Inorganic Perovskite Quantum Dots Research Articles

Progress on perovskite quantum dots and light-emitting diodes

Abstract. Perovskite quantum dots have become a popular material for the development of new high-efficiency light-emitting diodes (LED) because of their high photoluminescence quantum yield, adjustable luminescence spectrum, narrow spectral width, high defect tolerance and unique quantum limit effect. We review the recent progress based on LED of different types of perovskite quantum dots. First, the properties, existing problems and applications of fully inorganic perovskite quantum dots are introduced. Subsequently, both organic and inorganic perovskites and their applications are discussed, and several methods to improve the LED efficiency of perovskite quantum dots are explored. Finally, this paper analyzes the current challenges of LED of perovskite quantum dots, such as instability and toxicity, and its application prospect in the field of high-efficiency display and lighting is discussed. That is, the EQE of LED based on perovskite quantum dots has increased to more than 20% in four years, and the service life has been extended to tens of hours. This review provides useful insights for the development of more efficient and safer perovskite quantum dot luminescence devices.

CsPbBr3 perovskite quantum dots by mesoporous silica encapsulated for enhancing water and thermal stability via high temperature solid state method

All inorganic perovskite quantum dots (PQDs) have great application prospects in the lighting and display fields due to their excellent photoelectric properties. However, their instabilities in water and high temperature lead to photoluminescence (PL) quenching, and colloidal synthesis methods usually use a mass of organic solvents, limiting their practical application. Herein, we successfully synthesized mesoporous silica (m-SiO2) and employed a confinement effect to successfully synthesize CsPbBr3@m-SiO2 powders using a simple high-temperature solid-phase synthesis method in an air atmosphere. When the m-SiO2 content is 0.2 g, optimal green luminous intensity is achieved with a peak wavelength of 522 nm and a full width at half maximum (FWHM) of 23 nm. CsPbBr3@m-SiO2 powders have excellent thermal stability, the PL spectral shapes do not change and the PL intensity can maintain 88.1 % of the original level after 10 heating cycles (200 °C). In addition, CsPbBr3@m-SiO2 powders exhibit excellent water stability, which can still be well dispersed after 30 days exposure to water, and the PL strength remain basically unchanged. This study presents a novel approach for the advancement of stable perovskite luminescent materials.

Ligand Engineering of Inorganic Lead Halide Perovskite Quantum Dots toward High and Stable Photoluminescence.

The ligand engineering of inorganic lead halide perovskite quantum dots (PQDs) is an indispensable strategy to boost their photoluminescence stability, which is pivotal for optoelectronics applications. CsPbX3 (X = Cl, Br, I) PQDs exhibit exceptional optical properties, including high color purity and tunable bandgaps. Despite their promising characteristics, environmental sensitivity poses a challenge to their stability. This article reviews the solution-based synthesis methods with ligand engineering. It introduces the impact of factors like humidity, temperature, and light exposure on PQD's instability, as well as in situ and post-synthesis ligand engineering strategies. The use of various ligands, including X- and L-type ligands, is reviewed for their effectiveness in enhancing stability and luminescence performance. Finally, the significant potential of ligand engineering for the broader application of PQDs in optoelectronic devices is also discussed.

Sensitive detection of bilirubin using highly luminescent benzylamine capped CH3NH3PbBr3 perovskite quantum dots

Luminescent organic–inorganic metal halide hybrid perovskite quantum dots (PQDs) as a new class of fluorophores are finding increasing attention towards chemical and biological sensing due to their exceptional photophysical properties. Herein, we synthesized highly fluorescent CH3NH3PbBr3 perovskite quantum dots (B-PQDs) through the ligand assisted reprecipitation method (LARP), using benzylamine as the surface capping ligand. Morphological and opto-structural properties of the as-synthesized B-PQDs were thoroughly investigated using high resolution transmission electron microscopy (HR-TEM), X-Ray diffraction (XRD), Fourier transform infra-red spectroscopy (FT-IR), UV–Vis absorption, and fluorescence spectroscopy. The as-synthesized electron-rich amine-capped B-PQDs were employed to study their sensing response towards bilirubin (BL). The aromatic amine capped B-PQDs enhance the sensory response towards BL due to the π-π interaction with BL’s conjugated system. The B-PQDs were found to be highly sensitive towards BL with a stern–volmer constant value ≈ 4.3 × 104 M−1 and limit of detection of 0.42 μM. A panel of characterizations were carried out to investigate the detailed sensing mechanism where resonance energy transfer was found to be the dominant quenching mechanism for BL detection. Our results demonstrated the potential for utilizing organic–inorganic halide perovskite quantum dots for sensing applications, through surface ligand modification tailored for detecting specific analytes.

Preparation of F/Mn-doped CsPb(Br/Cl)3 quantum-dot glass and their luminescence properties

All inorganic lead halide cesium perovskite quantum dots (QDs) have attracted much attention due to their excellent luminescence properties, but further development is restricted by their stability and the existence of toxic element lead. In this paper, F/Mn-doped [Formula: see text] QDs glass was prepared by melt quenching and heat treatment, with reduced Pb content effectively. The result shows that the spectrum of the QD glass is adjustable between 450 nm and 515.4 nm by changing the feeding ratio of Mn-Pb ion and heat treatment temperature. Moreover, the indraught of [Formula: see text] effectively improves the PLQY of [Formula: see text] QDs glass and serves as a red-emitting. The prepared composites not only maintain good fluorescence characteristics, but also greatly improve the stability of QDs. And successfully coupled with blue LED chips to synthesize WLED, Under 20 mA current, the color coordinate is (0.3446, 0.3389).

Passivation of 2D Cs2PbI2Cl2 Nanosheets for Efficient and Stable CsPbI3 Quantum Dot Solar Cells.

Inorganic CsPbI3 perovskite quantum dots (PQDs) possess remarkable optical properties, making them highly promising for photovoltaic applications. However, the inadequate stability resulting from internal structural instability and the complex external surface chemical environment of CsPbI3 PQDs has hindered the development of CsPbI3 PQD solar cells (PQDSCs). In this work, the capping layer composed of inorganic two-dimensional (2D) Ruddlesden-Popper (RP) phase Cs2PbI2Cl2 nanosheets (NSs) is introduced, which may be effectively treated to improve the surface properties of the CsPbI3 PQD film. This modification serves to passivate defects by filling cesium and iodine vacancies while optimizing the energy band arrangement and preventing humidity intrusion, leading to the meliorative stability and photovoltaic performance. The optimized CsPbI3 PQDSCs achieve an enhanced power conversion efficiency (PCE) of 14.73%, with the superb stability of only a 16% efficiency loss after being exposed to ambient conditions (30 ± 5% RH) for 432 h.

Mn-doped perovskite quantum dots with thermal stability synthesized at room temperature

All inorganic perovskite quantum dots (PQDs) have been studied extensively because of their excellent photoelectric properties. However, its poor stability and lead toxicity limit its practical application. At the same time, the complex synthesis conditions of the hot injection method also limited the preparation of large quantities. Here, we have successfully synthesized Mn-doped CsPb(Cl/Br)3 PQDs with excellent thermal stability at room temperature by a simple supersaturation crystallization method. The synthesized Mn-doped CsPb(Cl/Br)3 PQDs has good homogeneity and crystallinity. Meanwhile, Mn-doped CsPb(Cl/Br)3PQDs maintains the same crystal structure as CsPb(Cl/Br)3 PQDs. Importantly, it was found that the activation energy of CsPb(Cl/Br)3 PQDs after manganese doping increased from 65.1 meV to 222.8 meV through the high and low temperature PL test of 80 K–500 K. The crystal structure of CsPb(Cl/Br)3 PQDs is more stable due to the introduction of manganese ion, and the thermal stability is significantly improved. In this study, manganese doped CsPb(Cl/Br)3 PQDs with good crystallinity and thermal stability was rapidly synthesized by a simple supersaturation crystallization method at room temperature, which opened up a new way to improve the stability of PQDs and explore other non-toxic metal elements to replace Pb2+.

3D Printing of Luminescent Perovskite Quantum Dot–Polymer Architectures

AbstractOrganic–inorganic perovskite quantum dot (PQD)–polymer composites are emerging optoelectronic materials with exceptional properties that are promising widespread application in next‐generation electronics. Advances in the utilization of these materials depend on the development of suitable fabrication techniques to create 3D architectures composed of PQD–polymer for sophisticated optoelectronics. This study introduces a straightforward and effective method for producing 3D architectures of PQD‐encapsulated high‐performance composites (PQD‐HPCs) through direct‐ink writing (DIW). This method employs an ink composed of prefabricated PQDs and hydroxypropyl cellulose (HPC) in dichloromethane (DCM). HPC, an appropriate organic‐soluble polymer, exhibits optical transparency in the highly volatile DCM and enables the formulation of a stable, room‐temperature extrudable ink. The architectures, which are printed by adjusting the halide ratios (Cl, Br, and I) for the compositions of CH3NH3PbBr1.5I1.5, CH3NH3PbBr3, and CH3NH3PbBr1.5Cl1.5, exhibit single peak photoluminescence emissions of red (639 nm), green (515 nm), and blue (467 nm). Optimizing the printing parameters of DIW enables the precise fabrication of programmed and complex PQD‐HPC 3D architectures for advanced anti‐counterfeiting and information encryption. This method has the potential to enhance the functionality of modern printed electronic devices significantly.

Highly luminescent CsPbX3/PMMA (X=Br, I) composites with improved stability for full-color Micro-LED displays

Inorganic metal halide perovskite quantum dots (PQDs) have recently emerged as promising candidates for color conversion materials in Micro-LED displays, due to their outstanding color purity, high absorption coefficient, tunable emission wavelength. However the inferior stability and undesirable photoluminescence quantum yield (PLQY) restrict their particle applications. Herein, CsPbX3/PMMA (X = Br, I) composites with improved stability and optical performance were successfully prepared by a general and mild in-situ polymerization strategy. The ester carbonyl (CO) group in MMA formed complexes with Pb2+, leading to the in-situ thermal polymerization of polymethyl methacrylate (PMMA) under the action of the initiator. The multifunctional PMMA can efficiently passivate halogen vacancies while acting as a barrier against the degradation caused by heat, water, and oxygen. As a result, the PLQYs and stability of PMMA-coated CsPbX3 PQDs have been significantly improved. When implementing CsPbX3/PMMA/PDMS composites as color conversion layers in Micro-LEDs, they achieve an impressive color gamut of 127.23% with excellent stability. We believe our work will stimulate the exploration of perovskite/polymer composites for industrial Micro-LED applications.

Enhanced Cyan Photoluminescence and Stability of CsPbBr3 Quantum Dots Via Surface Engineering for White Light‐Emitting Diodes

AbstractThe emission of cyan light (470‐500 nm) plays a vital role in the visible light spectrum and is essential for applications such as lighting, displays, and optical communication. Inorganic cesium lead bromide perovskite quantum dots (CsPbBr3 PQDs) have made significant progress in the field of luminescence materials and devices, however, the lack of techniques to obtain highly emissive and stable cyan‐emitting CsPbBr3 PQDs has limited their device applications. Here, it is demonstrated that the complete surface passivation by treatment of didodecyldimethylammonium bromide (DDAB) and lead bromide, which can enhance the photoluminescence and stability of cyan emitting CsPbBr3 PQDs. In particular, the photoluminescence quantum yield of CsPbBr3 QDs can be greatly improved from 10.5% to 83.8%. Through an effective PMMA passivation, the obtained stable and bright CsPbBr3 PQDs composite films as the cyan color converters can effectively emit the cyan light to fill the “cyan gap” of white light‐emitting diode (WLED). The color rendering index value of such WLED is remarkably enhanced from 73.6 to 82.5. This study paves the way for the application of PQD color converters in the next generation of full‐visible‐spectrum WLED lighting.

Modulation of optical properties for lighting applications based on CsPbBr3−xIx quantum dot doped glasses

All inorganic halide perovskite quantum dots (PQDs) exhibit excellent optical properties and have been intensively exploited for diverse applications in the field of optoelectronics. However, their inherent frangibility remains an enormous challenge for both practical applications and scientific research. The recently emerged oxide glasses doped with such PQDs exhibit high stability against degradation, which is promising for practical applications. Here, borosilicate glasses doped with CsPbBr3−xIx PQDs were prepared by the traditional melt-quenching and subsequent annealing process. By introducing alkaline metal oxides as the glass network modifier to adjust glass network structure, the optical properties of the precipitated PQDs are significantly enhanced. The photoluminescence (PL) intensity and photoluminescence quantum yield (PLQY) can be enhanced by up to 200 % and 29 % for the sample fabricated under optimal conditions, respectively. By leveraging the strong PL of the developed PQD-doped glasses, we demonstrate the fabrication of phosphor-converted light emitting devices for white light illumination and plant illumination based on samples with PL peak wavelengths at approximately 570 nm and 650 nm, respectively.

Crystallization engineering in PVDF enables ultrastable and highly efficient CsPbBr3 quantum dots film for wide color gamut Mini-LED backlight

The polymeric composite films incorporating inorganic lead halide perovskite quantum dots (CsPbX3 QDs, X = Cl, Br or I) are promising color conversion layers for wide gamut display devices such as Mini-LED backlight-based televisions. However, the relatively low emission efficiency and poor stability of these composite films present significant challenges for practical applications. In this study, we present a novel low-temperature in-situ crystallization strategy to prepare CsPbBr3/PVDF composite film through a rational designed of precursor, solvent and polymer structure. The strong interaction between PVDF and perovskite QDs via Lewis acid-base interaction allows for precise control over the crystallization and passivation of perovskite QDs. The optimized CsPbBr3/PVDF film exhibits bright emission with a photoluminescence quantum yield (PLQY) of up to 70 %, surpassing those of other CsPbBr3/polymers counterparts. Furthermore, the films demonstrate remarkable stability, retaining over 90 % of their original PLQY even after 50 days of aging under various environmental conditions such as exposure to air, immersion in water and blue light irradiation. By integrating the green and red emissive CsPbX3/PVDF films with blue Mini-LEDs, we successfully fabricate a prototype liquid crystal display (LCD) with an outstanding wide color gamut (128 % of NTSC 1931). These performances outperform that of commercial white-LED-based LCDs, highlighting the immense potential of CsPbX3/PVDF for high-definition display applications in the future.

Two-Step Performance Optimization of CsPbBr3 Perovskite Nanocrystals for Wide Color Gamut Displays

Owing to their composition-tunable and narrow emissions and high photoluminescence quantum yield (PLQY), inorganic halide perovskite quantum dots (IPQDs) are a promising option for wide color gamut displays. However, their practical applications have been limited by their lattice structure instability and surface defect states. Herein, CsPbBr3:KBF4@SiO2 with improved stability and optical properties is successfully synthesized with a two-step optimization of fluorine (F) anion doping and SiO2 in situ coating. Compared with bromide (Br), higher electronegativity and a smaller radius of F lead to stronger binding energy with Pb2+. Also, F anions can occupy surface Br vacancies. Then, benefiting from the acidic environment provided by BF4− hydrolysis, tetraethyl orthosilicate (TEOS) can be more easily hydrolyzed on the CsPbBr3:KBF4 surface to generate SiO2 coating, thus further passivating lattice defects and improving environmental stability. Importantly, the PLQY of CsPbBr3:KBF4@SiO2 achieves 85%, and the stability has been greatly improved compared with pure CsPbBr3. Finally, CsPbBr3:KBF4@SiO2/PDMS, CsPbI3/PDMS, and CsPbCl3/PDMS composites with narrow emissions are applied to replace traditional phosphors as color converters for direct-view light-emitting diode (LED) displays or liquid crystal display (LCD) backlights. The color gamut reaches 118.22% under the NTSC standard. Concerning the display field, it suggests likely applications in the future.

In situ and General Multidentate Ligand Passivation Achieves Efficient and Ultra-Stable CsPbX3 Perovskite Quantum Dots for White Light-Emitting Diodes.

Inorganic CsPbX3 perovskite quantum dots (PeQDs) show great potential in white light-emitting diodes (WLEDs) due to excellent optoelectronic properties, but their practical application is hampered by low photoluminescence quantum yield (PLQY) and especially poor stability. Herein, we developed an in-situ and general multidentate ligand passivation strategy that allows for CsPbX3 PeQDs not only near-unit PLQY, but significantly improved stability against storage, heat, and polar solvent. The enhanced optical property arises from high effectiveness of the multidentate ligand, diethylenetriaminepentaacetic acid (DTPA) with five carboxyl groups, in passivating uncoordinated Pb2+ defects and suppressing nonradiative recombination. First-principles calculations reveal that the excellent stability is attributed to tridentate binding mode of DTPA that remarkably boosts the adsorption capacity to PeQD core. Finally, combining the green and red PeQDs with blue chip, we demonstrated highly luminous WLEDs with distinctly enhanced operation stability, a wide color gamut of 121.3% of national television system committee, standard white light of (0.33,0.33) in CIE 1931, and tunable color temperatures from warm to cold white light readily by emitters' ratio. This study provides an operando yet general approach to achieve efficient and stable PeQDs for WLEDs and accelerates their progress to commercialization.

Recent Progress of Organic–Inorganic Hybrid Perovskite Quantum Dots: Preparation, Optical Regulation, and Application in Light‐Emitting Diodes

AbstractOrganic–inorganic hybrid perovskite quantum dots (QIHP‐QDs) have aroused widespread interest due to their superior photoelectric performance, quantum confinement effect, excellent photoelectric property, color‐tunability, and high photoluminescence quantum yield (PLQY) especially for QD‐based light‐emitting diodes (QLEDs). It is worth noting that a diverse selection of organic cations brings more adjustable optical properties to OIHP‐QDs compared with all‐inorganic perovskite QDs; thus the research on OIHP‐QDs has become a hit subject over recent years. This review summarizes the latest progress in synthesis strategy and optical property regulation of OIHP‐QDs in conjunction with the recent developments of their application in QLEDs. In addition, the current challenges limiting the applicability of QIHP‐QDs are discussed, and the development of OIHP‐QDs in the future is proposed.

In-situ growth of inorganic perovskite quantum dots in MOF-5: significantly enhanced luminous intensity and stability

In-situ growth of inorganic perovskite quantum dots in MOF-5: significantly enhanced luminous intensity and stability

Efficient Charge Transfer in the Perovskite Quantum Dot-Hemin Biocomposite: Is This Effective for Optoelectronic Applications?

Inorganic perovskite quantum dots (PQDs) have great potential for optoelectronic applications as a result of their tunable optical properties, significant absorption coefficient, and high mobility. Combining PQDs with molecular adsorbates offers exciting possibilities for future applications, making it important to study interfacial electron transfer in PQD-molecular composites. Here, we present a study of PQD and hemin composites (PQD-hemin) to understand how their interfacial electron transfer dynamics are affected by adsorbate and PQD properties. Our femtosecond ultrafast transient absorption and time-resolved photoluminescence (TRPL) studies reveal that hot carrier relaxation, charge separation, and charge recombination processes are significantly impacted in the PQD-hemin composite system under different excitations, both higher and lower energy. Additionally, our alternating current (AC)- and direct current (DC)-bias-driven electrical studies show that, despite efficient charge separation in the PQD-hemin composite system, the light-induced transient photocurrent drops. The findings on the PQD-molecular composite will give useful outlooks for designing a variety of optoelectronic devices.

Stability of self-encapsulated CsPbX3@PbX(OH)(X=Cl,Br) perovskite quantum dots in polar solvents

Inorganic halide perovskite quantum dots has excellent optical and photoelectric properties, so it has great potential in photovoltaic, photoelectric devices, display lighting, medical detection and other fields. However, its commercial application is hampered by its instability. In this paper, the perovskite quantum dots encapsulated by PbX (OH)(X = Cl,Br) can obtain hexahedral CsPbBr3@PbBr(OH), cube CsPbCl3@PbCl(OH) and spindle CsPbCl3@PbBr(OH) between hexahedron and cube. The core-shell encapsulation and interchange combination are realized. Before and after encapsulation, the color coordinates of CsPbX3 (X = Cl,Br) perovskite quantum dots basically did not change, no other crystal phases were found in the XRD lines, which indicatied that the PbX (OH) (X = Cl,Br) encapsulation layer did not change the crystal structure of perovskite quantum dots. PbX (OH) (X = Cl,Br) encapsulation layer plays the role of water-blocking layer and protective layer, which greatly improves the stability of CsPbX3 (X = Cl,Br) perovskite quantum dots in polar solvents. After encapsulation, the photoluminescence quantum yield (PLQY) and time-resolved photoluminescence decay performance of CsPbX3 (X = Cl,Br) perovskite quantum dots are greatly improved. The surface passivation and trap density of perovskite nanocrystals can be reduced by PbX (OH) (X = Cl,Br) wrapping, which extends the fluorescence life of CsPbX3 (X = Cl,Br) and improving the PL stability of perovskite structure. Room temperature (RT) crystallization method does not require inert gas protection, high temperature and high pressure conditions. It also has good repeatability, which provides a better alternative to hot injection. Meanwhile, the improvement of package stability provides a broader prospect for the application and promotion of lead halide perovskite.

Phase regulation of Cs4PbBr6/CsPbBr3 in tellurate germanate glasses induced by P2O5

All inorganic perovskite quantum dots (QDs) have broad applications due to its unique photoelectric properties. At present, a large number of QDs embed glasses of three-dimensional (3-D) CsPbBr3 cubic phase or zero dimensional (0-D) Cs4PbBr6 hexagonal phase have been reported, but the phase regulation between 0-D and 3-D has not been deeply studied only by the adjustment of the glass network topology. In this paper, Cs4PbBr6/CsPbBr3 QDs were successfully synthesized in tellurite germanate glass by high-temperature melt-quenching combined with in-situ crystallization, and their luminescence properties, structures, and phase regulation fundamentals in glasses were investigated in depth. The introduction of P2O5 increases the ratio of [TeO4]/[TeO3] units in the tellurite germanate glasses, resulting in a more compact glass network and changing the growth environment of QDs. When the content of the nucleating agent P2O5 was increased to 3% (mass fraction), the crystalline phase of QDs realized the regulate from 0-D hexagonal phase to 3-D cubic phase. The regulation from Cs4PbBr6 to CsPbBr3 is accompanied by a blue-shifted emission peak from 519 to 482 nm, and the synthesized QDs glasses all have good long-term stability. The QDs glasses obtained in the experiment has great potential in the application of white light emitting diodes.

Engineering CsPbX3 (X = Cl, Br, I) Quantum Dot-Embedded Borosilicate Glass through Self-Crystallization Facilitated by NaF as a Phosphor for Full-Color Illumination and Laser-Driven Projection Displays.

All inorganic perovskite (CsPbX3, X = Cl, Br, I) quantum dot (QD) glass samples are considered the next generation of lighting materials for their excellent luminescence properties and stability, but crystallization conditions are difficult to control, which often leads to the inhomogeneous crystallinity of QDs. Here, we provided evidence that the presence of sodium fluoride induced self-crystallization of CsPbBr3 QDs during routine glass formation without the need for additional heat treatment. We showed that NaF simultaneously affected the network structure of glass and promoted the formation of CsPbBr3 QDs, that is, Na+ ions entered the glass network skeleton, partially interrupting the network structure, while the strong electronegativity of F- ions attracted Cs+ and Pb2+ ions into the gaps formed in the glass networks that had been loosened up by Na+ ions, which reduced the activation energy of crystallization processes. Our results showed that NaF-induced CsPbBr3 QDs glass had excellent thermal stability, high photoluminescence quantum efficiency (49%), and luminescent stability under high-power laser irradiation. Finally, this work also demonstrated the general applicability of this method in the making of a series of CsPbX3 (X = Cl, Br, I) QD glass samples by NaF-induced self-crystallization, which drastically expanded the color gamut to a range of full spectrum for luminescence and laser-driven projection displays. We believe that the work presented here represents a new direction for the research and development of full-color gamut inorganic perovskite quantum dot glass samples, which could have a significant impact on the future applications of laser-driven projection displays as well.