Full-color Micro-LED chip array based on red-light perovskite and preparation method thereof

Abstract

The invention discloses a full-color Micro-LED chip array based on red light perovskite and a preparation method of the full-color Micro-LED chip array, the array comprises a plurality of Micro-LED chips, each chip comprises a substrate and a blue light Micro-LED and a green light Micro-LED which are arranged on the substrate, and a red light perovskite Micro-LED is arranged at the position 0.1-100 microns away from the blue light Micro-LED and the green light Micro-LED. The perovskite red light Micro-LED can be directly prepared on a blue light Micro-LED array and a green light Micro-LED array, transfer integration is not needed, and the full-color Micro-LED chip array obtained through the method has the advantages of being lower in preparation cost, higher in color purity, free of an obvious side wall effect and higher in efficiency.

Description

Technical Field

[0001] The present invention relates to the field of display technology, and in particular to a red light perovskite integrated full-color Micro-LED chip array and a preparation method thereof. Background Art

[0002] Micro light-emitting diodes (micro LEDs) have been regarded as the next generation display technology, which has significant advantages in resolution, brightness and response time. As green and blue micro LEDs have achieved high-performance devices below 10μm in size, researchers have turned their research focus to red micro LEDs. Due to the formation of sidewall defects, red micro-LEDs exhibit serious size-dependent efficiency degradation problems (Red InGaN micro-light-emitting diodes (>620nm) with a peak external quantum efficiency of 4.5% using an epitaxial tunnel junction contact, Appl. Phys. Lett., 2022, 120, 121102; High-efficiency InGaN red micro-LEDs for visible light communication, Photonics Res., 2022, 10, 1978–1986; 2000PPI silicon-based AlGaInP red micro-LED arrays fabricated via wafer bonding and epilayer lift-off, Opt. Express, 2021, 29, 20217–20228; Size-dependent efficiency and efficiency droop of blue InGaN micro-light emitting diodes, Appl. Phys. Lett., 2012, 101, 231110). Previous studies have attempted to reduce non-radiative recombination centers through sidewall passivation, but the maximum external quantum efficiencies (EQEs) of red micro-LEDs achieved were only 5.25% and 5.02%, corresponding to pixel diameters of 50μm and 25μm, respectively (High-efficiency InGaN red micro-LEDs for visible light communication, Photonics Res., 2022, 10, 1978–1986), which limits their application in full-color displays.

[0003] Metal halide perovskites have attracted much attention due to their high photoluminescence quantum efficiency (PLQE), high charge mobility, and easy solution processing, and are considered promising for realizing efficient and bright micro-LEDs. In addition, the inherent polycrystalline nature of perovskite films limits their charge diffusion length, which helps to mitigate the impact of sidewall defects and is beneficial to the realization of efficient micro-LEDs. Although there have been attempts to manufacture red perovskite micro-LEDs using inkjet printing and screen printing methods (Microscale perovskite quantum dot light-emitting diodes (Micro-PeLEDs) for full-color displays, Adv. Opt. Mater., 2022, 10, 2200087; Ultrahigh color rendering in RGB perovskite micro-light-emitting diode arrays with resonance-enhanced photon recycling for next generation displays, Adv. Opt. Mater., 2022, 10, 2101642), the devices obtained by these methods have an EQE of less than 1% when the pixel diameters are 45μm and 20μm, respectively. This is mainly attributed to the lack of dense and uniform films with high PLQE. It is worth noting that lead halide perovskite materials can directly obtain high external quantum efficiency (EQE) under the micro-device structure by introducing effective passivators into the precursors to regulate the growth and crystallization process. Therefore, red perovskite materials integrated with full-color Micro-LED chip arrays have broad application prospects in the field of ultra-high-definition display technology. Summary of the invention

[0004] In view of the above problems, the purpose of the present invention is to provide a full-color Micro-LED chip array based on red light perovskite. The main feature of this display array is that it uses red light perovskite LEDs to replace traditional InGaN-based red light LEDs, and integrates them with III-V group blue and green light Micro-LEDs. The perovskite red light device has higher color purity and higher EQE than the traditional InGaN-based red light LED, and the EQE remains basically unchanged when the lateral size of the chip is reduced.

[0005] Another object of the present invention is to provide a method for preparing the above-mentioned red light perovskite full-color Micro-LED chip array.

[0006] The object of the present invention is achieved in the following ways:

[0007] The array includes a plurality of Micro-LED chips, each of which includes a substrate and blue and green light Micro-LEDs arranged on the substrate, and is characterized in that a red light perovskite Micro-LED is arranged 0.1 to 100 μm away from the blue and green light Micro-LEDs.

[0008] Preferably, the perovskite material used in the red light perovskite Micro-LED is A2B N-1 M N X 3N+1 or BMX3, wherein A is a long-chain organic cation, B is a monovalent cation, M is a divalent metal cation, X is any one or more of the halogen elements Cl, Br, I, N (N = 1, 2, ..., ∞) is the number of layers of the inorganic skeleton of the perovskite material, and the perovskite material is preferably A2B N-1 M N X 3N+1 , N = 1, 2, ... 50;

[0009] Or the perovskite material is one or more of the perovskite derivatives Cs4SnBr6, Cs4SnI6, Cs4SnCl6, Cs3Bi2I9, Cs3Sb2I9, Cs3Sb2Br9, Cs3Sb2Cl9, Cs5Cu3Cl6I2, Cs5Cu3Cl7I, CsCu2Cl3, CsCu2I3, CsCu2Br3, Ru2CuBr3, Ru2CuCl3, K2CuBr3, CsCu2I2Cl, CsCu2I2Br, CsCu2Br2I, CsCu2Br2Cl, CsCu2Cl2I, CsCu2Cl2Br, and Cs3Bi2Br9.

[0010] Most preferably, the perovskite material used in the red light perovskite Micro-LED is BM(I x Br 1-x )3, wherein B is one or more of Cs, FA, Rb, GA, M is one or more of Pb, Sn, and 0≤x≤1.

[0011] Preferably, the red light perovskite Micro-LED is 0.1 to 5 μm away from the blue and green light Micro-LEDs, more preferably 0.1 to 3 μm away from the blue and green light Micro-LEDs, and most preferably 0.1 to 1 μm away from the blue and green light Micro-LEDs. If the red light perovskite Micro-LED is too far away from the blue and green light LEDs, it is not conducive to achieving high-resolution display.

[0012] Preferably, when the substrate is a transparent substrate, the blue and green light Micro-LEDs are in a front-mounted structure, and the blue, green and red light Micro-LEDs are bottom-emitting devices; when the substrate is a non-transparent substrate, the blue and green light Micro-LEDs are in a flip-chip structure, and the blue, green and red light Micro-LEDs are top-emitting devices.

[0013] Preferably, the blue and green light Micro-LEDs are prepared on the substrate by transfer or directly, and the direct preparation method of the blue and green light Micro-LEDs includes thin film growth methods such as epitaxial growth, evaporation, spin coating, and ALD.

[0014] Preferably, the red light perovskite Micro-LED includes a functional layer and an electrode, and the functional layer includes a red light Micro-LED electron transport layer, a red light Micro-LED active layer and a red light Micro-LED hole transport layer.

[0015] Preferably, the preparation of the red light Micro-LED electron transport layer comprises the following steps:

[0016] Spin-coat ZnO or SnO2 onto the red light Micro-LED bottom electrode array and bake it on a hot plate;

[0017] Alternatively, ZnO or SnO2 is deposited onto the red light Micro-LED bottom electrode array by ALD through a mask.

[0018] Preferably, the preparation of the red light Micro-LED active layer comprises the following steps:

[0019] The perovskite precursor solution is dropped onto the red light Micro-LED electron transport layer and spin-coated at a speed of 1000-8000 rpm, and annealed at 40-200 °C;

[0020] Or at a vacuum degree of 4×10 -3 ~1×10 -6 Under Pa, a perovskite precursor solution with a thickness of 10-300nm is deposited onto the red light Micro-LED electron transport layer through a mask plate by a multi-source co-evaporation method to obtain a red light Micro-LED active layer.

[0021] Preferably, the perovskite precursor solution is prepared by dissolving AX, BX and MX in a solvent at a molar ratio of 1-100:1-100:1-100, with a mass fraction of 1%-50%; preferably, the molar ratio of AX, BX and MX is 1-10:1-10:1-10, with a mass fraction of 5%-25%. The preferred solvent is N,N-dimethylformamide and dimethyl sulfoxide.

[0022] In the present invention, the addition of an additive with a molar concentration of 0.005 to 0.5 mol / L to the perovskite precursor solution can promote the formation of the perovskite luminescent phase and obtain a flat and dense perovskite film. Preferably, the additive is a metal salt additive with a molar concentration of 0.05 to 0.2 mol / L; or an organic additive with a molar concentration of 0.005 to 0.1 mol / L. The metal salt additive is composed of a metal salt having a molar concentration of 0.05 to 0.2 mol / L and a metal salt having a molar concentration of 0.005 to 0.1 mol / L. + or M 2+ It is composed of metal cations with similar ionic radius or the same valence and acid anions with different functional groups. The metal cation is Na + , K + , Li + , Mn 2+ Mg 2+ , Ca 2+ , Ba 2+ 、Zn 2+ , the acid anion is PO3 2- 、HPO4 2- 、CO3 2- 、SO4 2- 、NO3 - HCOO - 、CH3COO - 、SCN - , CN - ; The organic additive has a functional group that interacts with the perovskite component, including one or more of -NH2, -OH, -COOH, -CN, -NC, -SH, -PH2, -SCN, -CHO, -SO3H, -CH(O)CH. The most preferred metal salt additive is one or more of Zn(CH3COO)2 or CH3COONa; the organic additive is one or more of betaine, amino acid, 1-aminopyridine iodide, and aminoethanesulfonic acid.

[0023] Preferably, the preparation of the red light Micro-LED hole transport layer comprises the following steps: spin coating TFB, TPD, PTAA or PVK solution on the red light Micro-LED active layer at a rotation speed of 1000-8000 rpm;

[0024] Alternatively, TAPC or TCTA is evaporated onto the red light Micro-LED active layer through a mask plate;

[0025] Alternatively, a red light Micro-LED hole transport layer is prepared on the bottom electrode array, and the preparation includes the following steps: spin coating PEDOT:PSS, PVK, PTAA, TPD or TFB on the red light Micro-LED bottom electrode array at a rotation speed of 1000-8000rpm, and baking on a hot stage.

[0026] Alternatively, the red light Micro-LED electron transport layer is prepared on the active layer, and its preparation includes the following steps: evaporating or spin coating the TPBi or TmPyPB electron transport layer on the red light Micro-LED active layer.

[0027] The method for preparing the full-color Micro-LED chip array based on red light perovskite material comprises the following steps:

[0028] S1. Realize blue and green light Micro-LED arrays by transfer or direct preparation on substrate;

[0029] S2. Prepare red light perovskite Micro-LEDs at 0.1 to 100 μm next to the arrayed blue and green Micro-LEDs.

[0030] LED required pattern;

[0031] S3. Prepare the functional layers of red light Micro-LED in sequence on the exposed red light perovskite Micro-LED pattern.

[0032] In the above array S1, blue and green Micro-LED pads have been reserved; the chips are fixed by precise transfer and electrical interconnection is achieved through bonding.

[0033] The red light Micro-LED electrode can be prepared before the blue light and green light Micro-LED are transferred, or after the blue light and green light Micro-LED are bonded.

[0034] The pattern required for realizing the red light perovskite Micro-LED can be achieved by photolithography, electron beam etching, transfer, inkjet printing and the like.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] (1) The present invention successfully integrates red light perovskite LEDs with blue and green light Micro-LEDs of the III-V group, which can effectively meet the requirements for higher efficiency, brightness and color purity in Micro-LED applications.

[0037] (2) The perovskite red light array in the Micro-LED array is directly prepared on the chip and does not require transfer, which greatly reduces the cost of Micro-LED preparation.

[0038] (3) The prepared perovskite red light Micro-LED has good high current resistance characteristics, and its efficiency is still at the same level as that of a large area when the scale is 20μm. It does not have the serious efficiency drop phenomenon of traditional InGaN-based red light materials when the size is reduced.

[0039] Therefore, the full-color Micro-LED chip array based on red light perovskite material of the present invention has the advantages of lower preparation cost, higher color purity, no obvious sidewall effect, and higher efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Transparent circuit board prepared in Example 1 of the present invention

[0041] Figure 2 The blue and green light Micro-LED chips epitaxially grown on the sapphire substrate in Example 1 of the present invention

[0042] Figure 3 This is the etching diagram of the blue and green Micro-LEDICP mesa in Example 1 of the present invention

[0043] Figure 4 The structure diagram of the transparent electrodes and chip pads of blue and green Micro-LEDs prepared in Example 1 of the present invention

[0044] Figure 5 This is a blue and green Micro-LED substrate and epitaxial growth buffer layer peeling structure diagram of Example 1 of the present invention

[0045] Figure 6 This is a diagram of the cutting structure of blue and green Micro-LEDs in Example 1 of the present invention

[0046] Figure 7 This is a diagram of the blue and green Micro-LED transfer and COB wire bonding structure of Example 1 of the present invention

[0047] Figure 8 Schematic diagram of blue and green Micro-LED packaging and photolithography to obtain a transparent electrode pattern for red Micro-LED in Example 1 of the present invention

[0048] Fig. 9 This is the structure diagram of the preparation of the perovskite red light Micro-LED in Example 1 of the present invention

[0049] Fig.10 This is a SEM image of the perovskite red light Micro-LED active layer film in Example 1 of the present invention

[0050] Fig.11 The normalized spectrum of the perovskite red light Micro-LED with a lateral size of 20 μm at 4V in Example 1 of the present invention

[0051] Fig.12 J-EQE curve of the perovskite red light Micro-LED in Example 1 of the present invention with a lateral size of 20 μm

[0052] Fig.13JV curve and LV curve of the perovskite red light Micro-LED in Example 1 of the present invention with a lateral size of 20 μm

[0053] Fig.14 Circuit board prepared in Example 2 of the present invention

[0054] Fig.15 Schematic diagram of pre-setting blue and green Micro-LED solder balls on a circuit board in Example 2 of the present invention

[0055] Fig.16 The structure diagram of the blue and green light Micro-LED chips epitaxially grown on a sapphire substrate in Example 2 of the present invention Fig.17 This is the ICP table etching structure diagram of the blue and green Micro-LED in Example 2 of the present invention

[0056] Fig.18 The structure diagram of the blue and green Micro-LED pads prepared in Example 2 of the present invention

[0057] Fig.19 This is a diagram of the blue and green flip-chip Micro-LED transfer, reflow soldering and substrate peeling structure of Example 2 of the present invention

[0058] Fig. 20 This is a diagram of the blue and green flip-chip Micro-LED packaging structure of Example 2 of the present invention

[0059] Fig.21 This is a structural diagram of the preparation of the red light Micro-LED full reflection bottom electrode array pattern in Example 2 of the present invention

[0060] Fig. 22 Preparation of a perovskite red light Micro-LED full reflection electrode by magnetron sputtering method in Example 2 of the present invention

[0061] Fig.23 This is a diagram of the thin film structure of each layer of the evaporation method perovskite red light Micro-LED in Example 2 of the present invention

[0062] Fig.24 This is the structure diagram of the perovskite red light Micro-LED package in Example 2 of the present invention

[0063] Fig.25 This is a SEM image of the perovskite red light Micro-LED active layer film in Example 2 of the present invention

[0064] Fig.26 The J-EQE curve of the perovskite red light Micro-LED in Example 2 of the present invention with a lateral size of 20 μm

[0065] Fig. 27JV curve and LV curve of the red light Micro-LED in Example 2 of the present invention with a lateral size of 20 μm

[0066] Fig.28 The normalized spectrum of the perovskite red light Micro-LED with a lateral size of 20 μm at 4V in Example 2 of the present invention

[0067] Fig.29 This is a structural diagram of the preparation of the perovskite red light Micro-LED in Example 3 of the present invention

[0068] Fig.30 JV curve and LV curve of the red light Micro-LED in Example 3 of the present invention with a lateral size of 20 μm

[0069] Fig.31 The J-EQE curve of the perovskite red light Micro-LED in Example 3 of the present invention with a lateral size of 20 μm

[0070] Fig.32 The normalized spectrum of the perovskite red light Micro-LED with a lateral size of 20 μm at 4V in Example 3 of the present invention

[0071] Fig.33 J-EQE curve of the red light Micro-LED in comparative example 1 of the present invention with a lateral size of 20 μm DETAILED DESCRIPTION

[0072] The present invention is further explained below by specific examples:

[0073] Example 1: Preparation of blue and green light front-mounted Micro-LEDs and bottom-emitting transverse red light Micro-LED arrays by solution method.

[0074] like Figure 1-9In the figure, 1 is a transparent circuit board; 2 and 4 are cathode pads of blue and green Micro-LEDs on the transparent circuit board respectively; 3 and 5 are anode pads of blue and green Micro-LEDs on the transparent circuit board respectively; 6 is a sapphire substrate; 7 is a U-GaN buffer layer; 8 is N-GaN; 9 is a blue and green Micro-LED active layer (MQW); 10 is P-GaN; 11 is a transparent conductive glass (ITO), anode pad of the chip; 12 is a cathode metal pad of the chip; 13 is a blue Micro-LED horizontal structure chip; 14 is a green Micro-LED horizontal structure chip; 15 is a cured SU8; 16 is a red Micro-LED transparent bottom electrode ITO; 17 is a red Micro-LED electron transport layer; 18 is a red Micro-LED active layer; 19 is a red Micro-LED hole transport layer; 20 is a red Micro-LED shared metal electrode MoO x / Au.

[0075] Step 1, preparation of red light Micro-LED bottom electrode array: clean the surface of the transparent substrate, deposit ITO by magnetron sputtering, and obtain the red light Micro-LED bottom electrode array by wet etching or dry etching;

[0076] Step 2, preparation of cathode and anode pads for blue and green Micro-LEDs: spin coating photoresist (BP212), developing after exposure to expose the arrayed patterns of cathode and anode pads for blue and green Micro-LEDs, evaporating and depositing metal electrodes, and finally obtaining arrayed cathode and anode pads by photoresist stripping, such as Figure 1 As shown;

[0077] Step 3, preparation of blue and green Micro-LED horizontal chips: obtain U-GaN with a thickness of 1μm, N-GaN with a thickness of 1μm, MQW with a thickness of 5-15nm, and P-GaN with a thickness of 300nm in sequence, and then obtain ITO with a thickness of 100-200nm by magnetron sputtering; expose the N-GaN layer by ICP etching, and improve the ohmic contact of ITO and P-GaN by thermal annealing in a nitrogen atmosphere, and finally deposit ITO and N-GaN on the cathode and anode metal electrodes respectively, and finally form an ohmic contact by thermal annealing, such as Figure 5 As shown;

[0078] Step 4, chip miniaturization and transfer: blue and green Micro-LEDs are obtained by laser cutting, and the blue and green Micro-LEDs are transferred to a transparent substrate through mass transfer technology, and the chips are fixed by transparent adhesive;

[0079] Step 5, sapphire substrate peeling and wire bonding: peel off the sapphire substrate, and weld the metal pads reserved on the chip and the prepared metal pads on the transparent circuit board through COB wire bonding to achieve electrical interconnection, such as Figure 7 As shown;

[0080] Step 6, blue and green Micro-LED packaging: Based on step 5, spin coating is performed at a speed of 4000 rpm and an acceleration of 1000 rpm for 45 seconds to obtain an SU8 film, which is then exposed under a photomask. After development, the ITO transparent electrode arrayed with red Micro-LEDs is exposed. The ITO transparent electrode is 0.5 μm away from the blue-green Micro-LED device. Finally, the film is heated and cured at 150°C. The SU8 remaining in the blue and green Micro-LEDs can isolate the influence of subsequent red light preparation on the blue and green light.

[0081] Step 7, preparation of red light Micro-LED electron transport layer: take 30 microliters of SnO2 aqueous solution with a concentration of 10-20wt% and spin-coat it on the red light Micro-LED bottom electrode array at a speed of 4000 rpm and an acceleration of 4000 rpm for 45 seconds, and bake it on a hot plate at 150°C for 10 minutes;

[0082] Step 8, preparation of red light Micro-LED active layer: 30 μl of CsI, PbI2, PbBr2 and Zn(Ac)2 additives were dissolved in solvent N,N-dimethylformamide at a molar ratio of 1.5:0.8:0.2:1.5, and the mass fraction was 10% to prepare CsPb(I 0.8 Br 0.2 The solution of )3 was dropped onto the red light Micro-LED electron transport layer at a speed of 4000 rpm and an acceleration of 4000 rpm for 45 s, and then annealed at 120 ° C for 10 min;

[0083] Step 9, preparation of the hole transport layer of the red light Micro-LED: take 30 μl of the prepared 10 mg / ml TFB solution and spin coat it on the red light Micro-LED active layer at a speed of 2000 rpm and an acceleration of 4000 rpm for 45 seconds;

[0084] Step 10, preparation of the third functional layer and metal electrode, based on the above, the sample is transferred to a thermal evaporation device at a chamber pressure of 4×10 -4 4.5nm MoO was deposited successively under Pa conditions x with 70nm Au.

[0085] Thin film and device characterization:

[0086] The film and red light Micro-LED device prepared in Example 1 were characterized, and the results obtained were as follows: Fig.10 ,11 , 12, 13. Fig.10 It can be seen that the solution method has obtained a dense and uniform red light Micro-LED active layer with a grain size of about 20nm. Fig.11 It can be seen that the red light Micro-LED device has a central wavelength of 688nm, and can still maintain an EQE of 12.2% when the lateral size is 20μm (e.g. Fig.12 shown).

[0087] Example 2: Preparation of Blue and Green Light Inverted Micro-LED and Top-Emitting Red Micro-LED Array by Evaporation Method

[0088] like Figure 14-24 In the figure, 21 is a circuit board; 22 and 24 are cathode pads of blue and green Micro-LEDs; 23 and 25 are anode pads of blue and green Micro-LEDs; 26 is a solder ball; 27 is a sapphire substrate; 28 is a U-GaN buffer layer; 29 is N-GaN; 30 is an active layer (MQW) of blue and green Micro-LEDs; 31 is P-GaN; 32 is anode metal pad of the chip; 33 is transparent conductive glass (ITO) and cathode metal pad of the chip; 34 is a flip-chip structure chip of blue Micro-LED; 35 is a flip-chip structure chip of green Micro-LED; 36 is a cured SU8; 37 is a fully reflective bottom electrode of red Micro-LED; 38 is an electron transport layer of red Micro-LED; 39 is an active layer of red Micro-LED; 40 is a top electrode of red Micro-LED; 41 is a packaged red Micro-LED.

[0089] Step 1, preparation of cathode and anode pads for blue and green Micro-LEDs: spin-coat a photoresist (BP212) with a thickness of 500nm, expose and develop the arrayed patterns of cathode and anode pads for blue and green Micro-LEDs, deposit metal electrodes by evaporation, and finally obtain the arrayed cathode and anode pads by stripping the photoresist, such as Fig.14 As shown;

[0090] Step 2, blue and green Micro-LED flip chip preparation: Fig.16 As shown, the blue and green Micro-LEDs are obtained by epitaxial method to obtain 1μm U-GaN, 1μm N-GaN, 5-15nm MQW, 300nm P-GaN, and then 100-200nm ITO is obtained by magnetron sputtering; the N-GaN layer is exposed by ICP dry etching, and the ohmic contact of ITO and P-GaN is improved by thermal annealing, and the cathode and anode metals are deposited on ITO and N-GaN respectively, and finally the ohmic contact is formed by thermal annealing;

[0091] Step 3, chip miniaturization, transfer and flip-chip soldering: laser cutting to obtain blue and green Micro-LEDs; pre-plant solder balls on the cathode and anode pads on the substrate; flip-chip transfer and align the blue and green Micro-LEDs and perform reflow soldering, such as Fig.19 As shown;

[0092] Step 4, sapphire substrate stripping and blue and green chip packaging: the sapphire substrate is stripped; the SU8 film is obtained by spin coating at a speed of 4000 rpm and an acceleration of 1000 rpm for 45 seconds, and exposed under a photomask. After development, the red light Micro-LED array pattern is exposed, and the position is 2.5 μm away from the blue and green light Micro-LED. The remaining SU8 can realize the effect of blue and green light Micro-LED packaging and isolation of red light Micro-LED preparation, and finally heat and cure at 150 ° C;

[0093] Step 5: Preparation of red light Micro-LED full reflection bottom electrode: In a vacuum of 4×10 -4 Pa, metal is deposited onto the exposed Micro-LED array pattern by physical vapor deposition under the mask, such as Fig. 22 As shown;

[0094] Step 6, preparation of red light Micro-LED electron transport layer: through a reticle mask, SnO2 with a thickness of 30nm is deposited on the arrayed total reflection bottom electrode by ALD;

[0095] Step 7, preparation of red light Micro-LED active layer: in a vacuum of 4×10 -4 Pa, through the mask, a 30nm thick layer was prepared by ternary co-evaporation of CsI, PbI2 and PbBr2 in a molar ratio of 1.5:0.8:0.2 to obtain CsPb(I 0.8 Br 0.2 )3 is deposited onto the arrayed SnO2, and then an active layer is obtained by annealing at 120°C for 4 min in an N,N-dimethylformamide solvent atmosphere;

[0096] Step 8, preparation of red LED hole transport layer: similar to step 7, 60nm TFB is deposited on the Micro-LED active layer pattern;

[0097] Step 9, preparation of top metal electrode: Similar to step 7, 4.5nm MoO x , 15nm Au was deposited onto the arrayed TFBs.

[0098] Thin film and device characterization:

[0099] The thin film and device prepared in Example 2 were characterized, and the results obtained were as follows Fig.25 , 26 , 27, 28. Fig.25 It can be seen that the evaporation method has obtained a dense and uniform red light Micro-LED active layer with a grain size of about 20nm. Fig.26 It can be seen that the red light Micro-LED device has a central wavelength of 688nm, and can still maintain an EQE of 11.7% when the lateral size is 20μm (e.g. Fig. 27 ).

[0100] Example 3: Preparation of blue and green light front-mounted Micro-LEDs and bottom-emitting red light Micro-LED arrays by solution method.

[0101] like Figure 1-9 In the figure, 1 is a transparent circuit board; 2 and 4 are cathode pads of blue and green Micro-LEDs on the transparent circuit board respectively; 3 and 5 are anode pads of blue and green Micro-LEDs on the transparent circuit board respectively; 6 is a sapphire substrate; 7 is a U-GaN buffer layer; 8 is N-GaN; 9 is a blue and green Micro-LED active layer (MQW); 10 is P-GaN; 11 is a transparent conductive glass (ITO), anode pad of the chip; 12 is a cathode metal pad of the chip; 13 is a blue Micro-LED horizontal structure chip; 14 is a green Micro-LED horizontal structure chip; 15 is a cured SU8; 16 is a transparent bottom electrode ITO of a red Micro-LED; as shown in FIG. Fig.29 , 42 is the red light Micro-LED hole transport layer; 43 is the red light Micro-LED active layer; 44 is the red light Micro-LED electron transport layer; 45 is the red light Micro-LED shared metal electrode LiF / Al.

[0102] Step 1 to step 6 are the same as in Example 1.

[0103] Step 7, preparation of hole transport layer of red light Micro-LED: 30 μl of 10-20 wt% PEDOT:PSS aqueous solution, 1-20 mg / ml PVK, 1-20 mg / ml PTAA or 1-10 mg / ml TFB solution are spin-coated on the bottom electrode array of red light Micro-LED at 4000 rpm and 4000 rpm acceleration for 45 seconds, and baked on a hot plate at 100 ° C for 10 minutes;

[0104] Step 8, preparation of red light Micro-LED active layer: Take 30 μl of PEAI, CsI, CsBr, PbI2, PbBr2 and thiobetaine additive in a molar ratio of 0.2:1.3:0.1:0.8:0.2:0.1 and dissolve in solvent N,N-dimethylformamide to obtain APb(I 0.8 Br 0.2 )3 solution was dropped onto the red light Micro-LED electron transport layer at a speed of 4000 rpm and an acceleration of 4000 rpm for 45 s, and annealed at 120 ° C for 10 min;

[0105] Step 9, preparation of red light Micro-LED electron transport layer: evaporation of 30nm TPBi electron transport layer on the red light Micro-LED active layer;

[0106] Step 10, preparation of the third functional layer and metal electrode, based on the above, the sample is transferred to a thermal evaporation device at a chamber pressure of 4×10 -4 3nm LiF and 70nm Al were deposited sequentially under Pa conditions.

[0107] Device Characterization:

[0108] The device prepared in Example 3 was characterized, and the results obtained were as follows Fig.30 , 31 , 32. The red light Micro-LED device has a central wavelength of 688nm (as shown in FIG. Fig.32 ), and can still maintain 10.44% EQE when the lateral size is 20μm (such as Fig.31 ).

[0109] Comparative Example 1

[0110] Comparing the performance of a 20μm red AlGaInP-based Micro-LED integrated on the same blue-green Micro-LED, the device was fabricated on a commercial four-inch AlGaInP wafer grown using metal organic chemical vapor deposition on a GaAs substrate, and after cleaning with organic solvents (ethanol, acetone), 110nm indium tin oxide (ITO) was deposited by electron beam evaporation as an ohmic and transparent p-type contact. The ITO layer was removed using reactive ion etching, and the AlGaInP material was etched at 200°C using chlorine-based inductively coupled plasma etching. All devices were made into circular shapes with a diameter range of 20μm. An omnidirectional reflector (ODR) consisting of five pairs of alternating layers of silicon dioxide and tantalum pentoxide was deposited using ion beam deposition. The ODR thickness produced a measured reflectivity of 85% in the range of 630-650nm to minimize light absorption and served as a metal isolation dielectric layer. Electron beam evaporation was used to prepare metal consisting of 12 / 80 / 10 / 500nm Ge / Au / Ni / Au for common p-type and n-type metal contacts. The metal contacts were annealed at 430°C for 60 seconds under nitrogen to obtain n-type ohmic contacts. Red light Micro-LEDs were obtained by laser cutting and transferred to blue-green light Micro-LED substrates by mass transfer technology.

[0111] A 20μm perovskite red light Micro-LED was prepared on a substrate integrated with the same blue-green light Micro-LED. The SU8 film was obtained by spin coating at a speed of 4000rpm and an acceleration of 1000rpm for 45s. After exposure and development, the ITO transparent electrode with red light Micro-LED array was exposed. The ITO was made into a circle with a diameter range of 20μm, and finally heated and cured at 150°C. Take 30 microliters of SnO2 aqueous solution with a concentration of 10-20wt% and spin-coat it on the ITO substrate at a speed of 4000rpm and an acceleration of 4000rpm for 45s, and bake it on a hot plate at 150°C for 10min to obtain a 30nm electron transport layer; take 30 microliters of CsI, PbI2, PbBr2 and Zn(CH3COO)2 additives prepared with a molar ratio of 1.5:0.8:0.2:1.5 dissolved in the solvent N,N-dimethylformamide, and the mass fraction was 10% to obtain CsPb(I 0.8 Br 0.2)3 solution was dripped onto the red light Micro-LED electron transport layer at a speed of 4000 rpm and an acceleration of 4000 rpm for 45 seconds, and annealed at 120 ° C for 10 minutes to obtain a red light perovskite active layer; then 30 microliters of the prepared 10 mg / ml TFB solution was taken and spin-coated on the red light Micro-LED active layer at a speed of 2000 rpm and an acceleration of 4000 rpm for 45 seconds to obtain a hole transport layer; on the basis of the above, the sample was transferred to a thermal evaporation device and 4.5 nm MoO x with 70nm Au.

[0112] The performance of devices made of perovskite materials is significantly better than that of traditional III-IV red light Micro-LEDs, with an external quantum efficiency of >10%, which is about 10 times the efficiency of III-IV red light Micro-LEDs (such as Fig.33 ).

Claims

1. A full-color Micro-LED chip array based on red light perovskite material, the array comprising a plurality of Micro-LED chips, each of which comprises a substrate and blue and green light Micro-LEDs arranged on the substrate, characterized in that: A red light perovskite Micro-LED is arranged 0.1 to 100 μm away from the blue and green light Micro-LEDs.

2. The full-color Micro-LED chip array based on red light perovskite material according to claim 1, characterized in that: The perovskite material used in the red light perovskite Micro-LED is A2B N-1 M N X 3N+1 or BMX3, wherein A is a long-chain organic cation, B is a monovalent cation, M is a divalent metal cation, X is any one or more of the halogen elements Cl, Br, I, N is 1, 2, ..., ∞, is the number of layers of the inorganic skeleton of the perovskite material, or is a perovskite derivative Cs4SnBr6, Cs4SnI6, Cs4SnCl6, Cs3Bi2I9, Cs3Sb2I9, Cs3Sb2Br9, Cs3Sb2C l9, one or more of Cs5Cu3Cl6I2, Cs5Cu3Cl7I, CsCu2Cl3, CsCu2I3, CsCu2Br3, Ru2CuBr3, Ru2CuCl3, K2CuBr3, CsCu2I2Cl, CsCu2I2Br, CsCu2Br2I, CsCu2Br2Cl, CsCu2Cl2I, CsCu2Cl2Br, and Cs3Bi2Br9.

3. The full-color Micro-LED chip array based on red light perovskite material according to claim 1, characterized in that: When the substrate is a transparent substrate, the blue and green light Micro-LEDs are in a front-mounted structure, and the blue, green and red light Micro-LEDs are bottom-emitting devices; when the substrate is a non-transparent substrate, the blue and green light Micro-LEDs are in a flip-chip structure, and the blue, green and red light Micro-LEDs are top-emitting devices.

4. The full-color Micro-LED chip array based on red light perovskite material according to claim 1, characterized in that: The red light perovskite Micro-LED includes a functional layer and an electrode, and the functional layer includes a red light Micro-LED electron transport layer, a red light Micro-LED active layer and a red light Micro-LED hole transport layer.

5. The full-color Micro-LED chip array based on red light perovskite material according to claim 4, characterized in that: The preparation of the red light Micro-LED electron transport layer comprises the following steps: Spin-coat ZnO or SnO2 onto the red light Micro-LED bottom electrode array and bake it on a hot plate; Alternatively, ZnO or SnO2 is deposited onto the red light Micro-LED bottom electrode array by ALD through a mask.

6. The full-color Micro-LED chip array based on red light perovskite material according to claim 4, characterized in that: The preparation of the red light Micro-LED active layer comprises the following steps: The perovskite precursor solution is dropped onto the red light Micro-LED electron transport layer and spin-coated at a speed of 1000-8000 rpm, and annealed at 40-200 °C; Or at a vacuum degree of 4×10 -3 ~1×10 -6 Under Pa, a perovskite precursor solution with a thickness of 10-300nm is deposited onto the red light Micro-LED electron transport layer through a mask plate by a multi-source co-evaporation method to obtain a red light Micro-LED active layer.

7. The full-color Micro-LED chip array based on red light perovskite material according to claim 6, characterized in that: The perovskite precursor solution is prepared by dissolving AX, BX and MX in a solvent at a molar ratio of 1-100:1-100:1-100, with a mass fraction of 1%-50%; preferably, the molar ratio of AX, BX and MX is 1-10:1-10:1-10, with a mass fraction of 5%-25%.

8. The full-color Micro-LED chip array based on red light perovskite material according to claim 4, characterized in that: The preparation of the red light Micro-LED hole transport layer comprises the following steps: spin coating TFB, TPD, PTAA or PVK solution on the red light Micro-LED active layer at a rotation speed of 1000-8000 rpm; Alternatively, TAPC or TCTA is evaporated onto the red light Micro-LED active layer through a mask plate; Alternatively, a red light Micro-LED hole transport layer is prepared on the bottom electrode array, specifically, PEDOT:PSS, PVK, PTAA, TPD or TFB is spin-coated on the red light Micro-LED bottom electrode array at a rotation speed of 1000-8000 rpm, and baked on a hot plate; Alternatively, the red light Micro-LED electron transport layer is prepared on the active layer, specifically: TPBi or TmPyPB electron transport layer is evaporated or spin-coated on the red light Micro-LED active layer.

9. A method for preparing a full-color Micro-LED chip array based on red light perovskite material according to claim 1, characterized in that The method comprises the following steps: S1. Realize blue and green light Micro-LED arrays by transfer or direct preparation on substrate; S2, prepare the pattern required for realizing red light perovskite Micro-LED at 0.1-100 μm next to the arrayed blue and green Micro-LED; S3. Prepare the functional layers of red light Micro-LED in sequence on the exposed red light perovskite Micro-LED pattern.

10. The method for preparing a full-color Micro-LED chip array based on red light perovskite material according to claim 9, characterized in that: In the S1 step, blue and green Micro-LED pads are reserved, the chips are fixed by precise transfer, and electrical interconnection is achieved by wire bonding.

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