroaromatic compounds, such as triazinopyrimidine derivatives, and the like.

[0075] Referring to Figures 2 to 5, in some embodiments, among all the light-emitting units located between the first electrode layer 102 and the second electrode layer 108, the hole-transporting layer of the unit closest to the anode is composed of a hole-injection sublayer, a hole-transporting sublayer, and an electron-blocking sublayer stacked in sequence, with the hole-injection sublayer located on the side of the hole-transporting sublayer close to the anode, and the electron-blocking sublayer located between the hole-transporting sublayer and the light-emitting layer. Among all the light-emitting units located between the first electrode layer 102 and the second electrode layer 108, except for the unit closest to the anode, the hole-transporting layer of the light-emitting units is composed of a hole-transporting sublayer and an electron-blocking sublayer stacked in sequence, with the electron-blocking sublayer located between the hole-transporting sublayer and the light-emitting layer.

[0076] In some embodiments, among all the light-emitting units located between the first electrode layer 102 and the second electrode layer 108, the electron-transporting layer of the unit closest to the cathode comprises an electron injection sublayer, an electron transport sublayer, and a hole blocking sublayer stacked in sequence, the electron injection sublayer being located on the side of the electron transport sublayer 1 close to the cathode, and the hole blocking sublayer being located between the electron transport sublayer and the light-emitting layer. Among all the light-emitting units located between the first electrode layer 102 and the second electrode layer 108, except for the unit closest to the cathode, the electron-transporting layer of the light-emitting units comprises an electron transport sublayer and a hole blocking sublayer stacked in sequence, and the hole blocking sublayer being located between the electron transport sublayer and the light-emitting layer.

[0077] The luminescent colors of the luminescent layers in at least two adjacent luminescent units may be the same or different.

[0078] The light-emitting layer includes a host material. In some embodiments, the host material can be selected from compounds represented by general formula (1):

[0079] [Ar 101 ] m3 [(L 101 ) x3 -R 11x11 ][(L 102 ) y3 -R 12 y 11 ][(L 103 )z3-R 13 z 11 ]

[0080] Among them, Ar 101 may be a substituted or unsubstituted carbocyclic group having 5 to 60 carbon atoms or a substituted or unsubstituted heterocyclic group having 1 to 60 carbon atoms,

[0081] m3 can be selected from 1, 2 or 3,

[0082] L 101 、L 102 、L 103 and each independently selected from a substituted or unsubstituted cycloalkylene group having 3 to 10 carbon atoms, a substituted or unsubstituted heterocycloalkylene group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkenylene group having 3 to 10 carbon atoms, a substituted or unsubstituted heterocycloalkenylene group having 1 to 10 carbon atoms, a substituted or unsubstituted arylene group having 6 to 60 carbon atoms, a substituted or unsubstituted heteroarylene group having 1 to 60 carbon atoms, a substituted or unsubstituted divalent non-aromatic fused polycyclic group, and a substituted or unsubstituted divalent non-aromatic fused heteropolycyclic group.

[0083] x3, y3, z3 can be independently selected from integers from 0 to 5,

[0084] R 11 、R 12 、R 13and -I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazine group, a hydrazone group, a substituted or unsubstituted alkyl group having 1 to 60 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 60 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 60 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 60 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted heterocycloalkane group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkenyl group having 3 to 10 carbon atoms, a substituted or unsubstituted heterocycloalkenyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 60 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 60 carbon atoms, a substituted or unsubstituted arylthio group having 6 to 60 carbon atoms, a substituted or unsubstituted heteroaryl group having 1 to 60 carbon atoms, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, -Si(Q 101 )(Q 102 )(Q 103 )、-N(Q 101 )(Q 102 )、-B(Q 101 )(Q 102 ),-C(=O)(Q 101 )、-S(=O)2(Q 101 ) and -P(=O)(Q 101 )(Q 102 ),

[0085] x11, y11, z11 can be selected from integers from 0 to 5,

[0086] where Q 101 To Q 103 Each may be independently selected from an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, and the like.

[0087] In some embodiments, L 101 、L 102 、L 103 Can be independently selected from one of general formulae (1-1) to (1-3):

[0088] Among them, X 101 To X 101 are independently selected from C, O, S or N-[(L 104 ) xb1 -R 107],

[0089] R 101 to R 106 The alkyl radicals may be independently selected from hydrogen, deuterium, -F, -Cl, -Br, -I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazine group, a hydrazone group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, -Si(Q) 101 )(Q 102 )(Q 103 )、-N(Q 101 )(Q 102 )、-B(Q 101 )(Q 102 ),-C(=O)(Q 101 )、-S(=O)2(Q 101 ) and -P(=O)(Q 101 )(Q 102 ),

[0090] L 104 The selection range is similar to L 101 、L 102 、L 103 The selection range is the same as R 107 The selection range is similar to R 101 、R 102 、R 103 The selection range is the same as

[0091] xb1 is an integer selected from 0 to 2.

[0092] In some embodiments, the host material is selected from the following compounds:

[0093] In some embodiments, the host material may be selected from the following compounds:

[0094] In some embodiments, the light-emitting layer further includes a doping material, and the doping material can be selected from an organic metal complex having a structure represented by general formula (2-1):

[0095] M m2 (L 201 ) x2 (L 202 ) y2 (L 203 ) z2

[0096] wherein M may be selected from iridium (Ir), platinum (Pt), palladium (Pd), osmium (Os), titanium (Ti), zirconium (Zr), hafnium (Hf), europium (Eu), terbium (Tb), rhodium (Rh) and thulium (Tm),

[0097] L 201 、L 202 、L 203 can be independently selected from the ligands shown in formulae (201) to (206):

[0098] Among them, “*” represents the coordination site,

[0099] x2, y2, and z2 are each independently selected from an integer between 0 and 3.

[0100] In some embodiments, the doping material is selected from the following compounds:

[0101] In some embodiments, the doping material is selected from compounds represented by the general formula (2-2):

[0102] Among them, R 201 to R 210 Each of the following groups is independently selected from hydrogen, deuterium, -F, -Cl, -Br, -I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazine group, a hydrazone group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted aromatic amine group having 6 to 60 carbon atoms, and a substituted or unsubstituted heteroaromatic amine group having 5 to 60 carbon atoms.

[0103] In some embodiments, the doping material is selected from the following compounds:

[0104] In some embodiments, the doping material is selected from compounds having a structure represented by general formula (2-3):

[0105] Among them, R 111 to R 121and each is independently selected from hydrogen, deuterium, -F, -Cl, -Br, -I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazine group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted heterocycloalkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkenyl group having 3 to 10 carbon atoms, a substituted or unsubstituted heterocycloalkenyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 60 carbon atoms, a substituted or unsubstituted heteroaryl group having 5 to 60 carbon atoms, a substituted or unsubstituted divalent non-aromatic fused polycyclic group, and a substituted or unsubstituted divalent non-aromatic fused heteropolycyclic group.

[0106] In some embodiments, the doping material is selected from the following compounds:

[0107] In some embodiments, the doping material may also be selected from the following compounds:

[0108] Referring to Figures 2 to 5, in some embodiments, a side of the first buffer layer 104 close to the first n-type charge generation layer 105a is in direct contact with the first n-type charge generation layer 105a, and a side of the first buffer layer 104 away from the first n-type charge generation layer 105a is in direct contact with the first electron transport layer 112.

[0109] The side of the second buffer layer 106 close to the first n-type charge generation layer 105a is in direct contact with the first n-type charge generation layer 105a, and the side of the second buffer layer 106 away from the first n-type charge generation layer 105a is in direct contact with the first p-type charge generation layer 105b.

[0110] The first buffer layer 104 includes one first buffer sublayer, or the first buffer layer 104 includes multiple first buffer sublayers. When the first buffer layer 104 includes one first buffer sublayer, a side of the first buffer layer 104 close to the first n-type charge generation layer 105a is in direct contact with the first n-type charge generation layer 105a, and a side of the first buffer sublayer away from the first n-type charge generation layer 105a is in direct contact with the first electron transport layer 112.

[0111] In some embodiments, the second buffer layer 106 includes one second buffer sublayer, or the second buffer layer 106 includes multiple second buffer sublayers. When the second buffer layer 106 includes one second buffer sublayer, a side of the second buffer sublayer closest to the first n-type charge generation layer 105a is in direct contact with the first n-type charge generation layer 105a. When the second buffer layer 106 includes multiple second buffer sublayers, a side of the second buffer sublayer closest to the first n-type charge generation layer 105a is in direct contact with the first n-type charge generation layer 105a.

[0112] In some embodiments, only the second buffer layer 106 is included between the first n-type charge generation layer 105a and the first p-type charge generation layer 105b, and at least one side of the second buffer layer 106 closest to the first p-type charge generation layer 105b is in direct contact with the first p-type charge generation layer 105b. When the second buffer layer 106 is a single layer, along the direction from the first electrode layer 102 to the second electrode layer 108, opposite sides of the second buffer layer 106 are in direct contact with the first n-type charge generation layer 105a and the first p-type charge generation layer 105b, respectively. When the second buffer layer 106 is multi-layer, along the direction from the first electrode layer 102 to the second electrode layer 108, the side of the second buffer sublayer closest to the first n-type charge generation layer 105a close to the first n-type charge generation layer 105a is in direct contact with the first n-type charge generation layer 105a, and the side of the second buffer sublayer closest to the first p-type charge generation layer 105b close to the first p-type charge generation layer 105b is in direct contact with the first p-type charge generation layer 105b.

[0113] Referring to FIG. 4 and FIG. 5 , in some embodiments, the display panel 10 further includes a third buffer layer 115 . The third buffer layer 115 is located between the first p-type charge generation layer 105 b and the second light emitting layer 107 .

[0114] The hole mobility of the third buffer layer 115 is smaller than the hole mobility of the first p-type charge generation layer 105 b .

[0115] The difference between the lowest unoccupied molecular orbital energy level of the third buffer layer 115 and the highest occupied molecular orbital energy level of the first p-type charge generation layer 105b is greater than 2eV, and the difference between the lowest unoccupied molecular orbital energy level of the third buffer layer 115 and the highest occupied molecular orbital energy level of the first p-type charge generation layer 105b is less than 4eV.

[0116] In some embodiments, the display panel 10 further includes a fourth buffer layer 116 , and the fourth buffer layer 116 is located between the first p-type charge generation layer 105 b and the second buffer layer 106 .

[0117] The hole mobility of the fourth buffer layer 116 is lower than the hole mobility of the first p-type charge generation layer 105 b .

[0118] The difference between the lowest unoccupied molecular orbital energy level of the fourth buffer layer 116 and the highest occupied molecular orbital energy level of the first p-type charge generation layer 105b is greater than 2eV, and the difference between the lowest unoccupied molecular orbital energy level of the fourth buffer layer 116 and the highest occupied molecular orbital energy level of the first p-type charge generation layer 105b is less than 4eV.

[0119] In some embodiments, the side of the third buffer layer 115 close to the first p-type charge generation layer 105 b is in direct contact with the first p-type charge generation layer 105 b , and the side of the third buffer layer 115 away from the first p-type charge generation layer 105 b is in direct contact with the second hole transport layer 113 .

[0120] In some embodiments, a side of the fourth buffer layer 116 close to the second buffer layer 106 is in direct contact with the second buffer layer 106 , and a side of the fourth buffer layer 116 away from the second buffer layer 106 is in direct contact with the first p-type charge generation layer 105 b .

[0121] In some embodiments, the third buffer layer 115 may be one or more. When the third buffer layer 115 has one third buffer sublayer, the side of the third buffer sublayer closest to the first p-type charge generation layer 105b is in direct contact with the first p-type charge generation layer 105b, and the side of the third buffer sublayer away from the first p-type charge generation layer 105b is in direct contact with the second hole transport layer 113. When the third buffer layer 115 has multiple third buffer sublayers, the multiple third buffer sublayers are stacked in sequence, and the side of the third buffer sublayer closest to the first p-type charge generation layer 105b that is closest to the first p-type charge generation layer 105b is in direct contact with the first p-type charge generation layer 105b, and the side of the third buffer sublayer closest to the second hole transport layer 113 is in direct contact with the hole transport layer.

[0122] In some embodiments, the fourth buffer layer 116 may be one or more. When the fourth buffer layer 116 has one fourth buffer sublayer, the side of the fourth buffer sublayer closer to the first n-type charge generation layer 105a is in direct contact with the second buffer layer 106, and the side of the fourth buffer layer 116 farther from the second buffer layer 106 is in direct contact with the first p-type charge generation layer 105b. When the fourth buffer layer 116 has multiple fourth buffer sublayers, the multiple fourth buffer sublayers are stacked sequentially, and the side of the fourth buffer sublayer closest to the second buffer layer 106, which is closer to the second buffer layer 106, is in direct contact with the second buffer layer 106, and the side of the fourth buffer sublayer closest to the first p-type charge generation layer 105b, which is closer to the first p-type charge generation layer 105b, is in direct contact with the first p-type charge generation layer 105b.

[0123] In some embodiments, the first n-type charge generation layer 105 a includes a first electron transport material, and the first buffer layer 104 includes a second electron transport material.

[0124] The first electron transporting material and the second electron transporting material are at least one selected from the group consisting of pyridine derivatives, pyrimidine derivatives, triazine derivatives, imidazole derivatives, oxazole derivatives, and phenanthroline derivatives.

[0125] In some embodiments, the first electron transporting material and the second electron transporting material are independently selected from compounds having the general formula (3):

[0126] Among them, X 301 To X 309 Each of them is independently selected from C, N, a pyridyl group or a group having a pyridine derivative, a pyrimidinyl group or a group having a pyrimidine derivative, a triazine group or a group having a triazine derivative, an imidazolyl group or a group having an imidazole derivative, an oxazolyl group or a group having an oxazole derivative, a phenanthroline group or a group having a phenanthroline derivative.

[0127] In some embodiments, the first electron transporting material and the second electron transporting material are independently selected from the following compounds:

[0128] In some embodiments, the first buffer layer 104 is composed of the second electron transport material, and the second electron transport material is the same as the first electron transport material.

[0129] In some embodiments, the second buffer layer 106 is composed of the second electron transport material.

[0130] In some embodiments, the first buffer layer 104 and the second buffer layer 106 are made of the same material, and are both the same as the first electron transport material.

[0131] In some embodiments, the first n-type charge generation layer 105a further includes a first charge doping material. The first n-type charge generation layer 105a may be composed of the first electron transport material and the first charge doping material.

[0132] The first charge-doping material is selected from at least one of an alkali metal, an alkali metal alloy, an alkaline earth metal, an alkaline earth metal alloy, a lanthanide metal, and a lanthanide metal alloy. The addition of the first charge-doping material helps to improve the electron mobility of the first n-type charge generation layer 105a. Preferably, the mass ratio of the first electron transport material to the first charge-doping material is 99:1 to 80:20, for example, 98:2, 95:5, 92:8, 90:10, 88:12, 85:15, 82:18, etc.

[0133] The material selection range of the electron transport sublayer in the light emitting unit may be the same as or different from the selection range of the first electron transport material and the second electron transport material.

[0134] In some embodiments, the material of the electron transport sublayer may be selected from compounds represented by formula (4-1) to formula (4-2):

[0135] Among them, X 401 To X 408 are independently selected from C or N.

[0136] R 401 to R 408 and are each independently selected from hydrogen, deuterium, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted heterocycloalkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkenyl group having 3 to 10 carbon atoms, a substituted or unsubstituted heterocycloalkenyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 60 carbon atoms, a substituted or unsubstituted heteroaryl group having 1 to 60 carbon atoms, a substituted or unsubstituted non-aromatic fused polycyclic group, and a substituted or unsubstituted non-aromatic fused heteropolycyclic group.

[0137] In some embodiments, the material of the electron transport sublayer is selected from the following compounds:

[0138] In some embodiments, the electron mobility of the first n-type charge generation layer 105a is greater than or equal to 10 -5 cm2 / Vs, the electron mobility of the first buffer layer 104 is less than 10 -3 cm 2 / Vs, the electron mobility of the second buffer layer 106 is less than 10 -3 cm 2 / Vs, for example, the electron mobility of the first buffer layer 104 or the second buffer layer 106 may be 2×10 -5 cm 2 / Vs、4×10 -5 cm 2 / Vs、5×10 -5 cm 2 / Vs、10 -4 cm 2 / Vs, 2×10 -4 cm 2 / Vs、4×10 -4 cm 2 / Vs、5×10 -4 cm 2 / Vs、6×10 -4 cm 2 / Vs、8×10 -4 cm 2 / Vs, etc., the provision of the second buffer layer 106 improves the reverse charge sensitivity generated by the direct contact between the first n-type charge generation layer 105a and the first p-type charge generation layer 105b, thereby improving the working stability of the display panel 10 at high temperatures.

[0139] Preferably, the electron mobility of the first electron transport layer 112 is greater than 10 -5 cm 2 / Vs, the electron mobility of the first electron transport layer 112 is less than 10 -3 cm 2 / Vs, the electron mobility of the first buffer layer 104 is greater than 10 -5 cm 2 / Vs, for example, can be 2×10 -5 cm 2 / Vs、4×10 -5 cm 2 / Vs、5×10 -5 cm 2 / Vs, 10 -4 cm 2 / Vs, 2×10 -4 cm 2 / Vs、4×10 -4 cm 2 / Vs、5×10 -4 cm2 / Vs、6×10 -4 cm 2 / Vs、8×10 -4 cm 2 / Vs, etc. The first electron transport layer 112 that is in direct contact with the first buffer layer 104 may be the first electron transport sublayer. By aligning the electron mobility range of the first buffer layer 104 with the electron mobility range of the first electron transport sublayer, it is helpful to avoid that the provision of the first buffer layer 104 reduces the migration rate of electrons from the first n-type charge generation layer 105a to the first light-emitting unit 109.

[0140] In some embodiments, the material of the second buffer layer 106 is the same as that of the first buffer layer 104 , which helps to simplify the manufacturing process of the first buffer layer 104 and the second buffer layer 106 and facilitates the production of the display panel 10 .

[0141] The first buffer layer 104, the second buffer layer 106 and the first n-type charge generation layer 105a need to be formed by an evaporation process. When only the second buffer layer 106 is formed, even if the material of the second buffer layer 106 is the same as the first electron transport material, it is still necessary to add an evaporation cycle of separately evaporating the first electron transport material after the original evaporation process cycle of forming the first n-type charge generation layer 105a to form the second buffer layer 106 located between the first n-type charge generation layer 105a and the first p-type charge generation layer 105b, and the process is more complicated; when the material of the first buffer layer 104 and the material of the second buffer layer 106 are the same but different from the first electron transport material of the first n-type charge generation layer 105a, it is necessary to add an evaporation chamber to form the first buffer layer 104 and the second buffer layer 106, and the process is more complicated and the cost is higher; when the material of the first buffer layer 104, the material of the second buffer layer 106, the material of the first n-type charge generation layer 105a ... When the first electron transport material of the generation layer 105a is the same, the original complete co-evaporation of the first electron transport material and the first charge doping material can be changed to incomplete co-evaporation in one evaporation process cycle of the original evaporation to form the first n-type charge generation layer 105a: first, a part of the first electron transport material is evaporated to form one of the first buffer layer 104 and the second buffer layer 106, and then the first electron transport material and the first charge doping material are co-evaporated to form the first n-type charge generation layer 105a, and finally, a part of the first electron transport material is evaporated to form the other of the first buffer layer 104 and the second buffer layer 106. In this way, the first buffer layer 104, the second buffer layer 106 and the first n-type charge generation layer 105a can be formed in the same evaporation chamber without increasing the evaporation cycle, which is beneficial to simplifying the process. Therefore, preferably, the material of the second buffer layer 106, the material of the first buffer layer 104 and the first electron transport material are the same. In one cycle of evaporating the first n-type charge generation layer 105a, only incomplete co-evaporation of the first electron transport material and the first charge doping material is required to form the second buffer layer 106 and the first buffer layer 104. The process is further simplified, which facilitates the production of the display panel 10.

[0142] When the material of the second buffer layer 106 is the same as the material of the first buffer layer 104 and the first electron transport material, the difference between the thickness of the second buffer layer 106 and the thickness of the first buffer layer 104 is greater than or equal to 0 angstroms, and the difference between the thickness of the second buffer layer 106 and the thickness of the first buffer layer 104 is less than or equal to 50 angstroms, for example, 5 angstroms, 10 angstroms, 15 angstroms, 20 angstroms, 25 angstroms, 30 angstroms, 35 angstroms, 40 angstroms, 45 angstroms, etc. Preferably, the difference between the thickness of the second buffer layer 106 and the thickness of the first buffer layer 104 is 0 angstroms, that is, the thickness of the second buffer layer 106 is the same as the thickness of the first buffer layer 104.

[0143] When the material of the second buffer layer 106 is the same as that of the first buffer layer 104, the electron mobility range of the second buffer layer 106 is the same as that of the first buffer layer 104, that is, the electron mobility of the second buffer layer 106 is greater than 10 -5 cm 2 / Vs, the electron mobility of the second buffer layer 106 is less than 10 -3 cm 2 / Vs, for example, can be 2×10 -5 cm 2 / Vs、4×10 -5 cm 2 / Vs、5×10 -5 cm 2 / Vs, 10 -4 cm 2 / Vs, 2×10 -4 cm 2 / Vs、4×10 -4 cm 2 / Vs、5×10 -4 cm 2 / Vs、6×10 -4 cm 2 / Vs、8×10 -4 cm 2 / Vs, etc.

[0144] In some embodiments, the difference between the highest occupied molecular orbital energy level of the first buffer layer 104 and the lowest unoccupied molecular orbital energy level of the first n-type charge generation layer 105a is greater than 2eV, and the difference between the highest occupied molecular orbital energy level of the first buffer layer 104 and the lowest unoccupied molecular orbital energy level of the first n-type charge generation layer 105a is less than 4eV, for example, can be 2.2eV, 2.5eV, 2.7eV, 3eV, 3.2eV, 3.4eV, 3.5eV, 3.6eV, 3.8eV, etc. The difference between the energy levels of the first buffer layer 104 and the first n-type charge generation layer 105a is kept within a suitable range, which is conducive to the electrons from the first n-type charge generation layer 105a to the first buffer layer 105a. The p-type charge generation layer 105b is transferred to the first light-emitting unit 109 by the buffer layer 104; the difference between the highest occupied molecular orbital energy level of the second buffer layer 106 and the lowest unoccupied molecular orbital energy level of the first n-type charge generation layer 105a is greater than 2eV, and the difference between the highest occupied molecular orbital energy level of the second buffer layer 106 and the lowest unoccupied molecular orbital energy level of the first n-type charge generation layer 105a is less than 4eV, for example, it can be 2.2eV, 2.5eV, 2.7eV, 3eV, 3.2eV, 3.4eV, 3.5eV, 3.6eV, 3.8eV, etc., so that the electrons generated by the first p-type charge generation layer 105b can be more easily transferred to the first n-type charge generation layer 105a through the second buffer layer 106.

[0145] In some embodiments, the difference between the highest occupied molecular orbital energy level of the first buffer layer 104 and the lowest unoccupied molecular orbital energy level of a layer in contact with the first buffer layer 104 in the first electron transport layer 112 is less than or equal to 2 eV, and the difference between the highest occupied molecular orbital energy level of the first buffer layer 104 and the lowest unoccupied molecular orbital energy level of a layer in contact with the first buffer layer 104 in the first electron transport layer 112 is greater than or equal to 4 eV, for example, it can be 2.2 eV, 2.5 eV, 2.7 eV, 3 eV, 3.2 eV, 3.4 eV, 3.5 eV, 3.6 eV, 3.8 eV, etc., so that electrons can be more easily transferred from the first buffer layer 104 to the first electron transport layer 112.

[0146] In some embodiments, the difference between the absolute value of the lowest unoccupied molecular orbital energy level of the first n-type charge generation layer 105a and the absolute value of the highest occupied molecular orbital energy level of the first p-type charge generation layer 105b is less than or equal to 3.5 eV. For example, it can be 1 eV, 1.5 eV, 2 eV, 2.5 eV, 3 eV, etc., which is conducive to the transfer of electrons from the first p-type charge generation layer 105b to the first n-type charge generation layer 105a.

[0147] In some embodiments, the absolute value of the lowest unoccupied molecular orbital energy level of the first n-type charge generation layer 105a is greater than or equal to 2.5 eV, and the absolute value of the lowest unoccupied molecular orbital energy level of the first n-type charge generation layer 105a is less than or equal to 4.5 eV, for example, 2.8 eV, 3 eV, 3.2 eV, 3.5 eV, 3.6 eV, 3.8 eV, 4 eV, 4.2 eV, etc.

[0148] In some embodiments, the absolute value of the highest occupied molecular orbital energy level of the first p-type charge generation layer 105b is greater than or equal to 4.5 eV, and the absolute value of the highest occupied molecular orbital energy level of the first p-type charge generation layer 105b is less than or equal to 6.5 eV, for example, it can be 4.8 eV, 5 eV, 5.2 eV, 5.5 eV, 5.6 eV, 5.8 eV, 6 eV, 6.2 eV, etc.

[0149] In some embodiments, the electron work function of the first buffer layer 104 is between the electron work function of the first n-type charge generation layer 105a and the electron work function of the first p-type charge generation layer 105b, and the electron work function of the second buffer layer 106 is between the electron work function of the first n-type charge generation layer 105a and the electron work function of the first p-type charge generation layer 105b.

[0150] In some embodiments, the electron work function of the first buffer layer 104 is greater than 5.5 eV, and the electron work function of the first buffer layer 104 is less than 7.5 eV, for example, 6 eV, 6.2 eV, 6.5 eV, 6.7 eV, 7 eV, 7.2 eV, etc.

[0151] In some embodiments, the electron work function of the first electron transport layer 112 is greater than 5.5 eV, and the electron work function of the first electron transport layer 112 is less than 7.5 eV. The electron work function of the first buffer layer 104 is controlled to be in the same range as the electron work function of the first electron transport layer 112, so as to reduce the interference of the setting of the first buffer layer 104 on the movement of electrons.

[0152] In some embodiments, the electron work function of the second buffer layer 106 is greater than 5.5 eV, and the electron work function of the second buffer layer 106 is less than 7.5 eV, for example, 6 eV, 6.2 eV, 6.5 eV, 6.7 eV, 7 eV, 7.2 eV, etc.

[0153] The first p-type charge generation layer 105 b includes a first hole transport material, and the third buffer layer 115 includes a second hole transport material.

[0154] In some embodiments, the first hole transport material and the second hole transport material are selected from at least one of aniline derivatives, diphenylamine derivatives, triphenylamine derivatives, carbazole derivatives, furan derivatives, and thiophene derivatives.

[0155] In some embodiments, the first hole transport material and the second hole transport material are independently selected from a material having a structure as shown in any one of formulas (5-1) to (5-4):

[0156] Among them, R 501 to R 507 、R 511 to R 513 、R 521 to R 523 、R 511 to R 533 and each is independently selected from hydrogen, deuterium, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted heterocycloalkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkenyl group having 3 to 10 carbon atoms, a substituted or unsubstituted heterocycloalkenyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 60 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 60 carbon atoms, a substituted or unsubstituted arylthio group having 6 to 60 carbon atoms, a substituted or unsubstituted heteroaryl group having 5 to 60 carbon atoms, a substituted or unsubstituted non-aromatic fused polycyclic group, and a substituted or unsubstituted non-aromatic fused heteropolycyclic group.

[0157] The third buffer layer 115 is in direct contact with the second hole transport sublayer in the second hole transport layer 113 .

[0158] The material selection range of the second hole transport sublayer may be the same as or different from the selection range of the first hole transport material and the second hole transport material.

[0159] In some embodiments, the material of the second hole transport sublayer, the first hole transport material, and the second hole transport material are independently selected from the following compounds:

[0160] In some embodiments, the third buffer layer 115 is composed of the second hole transport material, and the second hole transport material is the same as the first hole transport material.

[0161] In some embodiments, the fourth buffer layer 116 is composed of the second hole transport material.

[0162] In some embodiments, the third buffer layer 115 and the fourth buffer layer 116 have the same material composition, and both have the same first hole transport material.

[0163] In some embodiments, the first p-type charge generation layer 105b further includes a second charge-doping material. The first p-type charge generation layer 105b may be composed of the second hole transport material and the second charge-doping material. The addition of the second charge-doping material is beneficial to improving the hole mobility of the first p-type charge generation layer 105b. Preferably, the mass ratio of the second hole transport material to the second charge-doping material is 99:1 to 80:20, for example, 98:2, 95:5, 92:8, 90:10, 88:12, 85:15, 82:18, etc.

[0164] In some embodiments, the second charge-doping material may be selected from at least one of a quinone derivative, a metal oxide, and a cyano-containing compound.

[0165] In some embodiments, the second charge-doping material can be selected from at least one of tetracyanoquinodimethane (TCNQ), 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ), tungsten oxide, molybdenum oxide, and 1,4,5,8,9,12-hexaazatriphenylene-hexanitrile (HAT-CN).

[0166] In some embodiments, the second charge-doping material is selected from compounds represented by any one of formulas (6-1) to (6-3):

[0167] Among them, X 601 To X 603 are independently selected from C, O, and N;

[0168] R 601 to R 613 and each is independently selected from a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted heterocycloalkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkenyl group having 3 to 10 carbon atoms, a substituted or unsubstituted heterocycloalkenyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 60 carbon atoms, a substituted or unsubstituted heteroaryl group having 5 to 60 carbon atoms, a substituted or unsubstituted non-aromatic fused polycyclic group, a substituted or unsubstituted non-aromatic fused heteropolycyclic group, a cyano group, -F, -Cl, -Br, -I, an alkyl group having 1 to 20 carbon atoms substituted by -F, an alkyl group having 1 to 20 carbon atoms substituted by -Cl, an alkyl group having 1 to 20 carbon atoms substituted by -Br, and an alkyl group having 1 to 20 carbon atoms substituted by -I.

[0169] In some embodiments, the hole mobility of the first p-type charge generation layer 105b is greater than or equal to 10 -2 cm 2 / Vs, the hole mobility of the third buffer layer 115 is greater than 10 -4 cm 2 / Vs, the hole mobility of the fourth buffer layer 116 is less than 10 -4 cm 2 / Vs, the provision of the third buffer layer 115 and the fourth buffer layer 116 further improves the reverse charge sensitivity generated by the direct contact between the first n-type charge generation layer 105a and the first p-type charge generation layer 105b, thereby improving the working stability of the display panel 10 at high temperatures.

[0170] Preferably, the hole mobility of the second hole transport layer 113 is greater than 10 -4 cm 2 / Vs, the hole mobility of the second hole transport layer 113 is less than 10 -2 cm 2 / Vs, the hole mobility of the third buffer layer 115 is greater than 10 -4 cm 2 / Vs, for example, the hole mobility of the third buffer layer 115 may be 2×10 -4 cm 2 / Vs、4×10 -4 cm 2 / Vs、5×10 -4 cm 2 / Vs, 10 -3 cm 2 / Vs, 2×10 -3 cm 2 / Vs、4×10 -3 cm 2 / Vs、5×10 -3 cm 2 / Vs、6×10 -3 cm 2 / Vs、8×10 -3 cm 2 / Vs, etc. The portion of the second hole transport layer 113 that is in direct contact with the third buffer layer 115 may be the second hole transport sublayer. By aligning the hole mobility range of the third buffer layer 115 with the hole mobility range of the second hole transport sublayer, it is helpful to avoid the provision of the third buffer layer 115 reducing the migration rate of holes from the first p-type charge generation layer 105b to the second light-emitting unit 110.

[0171] In some embodiments, the material of the fourth buffer layer 116 is the same as that of the third buffer layer 115 , which helps to simplify the manufacturing process of the fourth buffer layer 116 and the third buffer layer 115 and facilitates the production of the display panel 10 .

[0172] The fourth buffer layer 116, the third buffer layer 115 and the first p-type charge generation layer 105b need to be formed by an evaporation process. When only the fourth buffer layer 116 is formed, even if the material of the fourth buffer layer 116 is the same as the first hole transport material, it is still necessary to add an evaporation cycle of separately evaporating the first hole transport material after the original evaporation process cycle of forming the first p-type charge generation layer 105b to form the fourth buffer layer 116 located between the first n-type charge generation layer 105a and the first p-type charge generation layer 105b, and the process is more complicated; when the material of the fourth buffer layer 116 and the material of the third buffer layer 115 are the same but different from the first hole transport material of the first p-type charge generation layer 105b, it is necessary to add an evaporation chamber to form the fourth buffer layer 116 and the third buffer layer 115, and the process is more complicated and the cost is higher; when the material of the fourth buffer layer 116, the material of the third buffer layer 115, the material of the first p-type charge generation layer 105b When the first hole transport material of the generation layer 105b is the same, the original complete co-evaporation of the first hole transport material and the second charge doping material can be changed to incomplete co-evaporation in an evaporation process cycle for forming the first p-type charge generation layer 105b: first, part of the first hole transport material is evaporated to form the fourth buffer layer 116 and one of the third buffer layer 115, and then the first hole transport material and the second charge doping material are co-evaporated to form the first p-type charge generation layer 105b, and finally, part of the first hole transport material is evaporated to form the other of the fourth buffer layer 116 and the third buffer layer 115. In this way, the fourth buffer layer 116, the third buffer layer 115 and the first p-type charge generation layer 105b can be formed in the same evaporation chamber without increasing the evaporation cycle, which is beneficial to simplifying the process. Therefore, preferably, the material of the fourth buffer layer 116, the material of the third buffer layer 115 and the first hole transport material are the same. In one cycle of evaporating the first p-type charge generation layer 105b, only the second hole transport material and the second charge doping material need to be incompletely co-evaporated to form the fourth buffer layer 116 and the third buffer layer 115. The process is further simplified, which facilitates the production of the display panel 10.

[0173] When the material of the fourth buffer layer 116, the material of the third buffer layer 115, and the first hole transport material are the same, the difference between the thickness of the fourth buffer layer 116 and the thickness of the third buffer layer 115 is greater than or equal to 0 angstrom, and the difference between the thickness of the fourth buffer layer 116 and the thickness of the third buffer layer 115 is less than or equal to 50 angstroms, for example, 5 angstroms, 10 angstroms, 15 angstroms, 20 angstroms, 25 angstroms, 30 angstroms, 35 angstroms, 40 angstroms, 45 angstroms, etc. Preferably, the difference between the thickness of the fourth buffer layer 116 and the thickness of the third buffer layer 115 is 0 angstrom, that is, the thickness of the fourth buffer layer 116 is the same as the thickness of the third buffer layer 115.

[0174] When the material of the fourth buffer layer 116 is the same as that of the third buffer layer 115, the hole mobility range of the fourth buffer layer 116 is the same as that of the third buffer layer 115, that is, the hole mobility of the fourth buffer layer 116 is greater than 10 -4 cm 2 / Vs, the hole mobility of the fourth buffer layer 116 is less than 10 -2 cm 2 / Vs, for example, can be 2×10 -4 cm 2 / Vs、4×10 -4 cm 2 / Vs、5×10 -4 cm 2 / Vs, 10 -3 cm 2 / Vs, 2×10 -3 cm 2 / Vs、4×10 -3 cm 2 / Vs、5×10 -3 cm 2 / Vs、6×10 -3 cm 2 / Vs、8×10 -3 cm 2 / Vs, etc.

[0175] In some embodiments, the electron mobility of the first buffer layer 104, the second buffer layer 106, the layer of the first electron transport layer 112 that is in direct contact with the first buffer layer 104, and the first n-type charge generation layer 105a, and the hole mobility of the first p-type charge generation layer 105b, the third buffer layer 115, the fourth buffer layer 116, and the layer of the second hole transport layer 113 that is in direct contact with the third buffer layer 115 can be obtained through SCLC (Space-Charge-Limited-Current) testing. Specifically, the test results are combined with the Mott-Gurney equation and the Frenkel effect: Taking the logarithm of both sides gives: It can be seen that there is a linear relationship between In(J / E2) and . The function graph of In(J / E2) is plotted as it changes. The zero-field mobility of carriers in organic materials is calculated based on the intercept of the straight line. After being substituted into the Poole-Frenkel formula, the field-dependent mobility of carriers under a fixed electric field can be obtained.

[0176] In some embodiments, the difference between the lowest unoccupied molecular orbital energy level of the third buffer layer 115 and the highest occupied molecular orbital energy level of the first p-type charge generation layer 105 b is greater than 2 eV, and the difference between the lowest unoccupied molecular orbital energy level of the third buffer layer 115 and the highest occupied molecular orbital energy level of the first p-type charge generation layer 105 b is less than 4 eV, for example, can be 2.2 eV, 2.5 eV, 2.7 eV, 3 eV, 3.2 eV, 3.4 eV, 3.5 eV, 3.6 eV, 3.8 eV, etc., so as to keep the energy level difference between the first p-type charge generation layer 105 b and the third buffer layer 115 within a suitable range, which is conducive to the transfer of electrons from the third buffer layer 115 to the first p-type charge generation layer 105 b, accordingly, holes are transferred from the first p-type charge generation layer 105b to the third buffer layer 115; the difference between the lowest unoccupied molecular orbital energy level of the fourth buffer layer 116 and the highest occupied molecular orbital energy level of the first p-type charge generation layer 105b is greater than 2eV, and the difference between the lowest unoccupied molecular orbital energy level of the fourth buffer layer 116 and the highest occupied molecular orbital energy level of the first p-type charge generation layer 105b is less than 4eV, for example, it can be 2.2eV, 2.5eV, 2.7eV, 3eV, 3.2eV, 3.4eV, 3.5eV, 3.6eV, 3.8eV, etc., so as to facilitate the transfer of electrons from the first p-type charge generation layer 105b to the first n-type charge generation layer 105a via the fourth buffer layer 116.

[0177] In some embodiments, the difference between the lowest unoccupied molecular orbital energy level of the third buffer layer 115 and the highest occupied molecular orbital energy level of a layer in the second hole transport layer 113 that is in direct contact with the third buffer layer 115 is greater than or equal to 2eV, and the difference between the lowest unoccupied molecular orbital energy level of the third buffer layer 115 and the highest occupied molecular orbital energy level of a layer in the second hole transport layer 113 that is in direct contact with the third buffer layer 115 is less than or equal to 4eV, for example, it can be 2.2eV, 2.5eV, 2.7eV, 3eV, 3.2eV, 3.4eV, 3.5eV, 3.6eV, 3.8eV, etc., so as to facilitate the transmission of electrons from the second hole transport layer 113 to the third buffer layer 115, and correspondingly, holes are transmitted from the third buffer layer 115 to the second hole transport layer 113.

[0178] In some embodiments, the lowest unoccupied molecular orbital energy level and the highest occupied molecular orbital energy level of the first buffer layer 104, the second buffer layer 106, the third buffer layer 115, the fourth buffer layer 116, the first n-type charge generation layer 105a, the first p-type charge generation layer 105b, a layer of the first electron transport layer 112 that is in direct contact with the first buffer layer 104, and a layer of the second hole transport layer 113 that is in direct contact with the third buffer layer 115 can be obtained by electrochemical methods (e.g., electrochemical cyclic voltammetry), ultraviolet photoelectron spectroscopy, etc. It is understood that the difference between the lowest unoccupied molecular orbital energy level and the highest occupied molecular orbital energy level is the difference between the lowest unoccupied molecular orbital energy level and the highest occupied molecular orbital energy level obtained under the same experimental method and experimental conditions.

[0179] In some embodiments, the electron work function of the third buffer layer 115 is greater than 5.5 eV, and the electron work function of the third buffer layer 115 is less than 7.5 eV, for example, 6 eV, 6.2 eV, 6.5 eV, 6.7 eV, 7 eV, 7.2 eV, etc.

[0180] In some embodiments, the electron work function of the second hole transport layer 113 is greater than 5.5 eV, and the electron work function of the second hole transport layer 113 is less than 7.5 eV. The electron work function of the third buffer layer 115 is controlled to be in the same range as the electron work function of the second hole transport layer 113, so as to reduce the interference of the setting of the third buffer layer 115 on the movement of holes.

[0181] In some embodiments, the electron work function of the fourth buffer layer 116 is greater than 5.5 eV, and the electron work function of the fourth buffer layer 116 is less than 7.5 eV, for example, 6 eV, 6.2 eV, 6.5 eV, 6.7 eV, 7 eV, 7.2 eV, etc.

[0182] In some embodiments, the electron work functions of the first buffer layer 104, the second buffer layer 106, the first n-type charge generation layer 105a, the first p-type charge generation layer 105b, the first electron transport layer 112, the third buffer layer 115, the fourth buffer layer 116, and the second hole transport layer 113 can be obtained by respectively testing the photoelectron spectra of the above-mentioned film layers, such as X-ray photoelectron spectroscopy and / or ultraviolet photoelectron spectroscopy.

[0183] In some embodiments, the display panel 10 includes a plurality of light emitting elements 100 , and the plurality of light emitting elements 100 can emit red, green, and blue light, respectively.

[0184] Referring to FIG. 6 , in some embodiments, the display panel 10 further includes an array substrate 200 located on one side of the light emitting element 100 , and an encapsulation layer 300 located on a side of the light emitting element 100 away from the array substrate 200 and covering the light emitting element 100 .

[0185] The display panel 10 further includes a polarizer layer 400 located on a side of the encapsulation layer 300 away from the light-emitting element 100, and a cover layer 500 located on a side of the polarizer layer 400 away from the light-emitting element 100. The polarizer layer 400 may be replaced by a color filter layer, which may include multiple color resists and a black matrix located on both sides of the color resists.

[0186] The display panel 10 provided in the present application provides a first buffer layer 104 and a second buffer layer 106 on opposite sides of the first n-type charge generation layer 105a. The electron mobility of the first buffer layer 104 and the second buffer layer 106 is lower than that of the first n-type charge generation layer 105a. This improves the reverse charge sensitivity generated by the direct contact between the first n-type charge generation layer 105a and the first p-type charge generation layer 105b, and acts as a hole blocking layer between the first n-type charge generation layer 105a and the first light-emitting layer 103, thereby improving the operating stability of the display panel 10 at high temperatures.

[0187] The following is a comparison of several groups of light-emitting elements for illustration.

[0188] Example 1

[0189] Light-emitting element 1

[0190] The light-emitting element 1 is formed by stacking an anode, a hole injection sublayer, a hole transport sublayer, an electron blocking sublayer, a blue light-emitting layer, a hole blocking layer, an electron transport sublayer, a first buffer layer, a first n-type charge generation layer, a second buffer layer, a first p-type charge generation layer, a hole transport sublayer, an electron blocking sublayer, a blue light-emitting layer, a hole blocking sublayer, an electron transport sublayer, an electron injection sublayer and a cathode in sequence.

[0191] The material of the anode is selected from indium tin oxide; the cathode is a mixed electrode of Mg and Ag, wherein the mass ratio of Mg to Ag is 10:90;

[0192] The thickness of the electron injection sublayer is 1 nm and the material is Yb;

[0193] The thickness of the electron transport sublayer is 20 nm, and the material is selected from a mixture of ET5 and Liq, with a mass ratio of 50:50;

[0194] The thickness of the hole blocking sublayer is 5 nm, and the material is selected from ET6;

[0195] The thickness of the light-emitting layer is 20 nm, and the material is selected from a mixture of BH16 and BD3, with a mass ratio of BH16 to BD3 of 98:2;

[0196] The thickness of the electron blocking sublayer is 5 nm, and the material is selected from TCTA;

[0197] The thickness of the hole transport sublayer is 25 nm and the material is selected from TAPC;

[0198] The thickness of the first buffer layer and the second buffer layer are both 0.5nm, the material is selected from E19, and the electron mobility of the first buffer layer and the second buffer layer are 3.0x10 -4 cm 2 / Vs, the electron work functions of the first buffer layer and the second buffer layer are respectively about 6.2 eV;

[0199] The first n-type charge generation layer is an n-type charge generation sublayer with a thickness of 9 nm and a material of a mixture of E19 and Yb, wherein Yb is a charge doping material and the mass ratio of E19 to Yb is 98:2;

[0200] The first p-type charge generation layer is a p-type charge generation sublayer with a thickness of 10 nm, and the material is selected from a mixture of PD1 and TAPC, and the mass ratio of TAPC to PD1 is 90:10;

[0201] The thickness of the hole injection sublayer is 10 nm, and the material is selected from a mixture of TAPC and PD1, and the mass ratio of TAPC to PD1 is 97:3.

[0202] Example 2

[0203] Light-emitting element 2

[0204] Same as or similar to light emitting element 1, except that:

[0205] The thickness of the first buffer layer and the second buffer layer is 1 nm respectively, and the thickness of the first n-type charge generation layer is 8 nm.

[0206] Example 3

[0207] Light-emitting element 3

[0208] Same as or similar to light emitting element 1, except that:

[0209] The thickness of the first buffer layer and the second buffer layer is 1.5 nm respectively, and the thickness of the first n-type charge generation layer is 7 nm.

[0210] Example 4

[0211] Light emitting element 4

[0212] Identical or similar to a light-emitting element, except that:

[0213] The light-emitting element 1 is formed by stacking an anode, a hole injection sublayer, a hole transport sublayer, an electron blocking sublayer, a blue light-emitting layer, a hole blocking layer, an electron transport sublayer, a first n-type charge generation layer, a fourth buffer layer, a first p-type charge generation layer, a third buffer layer, a hole transport sublayer, an electron blocking sublayer, a blue light-emitting layer, a hole blocking sublayer, an electron transport sublayer, an electron injection sublayer and a cathode in sequence.

[0214] The thickness of the first p-type charge generation layer is 8 nm, and the material of the first p-type charge generation layer is selected from a mixture of PD1 and TAPC, and the mass ratio of TAPC to PD1 is 90:10;

[0215] The thickness of the first n-type charge generation layer is 10 nm. The material of the first n-type charge generation layer is selected from a mixture of E19 and Yb, wherein Yb is a charge doping material, and the mass ratio of E19 to Yb is 98:2.

[0216] The thickness of the third buffer layer and the fourth buffer layer are 1 nm, the material is selected from TAPC, and the hole mobility of the third buffer layer and the fourth buffer layer are 1.5x10 -3 cm 2 / Vs, the electron work functions of the third buffer layer and the fourth buffer layer are respectively about 5.5 eV.

[0217] Example 5

[0218] Light-emitting element 5

[0219] Same as or similar to light emitting element 2, except that:

[0220] The light-emitting element 1 is formed by stacking an anode, a hole injection sublayer, a hole transport sublayer, an electron blocking sublayer, a blue light-emitting layer, a hole blocking layer, an electron transport sublayer, a first buffer layer, a first n-type charge generation layer, a fourth buffer layer, a first p-type charge generation layer, a third buffer layer, a hole transport sublayer, an electron blocking sublayer, a blue light-emitting layer, a hole blocking sublayer, an electron transport sublayer, an electron injection sublayer and a cathode in sequence.

[0221] The thickness of the first p-type charge generation layer was 8 nm.

[0222] The thickness of the third buffer layer and the fourth buffer layer are 1 nm respectively. The material is selected from TAPC. The hole mobility of the third buffer layer and the fourth buffer layer are 1.5x10 -3 cm 2 / Vs, and the electron work functions of the third buffer layer and the fourth buffer layer are respectively about 5.5 eV.

[0223] Comparative Example 1

[0224] Comparative Component 1

[0225] Same as or similar to light emitting element 1, except that:

[0226] Comparative element 1 is formed by stacking an anode, a hole injection sublayer, a hole transport sublayer, an electron blocking sublayer, a blue light-emitting layer, a hole blocking layer, an electron transport sublayer, a first n-type charge generation layer, a first p-type charge generation layer, a hole transport sublayer, an electron blocking sublayer, a blue light-emitting layer, a hole blocking sublayer, an electron transport sublayer, an electron injection sublayer and a cathode in sequence.

[0227] The thickness of the first n-type charge generation layer is 10 nm, and the electron mobility of the first n-type charge generation layer is 1.1x10 -2 cm 2 / Vs, the electron work function of the first n-type charge generation layer is about 3.0 eV; the thickness of the first p-type charge generation layer is 10 nm, and the hole mobility of the first p-type charge generation layer is 2.1x10 -2 cm 2 / Vs, the electron work function is about 5.2eV.

[0228] For light-emitting elements 1-5 and comparative element 1, the driving voltage, current efficiency, time for the luminance to decrease to 95% of the initial brightness under the same initial brightness conditions (T95 service life at the same brightness), and the current density (10 mA / cm 2 ) and working temperature (80℃) conditions after 100 hours of luminescence compared with the driving voltage drift recorded at room temperature. The results are shown in Table 1.

[0229] Table 1

[0230] According to the results in Table 1, by providing the first buffer layer and the second buffer layer, the driving voltage drift of the light-emitting element under high-temperature operation is effectively improved while maintaining the current efficiency and service life; the addition of the third buffer layer and the fourth buffer layer further reduces the driving voltage drift of the light-emitting element under high-temperature operation on the basis of the improvements of the first buffer layer and the second buffer layer, thereby improving the operating stability of the light-emitting element.

[0231] An embodiment of the present application discloses a display panel, wherein a light-emitting element of the display panel includes a first electrode layer, a first light-emitting layer, a first buffer layer, a first charge generation layer, a second buffer layer, a second light-emitting layer and a second electrode layer, wherein the first charge generation layer includes a first n-type charge generation layer and a first p-type charge generation layer, and the electron mobility of the first buffer layer and the electron mobility of the second buffer layer are both less than the electrical mobility of the first n-type charge generation layer; the present application improves the reverse charge sensitivity generated by direct contact between the first n-type charge generation layer and the first p-type charge generation layer, and plays a role in blocking holes between the first n-type charge generation layer and the first light-emitting layer, thereby improving the operating stability of the display panel at high temperatures.

[0232] It is understandable that those skilled in the art can make equivalent substitutions or changes based on the technical solution and inventive concept of this application, and all these changes or substitutions should fall within the scope of protection of the claims attached to this application.

Claims

1. A display panel, characterized in that: include: substrate; A first electrode layer, disposed on one side of the substrate; A first light-emitting layer is arranged on a side of the first electrode layer away from the substrate; A first buffer layer is arranged on a side of the first light-emitting layer away from the substrate; A first charge generation layer is arranged on a side of the first buffer layer away from the substrate, the first charge generation layer comprising: a first n-type charge generation layer arranged on a side of the first buffer layer away from the substrate and a first p-type charge generation layer arranged on a side of the first n-type charge generation layer away from the substrate; a second buffer layer disposed between the first n-type charge generation layer and the first p-type charge generation layer; A second light-emitting layer is disposed on a side of the first charge generating layer away from the substrate; A second electrode layer is arranged on a side of the second light-emitting layer away from the substrate; wherein the electron mobility of the first buffer layer is smaller than the electron mobility of the first n-type charge generation layer, and the electron mobility of the second buffer layer is smaller than the electron mobility of the first n-type charge generation layer; The difference between the highest occupied molecular orbital energy level of the first buffer layer and the lowest unoccupied molecular orbital energy level of the first n-type charge generation layer is greater than 2 eV, and the difference between the highest occupied molecular orbital energy level of the first buffer layer and the lowest unoccupied molecular orbital energy level of the first n-type charge generation layer is less than 4 eV; The difference between the highest occupied molecular orbital energy level of the second buffer layer and the lowest unoccupied molecular orbital energy level of the first n-type charge generation layer is greater than 2eV, and the difference between the highest occupied molecular orbital energy level of the second buffer layer and the lowest unoccupied molecular orbital energy level of the first n-type charge generation layer is less than 4eV.

2. The display panel according to claim 1, characterized in that: The display panel further includes a first electron transport layer located between the first light-emitting layer and the first buffer layer, wherein a side of the first buffer layer close to the first n-type charge generation layer is in direct contact with the first n-type charge generation layer, and a side of the first buffer layer far from the first n-type charge generation layer is in direct contact with the first electron transport layer; A side of the second buffer layer close to the first n-type charge generation layer is in direct contact with the first n-type charge generation layer, and a side of the second buffer layer far from the first n-type charge generation layer is in direct contact with the first p-type charge generation layer.

3. The display panel according to claim 2, characterized in that: The difference between the highest occupied molecular orbital energy level of the first buffer layer and the lowest unoccupied molecular orbital energy level of the first electron transport layer is greater than 2eV, and the difference between the highest occupied molecular orbital energy level of the first buffer layer and the lowest unoccupied molecular orbital energy level of the first electron transport layer is less than 4eV.

4. The display panel according to claim 2, characterized in that: The electron mobility of the first n-type charge generation layer is greater than or equal to 10 -3 cm 2 / Vs, the electron mobility of the first buffer layer is less than 10 -3 cm 2 / Vs, the electron mobility of the second buffer layer is less than 10 -3 cm 2 / Vs.

5. The display panel according to claim 4, characterized in that: The electron mobility of the first electron transport layer is greater than 10 -5 cm 2 / Vs, the electron mobility of the first electron transport layer is less than 10 -3 cm 2 / Vs, the electron mobility of the first buffer layer is greater than 10 -5 cm 2 / Vs, the electron mobility of the second buffer layer is greater than 10 -5 cm 2 / Vs.

6. The display panel according to claim 1, characterized in that: The electron work function of the first buffer layer is between the electron work functions of the first n-type charge generation layer and the first p-type charge generation layer, and the electron work function of the second buffer layer is between the electron work functions of the first n-type charge generation layer and the first p-type charge generation layer.

7. The display panel according to claim 6, characterized in that: The electron work function of the first buffer layer is greater than 5.5 eV, and the electron work function of the first buffer layer is less than 7.5 eV; The electron work function of the second buffer layer is greater than 5.5 eV, and the electron work function of the second buffer layer is less than 7.5 eV.

8. The display panel according to claim 1, characterized in that: The first n-type charge generation layer includes a first electron transport material and a first charge doping material, the first buffer layer is composed of the first electron transport material, and the second buffer layer is composed of the first electron transport material.

9. The display panel according to claim 8, characterized in that: A difference in thickness between the first buffer layer and the second buffer layer is greater than or equal to 0 angstroms, and a difference in thickness between the first buffer layer and the second buffer layer is less than or equal to 50 angstroms.

10. The display panel according to claim 8, characterized in that: In the first n-type charge generation layer, a mass ratio of the first electron transport material to the first charge doping material is 99:1 to 80:

20.

11. The display panel according to claim 1, characterized in that: The display panel further includes a third buffer layer and a fourth buffer layer, wherein the third buffer layer is located between the first p-type charge generation layer and the second light emitting layer, and the fourth buffer layer is located between the first p-type charge generation layer and the second buffer layer; The hole mobility of the third buffer layer is smaller than the hole mobility of the first p-type charge generation layer, and the hole mobility of the fourth buffer layer is smaller than the hole mobility of the first p-type charge generation layer.

12. The display panel according to claim 11, characterized in that: The difference between the lowest unoccupied molecular orbital energy level of the third buffer layer and the highest occupied molecular orbital energy level of the first p-type charge generation layer is greater than 2 eV, and the difference between the lowest unoccupied molecular orbital energy level of the third buffer layer and the highest occupied molecular orbital energy level of the first p-type charge generation layer is less than 4 eV; The difference between the lowest unoccupied molecular orbital energy level of the fourth buffer layer and the highest occupied molecular orbital energy level of the first p-type charge generation layer is greater than 2eV, and the difference between the lowest unoccupied molecular orbital energy level of the fourth buffer layer and the highest occupied molecular orbital energy level of the first p-type charge generation layer is less than 4eV.

13. The display panel according to claim 11, characterized in that: The display panel further includes a second hole transport layer located between the second light emitting layer and the third buffer layer, a side of the third buffer layer close to the first p-type charge generating layer is in direct contact with the first p-type charge generating layer, and a side of the third buffer layer far from the first p-type charge generating layer is in direct contact with the second hole transport layer; A side of the fourth buffer layer close to the second buffer layer is in direct contact with the second buffer layer, and a side of the fourth buffer layer far from the second buffer layer is in direct contact with the first p-type charge generation layer.

14. The display panel according to claim 13, characterized in that: The difference between the lowest unoccupied molecular orbital energy level of the third buffer layer and the highest occupied molecular orbital energy level of the second hole transport layer is greater than 2eV, and the difference between the lowest unoccupied molecular orbital energy level of the third buffer layer and the highest occupied molecular orbital energy level of the second hole transport layer is less than 4eV.

15. The display panel according to claim 13, characterized in that: The hole mobility of the first p-type charge generation layer is greater than or equal to 10 -2 cm 2 / Vs, the hole mobility of the third buffer layer is less than 10 -2 cm 2 / Vs, the hole mobility of the fourth buffer layer is less than 10 -2 cm 2 / Vs.

16. The display panel according to claim 15, characterized in that: The hole mobility of the second hole transport layer is greater than 10 -4 cm 2 / Vs, the hole mobility of the third buffer layer is greater than 10 -4 cm 2 / Vs, the hole mobility of the fourth buffer layer is greater than 10 -4 cm 2 / Vs.

17. The display panel according to claim 11, characterized in that: The electron work function of the third buffer layer is between the electron work functions of the first n-type charge generation layer and the first p-type charge generation layer, and the electron work function of the fourth buffer layer is between the electron work functions of the first n-type charge generation layer and the first p-type charge generation layer.

18. The display panel according to claim 17, characterized in that: The electron work function of the third buffer layer is greater than 5.5 eV, and the electron work function of the third buffer layer is less than 7.5 eV; The electron work function of the fourth buffer layer is greater than 5.5 eV, and the electron work function of the fourth buffer layer is less than 7.5 eV.

19. The display panel according to claim 11, characterized in that: The first p-type charge generation layer includes a first hole transport material and a second charge doping material, the third buffer layer is composed of the first hole transport material, and the fourth buffer layer is composed of the first hole transport material.

20. The display panel according to claim 19, characterized in that: A difference in thickness between the third buffer layer and the fourth buffer layer is greater than or equal to 0 angstrom, and a difference in thickness between the third buffer layer and the fourth buffer layer is less than or equal to 50 angstroms.

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