CsPbBr3 Perovskite Quantum Dots Research Articles

Identification and Dynamics of Microsecond Long-Lived Charge Carriers for CsPbBr3 Perovskite Quantum Dots, Featuring Ambient Long-Term Stability.

We analyze the stability and photophysical dynamics of CsPbBr3 perovskite quantum dots (PeQDs), fabricated under mild synthetic conditions and embedded in an amorphous silica (SiOx) matrix (CsPbBr3@SiOx), underscoring their sustained performance in ambient conditions for over 300 days with minimal optical degradation. However, this stability comes at the cost of a reduced photoluminescence efficiency. Time-resolved spectroscopic analyses, including flash-photolysis time-resolved microwave conductivity and time-resolved photoluminescence, show that excitons in CsPbBr3@SiOx films decay within 2.5 ns, while charge carriers recombine over approximately 230 ns. This longevity of the charge carriers is due to photoinduced electron transfer to the SiOx matrix, enabling hole retention. The measured hole mobility in these PeQDs is 0.880 cm2 V-1 s-1, underscoring their potential in optoelectronic applications. This study highlights the role of the silica matrix in enhancing the durability of PeQDs in humid environments and modifying exciton dynamics and photoluminescence, providing valuable insights for developing robust optoelectronic materials.

High responsivity photodetector based on MEH-PPV/CsPbBr3 heterojunction

Perovskite quantum dots (QDs) and organic materials have great research potential in the field of optoelectronic devices. In this paper, MEH-PPV/CsPbBr3 heterojunction photodetectors (PDs) are prepared by spin coating method based on the good photoelectric properties of CsPbBr3 perovskite QDs and MEH-PPV. The MEH-PPV/CsPbBr3 heterojunction improves the energy level arrangement, and CsPbBr3 QDs can passivate the surface defects of MEH-PPV films to achieve effective charge separation and transfer, thus inhibiting the dark current and improving the photoelectric performance of the device. Under 532 nm laser irradiation, the responsivity (R) of MEH-PPV/CsPbBr3 heterojunction PD is 11.98 A W−1, the specific detectivity (D*) is 6.98 × 1011 Jones, and the response time is 15/16 ms. This work provides experience for the study of perovskite QDs and organic materials heterojunction optoelectronic devices.

Efficient Homojunction/Heterojunction Photocatalyst via Integrating CsPbBr3 Quantum Dot Homojunction with TiO2 for Degradation of Organic Dyes.

A novel TiO2-CsPbBr3(Q) photocatalyst is proposed and rationally constructed, where CsPbBr3 perovskite quantum dots (QDs) of various sizes inside mesopore TiO2 (M-TiO2) are integrated. These perovskite QDs, generated in situ within M-TiO2, establish a type-II homojunction. Interestingly, a Z-scheme heterojunction is simultaneously formed at the interface between CsPbBr3 and TiO2. Due to the coexistence of the type-II homojunction and the Z-scheme heterojunction, photogenerated electrons are effectively transferred from TiO2 to CsPbBr3, thereby suppressing carrier recombination and thus enhancing the degradation of rhodamine B (RhB). Compared with pure CsPbBr3 and TiO2, TiO2-CsPbBr3(Q) shows significantly enhanced photocatalytic performance for RhB degradation. The degradation efficiency of RhB in the presence of the TiO2-CsPbBr3(Q) attains 97.7% in 5 min under light illumination, representing the highest efficiency observed among photocatalysts based on TiO2. This study will facilitate the development of superior semiconductor catalysts for photocatalytic applications.

CsPbBr3 PQDs in EuAPO-5 Zeolite: Highly Stable Fluorescent-Traffic-Light Sensor for Point-of-Care Response of Tetracycline and Temperature

Fluorescent point-of-care (POC) sensors with specific target recognition capability through signaling mechanisms have promising applications in areas such as environmental monitoring and food detection. Herein, a solvent-free method was developed to prepare a novel POC sensor based on dual-luminescent CsPbBr3@EuAPO-5 composite that enabled the multiple sensing of tetracycline (TC) and temperature in a unique fluorescent-traffic-light manner. Benefiting from the confinement effect of EuAPO-5 zeolite, the CsPbBr3 perovskite quantum dots (PQDs) exhibits extraordinary luminescent stability even soaking in water for 30 days. During TC detection, the effective absorbed energy transfer from TC to Eu3+ in EuAPO-5 zeolite through the antenna effect enhances the red emission of Eu3+, and meanwhile a internal filtering effect (IFE) between the TC molecule and CsPbBr3 PQDs results in the green emission quenching of CsPbBr3. Combining the colorimetric determination using a smartphone-based analysis application (APP), the CsPbBr3@EuAPO-5 can serve as a portable POC sensor for TC monitoring in aqueous solution with a low detection limit of 0.013µM in a linear range of 0-140µM. Besides, ratiometric temperature sensing behavior of CsPbBr3@EuAPO-5 for high temperature warning in a fluorescent-traffic-light manner was also achieved, boosting a high sensitivity of 27.63% K-1 (at 383K) and a temperature resolution greater than 0.0035K in 293-383K. This work provides a novel bifunctional CsPbBr3 PQDs based sensor for reliable and visual detection of TC concentration and temperature, laying the foundation for the development of high-quality POC sensors with exceptional sensitivity and practicality.

G-C3N4 as ballistic electron transport “Tunnel” in CsPbBr3-based ternary photocatalyst for gas phase CO2 reduction

Perovskite CsPbBr3 quantum dot shows great potential in artificial photosynthesis, attributed to its outstanding optoelectronic properties. Nevertheless, its photocatalytic activity is hindered by insufficient catalytic active sites and severe charge recombination. In this work, a CsPbBr3@Ag-C3N4 ternary heterojunction photocatalyst is designed and synthesized for high-efficiency CO2 reduction. The CsPbBr3 quantum dots and Ag nanoparticles are chemically anchored on the surface of g-C3N4 sheets, forming an electron transfer tunnel from CsPbBr3 quantum dots to Ag nanoparticles via g-C3N4 sheets. The resulting CsPbBr3@Ag-C3N4 ternary photocatalyst, with spatial separation of photogenerated carriers, achieves a remarkable conversion rate of 19.49 μmol·g−1·h−1 with almost 100 % CO selectivity, a 3.13-fold enhancement in photocatalytic activity as compared to CsPbBr3 quantum dots. Density functional theory calculations reveal the rapid CO2 adsorption/activation and the decreased free energy (0.66 eV) of *COOH formation at the interface of Ag nanoparticles and g-C3N4 in contrast to the g-C3N4, leading to the excellent photocatalytic activity, while the thermodynamically favored CO desorption contributes to the high CO selectivity. This work presents an innovative strategy of constructing perovskite-based photocatalyst by modulating catalyst structure and offers profound insights for efficient CO2 conversion.

Synthesis of Size-Adjustable CsPbBr3 Perovskite Quantum Dots for Potential Photoelectric Catalysis Applications.

As a direct band gap semiconductor, perovskite has the advantages of high carrier mobility, long charge diffusion distance, high defect tolerance and low-cost solution preparation technology. Compared with traditional metal halide perovskites, which regulate energy band and luminescence by changing halogen, perovskite quantum dots (QDs) have a surface effect and quantum confinement effect. Based on the LaMer nucleation growth theory, we have synthesized CsPbBr3 QDs with high dimensional homogeneity by creating an environment rich in Br- ions based on the general thermal injection method. Moreover, the size of the quantum dots can be adjusted by simply changing the reaction temperature and the concentration of Br- ions in the system, and the blue emission of strongly confined pure CsPbBr3 perovskite is realized. Finally, optical and electrochemical tests suggested that the synthesized quantum dots have the potential to be used in the field of photocatalysis.

Improved photoluminescence stability and defect passivation in SbBr3 post-treated CsPbBr3 quantum dots under ambient conditions.

Inorganic cesium lead halide perovskites have evoked wide popularity because of their excellent optoelectronic properties, high photoluminescence (PL) quantum yield (PLQY), and narrowband emission. Here, cesium lead bromide (CsPbBr3 ) quantum dots (QDs) were synthesized via the ligand-assisted re-precipitation method. Post-synthesis treatment of CsPbBr3 QDs using antimony tribromide improved the PL stability and optoelectronic properties of the QDs. In addition, the PLQY of the post-treated sample was enhanced to 91% via post-treatment, and the luminescence observed was maintained for 8 days. The post-synthesis treatment ensured defect passivation and improved the stability of CsPbBr3 perovskite QDs. High-resolution transmission electron microscopy revealed the presence of more ordered, uniform-sized CsPbBr3 QDs after post-synthesis treatment, and the uniformity of the sample improved as the day passed. The formation of a mixed crystal phase was observed from X-ray diffraction in both as-synthesized, as well as post-treated QDs samples with the possibility of a polycrystalline nature in the post-treated CsPbBr3 QDs as per the selected area electron diffraction pattern. The X-ray photoelectron spectroscopy spectra confirmed the presence of antimony and the possibility of defect passivation in the post-treated samples. These QDs can act as potential candidates in various optoelectronic applications such as photodetectors and light-emitting diodes due to their high PLQY and longer lifetime.

A smartphone-assisted fluorescent sensing platform for ochratoxin A using Mn-doped CsPbBr3 perovskite quantum dots embedded in the mesoporous silica as a ratiometric probe

Food sources are susceptible to contamination with ochratoxin A (OTA), which is a serious threat to human health. Thus, the construction of novel, simple sensing platforms for OTA monitoring is of utmost need. Manganese-doped lead halide perovskite quantum dots encapsulated with mesoporous SiO2 (Mn-CsPbBr3 QDs@SiO2) were prepared here and used as a ratiometric fluorescent probe for OTA. Mn-CsPbBr3 QDs, synthesized at room temperature, exhibit dual emission with maximum wavelengths of 440 and 570 nm and, when embedded in the SiO2 layer, produce a stable and robust photoluminescence signal. By adding OTA to the probe, emission at 440 nm increases while emission at 570 nm decreases, so a ratiometric response is obtained. Experimental variables affecting the probe signal were studied and optimized and the mechanism of sensing was discussed. This ratiometric sensor demonstrated excellent selectivity and low detection limit (4.1 ng/ml) as well as a wide linear range from 5.0 to 250 ng/ml for OTA. A simple portable smartphone-based device was also constructed and applied for the fluorescence assay. With different OTA concentrations, the multicolor transition from pink to blue under a UV lamp led to simple visual and smartphone-assisted sensing of OTA by using a color analyzing application. Satisfactory recoveries in black tea, coffee, moldy fig and flour samples confirmed the reliability of the assay. The accuracy of the probe was proved by comparison of the results with high-performance liquid chromatography (HPLC).

Large-scale preparation of CsPbBr3 perovskite quantum dot/EVA composite adhesive film by melting for crystal silicon solar cell

Silicon solar cell is the most mature photovoltaic conversion device, and in order to further improve the performance of the device, application of downshifting films has become a research hotspot. In this paper, CsPbBr3 perovskite quantum dot/EVA composite adhesive film was prepared by melting method with CsPbBr3 perovskite quantum dot film under solution processing as masterbatch and EVA particles as excipient. The effect of synthesis conditions on the luminescence properties of the composite films were thoroughly studied. The optimized CsPbBr3 perovskite quantum dot/EVA composite adhesive film has excellent performance, and its light transmission reaches 85%. The CsPbBr3 perovskite quantum dot/EVA composite adhesive film absolutely improves the efficiency of silicon solar cells by 1.08%, which is much higher than that of pure EVA adhesive film (0.63%). In addition, the device efficiencies have almost no change after 30 d in the air, maintaining the working stability of the device and contributing to industrial applications. This study provides a novel, industrial and low-cost synthesis route for the synthesis of CsPbBr3 perovskite quantum dot/EVA composite adhesive film, which is expected to have broad application.

Super stable and water-dispersible CsPbBr3 perovskite quantum dots for the efficient detection of Cu (II) and glutathione

Perovskite quantum dots (PQDs) have made substantial advances in solar cells, light-emitting diodes, and photocatalysis due to their distinctive optical and electrical properties. The intrinsic instability of PQDs restricts their practical applications, which makes using them in the food sector difficult. The present work indicates that the long-term stability of ionic crystals by using the two-ligand mechanism of 4-bromo-butyric acid (BBA) and oleylamine (OLA) can provide prospects for the use of PQDs in the food industry. The results reveal that monodispersed CsPbBr3@BBA QDs, obtained in water, exhibit high photoluminescence quantum yields (PLQYs). Notably, the photoluminescence characteristics of CsPbBr3@BBA QDs remained remarkably stable even after dispersing the materials in an aqueous solution for 140 h, indicating the robust structural stability of CsPbBr3@BBA QDs. We used the CsPbBr3@BBA QDs to selectively detect the presence of Cu2+ in food samples such as ordinary fruits and tea. The results exhibited a good linearity within the range of 0 to 80 μM, with the limit of detection of 0.8 μM. At the same time, this sensor proposed here possessed a linear range of 0 to 250 μM and a limit of detection of 2.84 μM for glutathione (GSH) detection. Furthermore, it is shown that the QDs-Cu2+ fluorescent probe also displayed selective fluorescence recovery after exposure to GSH. The low cost and ease of preparation of this sensor offer enormous industrialization potential and opportunity, thereby accelerating the development of the sensor in the field of food safety.

Extremely long-lived charge separation and related carrier spin excitation in CsPbBr3 perovskite quantum dots with an electron acceptor benzoquinone

Extremely long-lived charge separation and related carrier spin excitation in CsPbBr3 perovskite quantum dots with an electron acceptor benzoquinone

Ligand-mediated exciton dissociation and interparticle energy transfer on CsPbBr3 perovskite quantum dots for efficient CO2-to-CO photoreduction

Perovskite quantum dots (PQDs) hold immense potential as photocatalysts for CO2 reduction due to their remarkable quantum properties, which facilitates the generation of multiple excitons, providing the necessary high-energy electrons for CO2 photoreduction. However, harnessing multi-excitons in PQDs for superior photocatalysis remains challenging, as achieving the concurrent dissociation of excitons and interparticle energy transfer proves elusive. This study introduces a ligand density-controlled strategy to enhance both exciton dissociation and interparticle energy transfer in CsPbBr3 PQDs. Optimized CsPbBr3 PQDs with the regulated ligand density exhibit efficient photocatalytic conversion of CO2 to CO, achieving a 2.26-fold improvement over unoptimized counterparts while maintaining chemical integrity. Multiple analytical techniques, including Kelvin probe force microscopy, temperature-dependent photoluminescence, femtosecond transient absorption spectroscopy, and density functional theory calculations, collectively affirm that the proper ligand termination promotes the charge separation and the interparticle transfer through ligand-mediated interfacial electron coupling and electronic interactions. This work reveals ligand density-dependent variations in the gas-solid photocatalytic CO2 reduction performance of CsPbBr3 PQDs, underscoring the importance of ligand engineering for enhancing quantum dot photocatalysis.

Enhancing the performance of PbS:CsPbBr3 bulk-heterojunction photodetectors by treating with imidazolium-based ionic liquids.

All-inorganic lead halide perovskites and quantum dots (QDs) have gained significant attention since their emergence, owing to their immense potential for applications in optoelectronic devices. Here, enhanced-performance broadband photodetectors based on the bulk-heterostructure of a CsPbBr3 perovskite and PbS colloidal quantum dots (CQDs) are presented, and 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM]BF4) ionic liquids as a dual-purpose additive were introduced in the blended film to regulate the surface of QDs by facilitating surface passivation, adjusting energy levels, and coupling with longer alkyl chains as compared to iodide ions (I-). As a result, a superior-quality bulk-heterostructure based photodetector with long-term stability was obtained, showing outstanding performance in photodetection across the visible to near-infrared wavelength range, demonstrating a high photoresponsivity of 22.4 A W-1 with a response time of 16.2 ms and a specific detectivity of 1.58 × 1014 Jones under 405 nm illumination. Thus, this work provides a novel modification strategy for PbS:CsPbBr3 as a promising material for novel optoelectronics.

Stability and photocurrent enhancement of photodetectors by using core/shell structured CsPbBr3/TiO2 quantum dots and 2D materials.

Ultra-stable CsPbBr3 perovskite quantum dots (QDs) were prepared, and the performance of the photodetector fabricated from them was enhanced by 2D material incorporation. This multi-component photodetector appears to have good stability in the ambient utilization environment. All inorganic CsPbBr3 QDs are potential candidates for application in photodetection devices. However, QDs have several issues such as defects on the QD surface, degradation under environmental conditions, and unfavorable carrier mobility limiting the high performance of the photodetectors. This work addresses these issues by fabricating a core/shell structure and introducing 2D materials (MXenes, Ti3C2Tx) into the device. Here, three types of photodetectors with QDs only, QDs with a core/shell structure, and QDs with a core/shell structure and MXenes are fabricated for systematic study. The CsPbBr3/TiO2 photodetector demonstrated a two times photocurrent enhancement compared to bare QDs and had good device stability after TiO2 shell coating. After introducing Ti3C2Tx into CsPbBr3/TiO2, a significant photocurrent enhancement from nanoampere (nA) to microampere (μA) was observed, revealing that MXenes can improve the photoelectric response of perovskite materials significantly. Higher photocurrent can avoid signal interference from environmental noise for better practical feasibility. This study provides a systematic understanding of the photocurrent conversion of perovskite quantum dots that is beneficial in advancing optoelectronic device integration, especially for flexible wearable device applications.

Anion exchange as an excellent tool to obtain highly efficient blue-emitting all-inorganic perovskite quantum dots

In this study, we examined the dynamic photoluminescence (PL) characteristics of all-inorganic perovskite quantum dots (QDs) during the anion-exchange process between bromide and chloride ions. CsPbBr3 QDs were synthesized using an ultrasound-induced hot-injection route. These QDs were then treated with TMS-Cl solutions, resulting in the formation of blue-emitting CsPb(Br/Cl)3 QDs with high quantum efficiencies. Even the addition of a small amount of TMS-Cl to the CsPbBr3 solution led to a noticeable blue shift of the emission. Moreover, surface treatment with a small amount of TMS-Cl also resulted in an enhanced PL quantum efficiency (PLQE) owing to surface trap removal. Exposure of the CsPbBr3 perovskite QDs solution to a higher amount of TMS-Cl yielded deep-blue-emitting QDs (412 nm) with a very high PLQE of 57 %.

Classical molecular dynamics simulations of CsPbBr3 perovskite quantum dots embedded sodium borosilicate glasses

We have simulated the configuration of perovskite CsPbBr3 quantum dot (QD), sodium borosilicate (SBS) glass matrix, and the combination of these two, namely CsPbBr3 QDs embedded SBS glass. We delineate a microscope porthole containing ∼100,000 atoms and with a dimension of ∼30 nm × 30 nm × 1 nm, using the classical molecular dynamics (CMD) benefiting from graphics processing unit (GPU) acceleration. We quantify the structural properties of glass matrix and determined the crystallization of QDs, in excellent agreement with experimental observations. Based on analysis the of boron coordination, structural undulation influenced by the K value (KSiO2/B2O3), we demonstrate the significant compositional repulsion in the combination derived from electronegative nonmetal elements, namely oxygen (O) and bromine (Br). As the K value decreases, indicating an increase in the proportion of B2O3 and a decrease in the proportion of SiO2, the [BO3]/[BO4] ratio increases, resulting in a glass matrix with a stronger repulsive 'anionic sea' and a more relaxed encapsulated environment for CsPbBr3 QD. This creates greater repulsion for the allocation of oxide and bromide, and a more suitable space for the crystallization of CsPbBr3 clusters, which in turn regulates the formation of CsPbBr3 QDs. These results constructively extend our understanding of the microstructure of CsPbBr3 QDs embedded SBS glasses, and provide valuable insights for the engineering of CsPbBr3 QDs in SBS glasses on high luminescent CsPbBr3 QDs embedded glasses.

Net Gain at the Near‐Infrared from CsPbBr3 Quantum Dots Sensitized Nd3+‐activated Tellurite Glass Under Solar Excitation

AbstractLanthanide ions (Ln3+) doped near‐infrared (NIR) phosphors play a critical role in applications requiring a compact, reliable, and economical NIR light source, but as yet they suffer from weak and narrow‐band absorption because of intrinsic photophysical limitations of Ln3+. Here, CsPbBr3 perovskite quantum dots (PQDs) and Nd3+ co‐doped tellurite glassy phosphor is designed to significantly upgrade the NIR photoluminescence (PL) efficiency of Ln3+. Benefiting from the sensitization effect of the PQDs on Nd3+, the PL excitation band of Nd3+ is greatly extended, permitting far more excitation channels that are impossible for conventional Nd3+‐doped glass phosphors. Such glassy phosphors also show a good stability, and when coupled with a commercial UV (or blue) chip, a compact and low‐cost NIR phosphor‐converted LED (pc‐LED) is constructed with a photoelectric conversion efficiency of 2.25% and an output power of 2.55 mW. A proof‐of‐concept demonstration for night vision application is given using the NIR pc‐LED. The excellent overlap with the solar spectrum in the visible portion inspires us to explore the possibility of sunlight excitation, and a net gain of ≈5 dB cm−1 is obtained near the 1064 nm. The implications of the present study are enormous considering diverse combinations of PQDs and Ln3+ in GCs.

Energy transfer modulation of photoluminescence in glasses co-doped with Nd3+ and CsPbBr3 quantum dots

Nd3+ co-doped CsPbBr3 perovskite quantum dots (PQDs) glasses were prepared by conventional melt-quenching followed by a thermal treatment process. With the introduction of Nd2O3 to the parent glass, the optical properties of the CsPbBr3 PQDs are significantly improved. The energy transfer from CsPbBr3 PQDs to Nd3+ ions was investigated and confirmed by excitation and emission spectra. The results show that visible excitation band width for the near-infrared (NIR) emission of Nd3+ ions is significantly increased in the presence of PQDs. The strategy for modulation of the optical properties by the energy transfer between rare earth ions and PQDs in the glass matrix could be further utilized for spectral engineering of photonic glasses for optoelectronic applications.

The Combination of Upconversion Nanoparticles and Perovskite Quantum Dots with Temperature-Dependent Emission Colors for Dual-Mode Anti-Counterfeiting Applications.

Novel and high-security anti-counterfeiting technology has always been the focus of attention and research. This work proposes a nanocomposite combination of upconversion nanoparticles (UCNPs) and perovskite quantum dots (PeQDs) to achieve color-adjustable dual-mode luminescence anti-counterfeiting. Firstly, a series of NaGdF4: Yb/Tm UCNPs with different sizes were synthesized, and their thermal-enhanced upconversion luminescence performances were investigated. The upconversion luminescence (UCL) intensity of the samples increases with rising temperature, and the UCL thermal enhancement factor rises as the particle size decreases. This intriguing thermal enhancement phenomenon can be attributed to the mitigation of surface luminescence quenching. Furthermore, CsPbBr3 PeQDs were well adhered to the surfaces and surroundings of the UCNPs. Leveraging energy transfer and the contrasting temperature responses of UCNPs and PeQDs, this nanocomposite was utilized as a dual-mode thermochromic anti-counterfeiting system. As the temperature increases, the color of the composite changes from green to pink under 980 nm excitation, while it displays green to non-luminescence under 365 nm excitation. This new anti-counterfeiting material, with its high security and convenience, has great potential in anti-counterfeiting applications.

Defect-Passivated Photosensor Based on Cesium Lead Bromide (CsPbBr3) Perovskite Quantum Dots for Microbial Detection.

A defect-passivated photosensor based on cesium lead bromide (CsPbBr3) perovskite quantum dots (QD) was fabricated using parylene films, and the photosensor was applied for the microbial detection. The CsPbBr3 perovskite QDs were synthesized to be homogeneous in size under thermodynamic control, and the perovskite QD-based photosensor was fabricated using MoS2 flakes as the electron transfer layer. In this work, a parylene film with functional groups was deposited on a photosensor for physical protection (waterproof) and defect (halide vacancy) passivation of the perovskite QD. As the first effect of the parylene film, the physical protection of the perovskite QD from water was estimated by comparing the photosensor performance after incubation in water. As the second effect of the parylene, the interaction between the functional groups of the parylene film and the halide vacancies of the perovskite QDs was investigated through the bandgap, crystal structure, and trap-state density analysis. Additionally, density functional theory analysis on Mulliken charges, lattice parameters, and Gibbs free energy demonstrated the effect of the defect passivation by parylene films. Finally, the parylene-passivated QD-based photosensor was applied to the detection of two kinds of food-poisoning and gastroduodenal disease bacteria (Listeria monocytogenes and Helicobacter pylori).