CsPbBr3 Perovskite Research Articles

Deciphering the Energy Transfer Mechanism Across Metal Halide Perovskite-Phthalocyanine Interfaces.

Energy transfer processes in nanohybrids are at the focal point of conceptualizing, designing, and realizing novel energy-harvesting systems featuring nanocrystals that absorb photons and transfer their energy unidirectionally to surface-immobilized functional dyes. Importantly, the functionality of these dyes defines the ultimate application. Herein, CsPbBr3 perovskite nanocrystals (NCs) are interfaced with zinc phthalocyanine (ZnPc) dyes featuring carboxylic acid. The functionality is the photosensitization of singlet oxygen. The CsPbBr3@ZnPc nanohybrid is to the best of our knowledge the first example, in which an unusual Dexter-type singlet energy transfer between metal halide perovskite nanocrystals and phthalocyanine dyes enables singlet oxygen generation as a proof-of-concept application. A detailed temporal picture of the singlet energy transfer mechanism is made possible by combining key time-resolved spectroscopic techniques, that are, femtosecond, nanosecond, and microsecond transient absorption spectroscopy as well as time-correlated single photon counting, and target analyses. In fact, three excitonic components in the NCs govern a concerted Dexter-type energy transfer. The work illustrates the potential of CsPbBr3@ZnPc as a singlet photosensitizer of ZnPc to produce singlet oxygen (1O2) almost quantitatively while photoexciting CsPbBr3.

Flexible and stable piezoelectric nanogenerators based on monoclinic phase CsPbBr3 perovskite nanocrystals.

CsPbBr3 perovskite has garnered significant attention in the field of optoelectronics due to its exceptional photoelectric properties. In this study, we report the fabrication of a piezoelectric nanogenerator (PNG) composed of a composite of monoclinic phase CsPbBr3 nanocrystals and polydimethylsiloxane. This is the first instance of a PNG based on the monoclinic phase of CsPbBr3. The PNG device has been optimized to operate at a frequency of 30 Hz and exhibits impressive output performance, generating a peak-to-peak output voltage of 50 V, an output current of 5.5 μA and a power density of 2.5 μW cm-2 when subjected to an applied force of only 4.2 N over an effective area of 8 cm2. The energy generated by this PNG can be efficiently collected using capacitors with a high energy conversion efficiency of 21.7%. Furthermore, the output voltage of the PNG remains at 98.5% of its initial value after 20 days, demonstrating exceptional stability. This study highlights the great potential of CsPbBr3 perovskite materials for the simple and cost-effective fabrication of high-performance multifunctional piezoelectric energy harvesting devices.

Boosting charge transfer with MoS2-grafted MXene interlayers for high-efficiency all-inorganic CsPbBr3 perovskite solar cells with an ultrahigh voltage of 1.701 V

Two-dimensional MXene nanoflakes grafted with MoS2 QDs are used as multifunctional interlayers at the perovskite/carbon interface in all-inorganic CsPbBr3 perovskite solar cells, achieving a 10.70% efficiency with an ultrahigh Voc of 1.701 V.

Can fullerene derivative PCBM serve as an innovative hole transport material for CsPbBr3 perovskite solar cells?

Can fullerene derivative PCBM serve as an innovative hole transport material for CsPbBr3 perovskite solar cells?

Electron-beam-evaporated NiOX for efficient and stable semi-transparent perovskite solar cells and modules

Herein, thermally stable ST-PSCs have been fabricated by using vacuum deposited CsPbBr3 perovskite and electron-beam evaporation deposited NiOX. Furthermore, we achieved a champion efficiency of 5.5% for 5 cm × 5 cm mini-modules with an AVT of 49.1%.

Influence of Lewis basicity on the S2- induced synthesis of 0D Cs4PbBr6 hexagonal nanocrystals and its implications for optoelectronics.

Perovskite nanocrystals (NCs) with their excellent optical and semiconductor properties have emerged as primary candidates for optoelectronic applications. While extensive research has been conducted on the 3D perovskite phase, the zero-dimensional (0D) form of this promising material in the NC format remains elusive. In this paper, a new synthesis strategy is proposed. According to the Hard-Soft Acid-Base (HSAB) principle, a novel class of hexagonal semiconductor nanocrystals (Cs4PbBr6 HNCs) derived from 0D perovskite Cs4PbBr6 is synthesized by doping an appropriate amount of PbS precursor solution into bromide. These Cs4PbBr6 HNCs are characterized and compared in detail to CsPbBr3 cubic nanocrystals (CsPbBr3 CNCs) as a reference. The Cs4PbBr6 HNCs exhibit significantly enhanced photoluminescence (PL) compared to CsPbBr3 CNCs, with an external quantum efficiency (EQE) reaching 24.19%. Furthermore, they demonstrate superior UV stability compared to CsPbBr3 CNCs. Comparative analysis of their physical properties and morphology, along with detailed investigations into band structures, density of states, and lifetime decay through DFT calculations, is provided. The practical application potential is validated by encapsulating them into backlight LEDs, covering 121.5% and 90.7% of the color gamut of NTSC and Rec. Our research provides comprehensive insights into the photophysical properties of inorganic halide perovskite nanomaterials and explores their potential in the field of optoelectronics.

Effects of Polymer Matrix and Atmospheric Conditions on Photophysical Properties of a Cesium Lead Bromide (CsPbBr3) Perovskite Quantum Dot.

Understanding the environment-dependent stability and photoluminescence (PL) properties of advanced perovskite materials remains a challenge with conflicting views. Herein, we investigated the influence of the host matrix (poly(methyl methacrylate) (PMMA) and polystyrene (PS)) and atmospheric conditions (ambient and N2) on the PL properties of a CsPbBr3 perovskite quantum dot (PQD) using single-particle spectroscopy. Despite the same PL blinking mechanism, the PL properties of the PQD were considerably affected by the environmental conditions. The charge trapping and detrapping rates of the PQD were lower and higher, respectively, under ambient atmosphere than under N2 owing to surface defect passivation by oxygen. The frequency and rate of PQD decomposition were higher in the PMMA matrix than in the PS matrix under an ambient atmosphere. PS achieved superior PQD encapsulation owing to its higher affinity toward hydrophobic surface ligands because of its aromatic rings, thereby protecting the PQD surface from moisture and thus inhibiting decomposition.

Perovskite CsPbBr3 Quantum Dots on Aminated Silica with Enhanced Stability for Blue Light-Emitting Diode and Anti-Counterfeiting Applications

Perovskite CsPbBr₃ Quantum Dots on Aminated Silica with Enhanced Stability for Blue Light-Emitting Diode and Anti-Counterfeiting Applications

Bidentate Lewis Base Ligand-Mediated Surface Stabilization and Modulation of the Electronic Structure of CsPbBr3 Perovskite Nanocrystals.

The desorption of conventional ligands from the surface of halide perovskite nanocrystals (NCs) often causes their structural instability and deterioration of the optoelectronic properties. To address this challenge, we present an approach of using a bidentate Lewis base ligand, namely, 1,4-bis(diphenylphosphino)butane (DBPP), for the synthesis of CsPbBr3 NCs. The phosphine group of DBPP has a strong interaction with the PbBr2 precursor, forming a highly crystalline intermediate complex during the reaction. In the presence of oleic acid, the uncoordinated phosphine group of DBPP is converted into the phosphonium cation, which strongly binds to the surface bromide of the formed CsPbBr3 NCs through hydrogen bonding. Density functional theory calculations suggest that DBPP can strongly bind to the undercoordinated lead and surface bromide ions of CsPbBr3 NCs through its unprotonated and protonated phosphine groups, respectively. The robust binding of DBPP to the surface of perovskite NCs helps to preserve their structural integrity under various environmental stresses. Moreover, the electron density and energy levels are regulated in DBPP-capped CsPbBr3 NCs by the donation of electrons from the ligands to the NCs, resulting in their improved photocatalytic CO2 reduction performance. Our study highlights the potential of using bidentate ligands to stabilize the surface of perovskite NCs and modulate their optical and electronic properties.

All-Inorganic Perovskite Quantum-Dot Optical Neuromorphic Synapses for Near-Sensor Colored Image Recognition.

As the demand for the neuromorphic vision system in image recognition experiences rapid growth, it is imperative to develop advanced architectures capable of processing perceived data proximal to sensory terminals. This approach aims to reduce data movement between sensory and computing units, minimizing the need for data transfer and conversion at the sensor-processor interface. Here, an optical neuromorphic synaptic (ONS) device is demonstrated by homogeneously integrating optical-sensing and synaptic functionalities into a unified material platform, constructed exclusively by all-inorganic perovskite CsPbBr3 quantum dots (QDs). The dual functionality of each unit within the ONS device, which can be operated as either an optical sensor or a synaptic device depending on applied electrical polarity, provides significant advantages over previous heterogeneous integration methods, particularly regarding material selection, structural compatibility, and devicefabrication complexity. The ONS device exhibits distinct wavelength responses essential for emulating colored image recognition capability inherent in the human visual system. Additionally, the seamless integration of electronics and photonics within a unified material system establishes a novel paradigm for optical retrieval, enabling real-time perception of the encoded status of the ONS device. These findings represent substantial advancements in near-sensor computing platforms and open a new horizon for all-inorganic perovskite optoelectronic technologies.

Nonlinear optical properties of lead halide perovskite CsPbBr3 for ultrafast pulse generation

Halide perovskites have attracted much attention in the field of nonlinear optics due to their strong quantum constraint, obvious exciton effect, and structural diversity. In this paper, lead halide perovskite CsPbBr3 nanocrystals were synthesized with a size of 50–100 nm. The prepared CsPbBr3 nanocrystals were deposited on the conical microfibers so that the nonlinear optical absorption features can be obtained. Based on a balanced twin-detector system, the modulation depth of the prepared CsPbBr3 nanocrystals was determined as 9.2% and 7.2% at 1 µm and 1.5 µm, respectively. When the CsPbBr3 saturable absorber (SA) was inserted into the Yb-doped fiber laser (YDFL), a stable noise-like pulse (NLP) mode-locking operation was obtained at a central wavelength of 1034 nm with a pulse duration of 415 fs. In the negative dispersive Er-doped fiber laser (EDFL), both the bound-state mode-locking operation with a pulse width of 971 fs and the conventional soliton mode-locking with a pulse width of 799 fs can be achieved at 1531 nm for the first time. These findings not only pave the way for a deeper understanding of the nonlinear optical properties in CsPbBr3 nanocrystals but also provide a solid platform for further exploration of applications in ultrafast photonics.

Enhanced Performance and Stability of CsPbBr3 Perovskite Solar Cells Using Trioctylphosphine Oxide Additive.

This study investigates the application of trioctylphosphine oxide (TOPO) and triphenylphosphine oxide (TPPO) as an additive to enhance the performance of all-inorganic CsPbBr3 perovskite solar cells (PSCs). The addition of TOPO and TPPO passivates surface defects, increases grain size, and reduces surface trap states, leading to better light absorption and accelerated carrier transport. These modifications lead to an optimized energy level distribution, resulting in a significant increase in power conversion efficiency from 5.14 to 9.21% with TOPO and from 5.14% to 7.28% with TPPO. Furthermore, the long alkyl chains in TOPO provide effective isolation from air and water, significantly enhancing device stability for over 2400 h without packaging. The findings demonstrate that oxygen phosphine additives with long alkane chains are more effective in improving PSCs than those with aromatic hydrocarbons, offering new insights for the use of passivators in perovskite solar cells.

Real-time three-dimensional monitoring and analysis of perovskite solar cell using short wavelength infrared digital holography

The quality and crystallization process of all-inorganic perovskite films play a crucial role in the performance of solar cells. However, traditional detection methods lack three-dimensional depth information and real-time capabilities, hindered by strong visible light absorption, posing challenges to research. Here, a simple digital holography technique is proposed that offers real-time, nondestructive, three-dimensional phase imaging with low absorption characteristics in the short-wave infrared range. The use of short-wave infrared reduces the negative impact of visible light and vibrations in the environment on detection accuracy, while being nearly non-absorbing. The proposed method operates at a speed of 15 Hz, combining a lensless vertical structure, holographic reconstruction algorithm, and phase unwrapping algorithm to achieve real-time three-dimensional observation without image distortion and with low noise of the crystallization process of CsPbBr3 perovskite quantum dots (PQDs)/ethylene-vinyl acetate solution, which crystallizes in 39 s. Subsequently, employing minimum bounding rectangle, field stitching, intensity registration, and sub-pixel level calibration algorithms, real-time characterization is performed on the large-sized droplet of polymethyl methacrylate-matrix-encapsulated CsPbBr3 perovskite quantum dots, which has a crystallization time of 1285 s, without being limited by the field of view. Finally, using this system, the surface quality of the film is assessed, revealing fluctuations at the edge and fabrication defects of the perovskite film. Experimental results demonstrate the potential of short-wave infrared digital holography in enhancing the film formation process and quality inspection. By leveraging this technology, advancements in the development of high-performance all-inorganic perovskite solar cells can be fostered, optimizing global energy output.

3D Printed Ultra‐Fast Plastic Scintillators Based on Perovskite‐Photocurable Polymer Composite

AbstractAdditive manufacturing technology is exploited for the first time to build a complex geometry scintillator using a thermosetting photocurable resin filled by lead halide perovskite as an active material. To this aim, an innovative nanocomposite is developed based on Cs4PbBr6 perovskite powders as fillers and photocurable resin as matrix, adopting stereolithography as a manufacturing process. The use of high‐Z lead‐based perovskite filler is needed for the detection of ionizing radiation and the conversion into visible light, while the polymer matrix provides 3D printability. On the one hand, the inclusion of the perovskite‐based filler in the photocurable resin does not affect the rheological behavior and photocuring properties of the polymer matrix, making the composite suitable for 3D printing by stereolithography. On the other hand, the presence of the polymer does not affect the emission properties of the perovskite leading to the development of a fast response scintillator with significantly improved environmental stability. This work opens the avenue to the development of a completely new class of plastic scintillating materials.

Ion Migration Enhances the Performance of Perovskite CsPbBr3 γ‐Ray Detectors

AbstractUncontrolled ion migration is well‐known in perovskite‐based semiconductor devices. Here, it is shown that instead of being detrimental, ion migration can be used to enhance the performance of perovskite CsPbBr3 semiconductor gamma‐ray detectors. Through the deliberate application of electrical biasing, ion migration is actively controlled to modify the metal‐CsPbBr3 interface barrier height in devices with asymmetric electrodes. Ion migration plays a pivotal role in reducing bulk defects, as evidenced by the contact potential difference measurement, thermally stimulated current spectroscopy and photoluminescence measurements. The evidence suggests that biasing‐induced ion migration in CsPbBr3 results in a reduction in electron traps and significant detector improvement. As biasing at elevated temperatures expedites ion migration, preconditioning the CsPbBr3 crystals through reverse biasing is a promising strategy for enhancing their energy‐resolving performance.

Machine learning-driven fluorescent sensor array using aqueous CsPbBr3 perovskite quantum dots for rapid detection and sterilization of foodborne pathogens

With the growing global concern over food safety, the rapid detection and disinfection of foodborne pathogens have become critical in public health. This study presents a novel machine learning-driven fluorescent sensor array utilizing aqueous CsPbBr3 perovskite quantum dots (PQDs) for the rapid identification and eradication of foodborne pathogens. The relative signal intensity changes (ΔRGB) generated by the sensor array were analyzed using the machine learning algorithm—Support Vector Machine (SVM). The study achieved the identification and recognition of five pathogens and their mixtures within a concentration range of 1.0 × 103 to 1.0 × 107 CFU/mL with an accuracy rate of 100 %, and the limits of detection (LOD) for the pathogens were found to be low. Additionally, the array also showed excellent performance in the identification of pathogens in tap water, achieving an accuracy rate of 100 %. Furthermore, the fluorescent sensor array was capable of inactivating the pathogens with an efficiency of over 99 % within 30 min post-detection. This development provides an efficient and reliable tool for the field of food safety detection.

Atomic-Scale Insights into Surface Instability in Halide Perovskites.

The pathway of surface structure evolution plays a vital role in determining the stability of the halide perovskites. Understanding the mechanism of surface instability and how external stimuli interact with the surface is essential for developing strategies to mitigate the degradation of halide perovskites. Here, we directly observed structural evolutions on the surface of CsPbBr3 via an integrated differential phase contrast scanning transmission electron microscope. We find that surface degradation, different from bulk decomposition, follows a layer-by-layer pathway in the CsPbBr3 perovskite. This layer-by-layer decomposition method further facilitated a coating strategy to mitigate the degradation via preserving the integrity of the surface layer, as verified through in situ methods. Thus, we have achieved the improved stability of perovskites and as-fabricated light-emitting diodes. These findings advance the fundamental understanding on the mechanism of surface instability and effectiveness of coating, thus providing guidance for future study of surface protection toward stable optoelectronic devices.

Pressure-induced structural and electronic properties of inorganic halide perovskite CsPbBr3

In this paper, Density Functional Theory (DFT) based on first principles is used to study the influence of pressure on the structural and electronic properties of the cubic and orthorhombic phases of halogen perovskite CsPbBr3. We observe that the lattice constant of the cubic phase shows a monotonically decreasing trend in a wide pressure range, while the Pb–Br irregular octahedron of the orthorhombic phase rotates under pressure and distorts at 65.5 GPa, 67 GPa, 69.5 GPa, and 70 GPa pressure points, respectively. Moreover, the pressure has a good adjustment effect on the band gap of the cubic and orthorhombic phases. The band gap of the orthorhombic phase changes between the direct band gap and the indirect band gap under pressure. The charge difference density and density of states are calculated to study the type of bonds between internal atoms and the effect of pressure on the distribution of orbital electrons. The study of the Crystal Orbital Hamilton Populations and lattice energy of the electron cloud shows that the pressure has a significant adjustment effect on the strength of the Pb–Br covalent bond and the Cs–Br ionic bond. These results provide a comprehensive reference and guidance for the further research and application of perovskite material pressure engineering.

Photoluminescence Properties of Lead Halide Perovskite Nanocrystals Revealed By Single-Dot Spectroscopy

Lead halide perovskites have attracted much attention as a new class of optoelectronic device materials because of their outstanding optical, electronic, and transport properties [1,2]. In addition, halide perovskite nanocrystals (NCs), which can be synthesized by simple chemical methods, show near unity photoluminescence (PL) quantum yields, with keeping the superior optoelectronic properties of their bulk counterparts [3,4]. Because of the small orbital degeneracy of the band edge, PL properties of halide perovskite NCs are governed by the formation and recombination dynamics of excitons, trions, and biexcitons [5,6]. Since individual NCs show narrow PL linewidths at low temperatures, multipeak PL structures appear and their origins are an exciton, a trion, and a biexciton. Single dot spectroscopy is a powerful tool to investigate the exciton–exciton, exciton–electron, and exciton–phonon interactions in perovskite NCs.Here, we prepared three types of perovskite NC samples, CsPbBr3, CsPbI3 and FAPbBr3, and studied their PL spectra of single NCs at room temperature and low temperatures. At room temperature, all NCs show PL blinking, and nonradiative Auger recombination of trions and biexcitons determines the PL dynamics [7–10]. At low temperatures, all NC samples show strong PL, and several PL peaks originating a trion, a biexciton, and longitudinal-optical-phonon side bands of an exciton were clearly observed in the low energy side of the strong exciton peak [11–13]. The PL spectra of all samples were very similar to each other. We clarified the NC size dependence of the trion and biexciton binding energies and the Huang–Rhys (HR) factors, i.e., the strength of the exciton–phonon coupling, in three different perovskites. The positive binding energies of trions and biexcitons show the attractive exciton–exciton Coulomb interactions in the perovskite NCs, and these binding energies increase with decreasing NC size [11,13]. In addition, these size dependences follow a universal scaling curve regardless of composition when the binding energy and the NC size are normalized by the bulk exciton binding energy and the exciton Bohr radius, respectively [13]. The PL linewidths of all inorganic CsPbBr3 and CsPbI3 NCs were narrower than those of organic-inorganic hybrid FAPbBr3 NCs, suggesting the strong exciton–phonon coupling with large organic cation. In FAPbBr3 NCs, the size dependence of the HR factors is similar to that of the Urbach energy [10,11]. In all samples, the LO-phonon energies are independent of the NC size, while the HR factors increase as the NC size decreases [11,12]. Our findings provide new insights into understanding of the optical responses of halide perovskite NCs and the design of the single photon sources.Part of this work was supported by JST-CREST (JPMJCR21B4) and JSPS KAKENHI (JP19H05465).

(Invited) Self-Recovery of Photodegraded CsPbBr3 Perovskite Nanocrystals and Problems By Irreversible Damage

CsPbBr3 perovskite nanocrystals (NCs) synthesized by a typical hot injection method are adsorbed with surface modifiers. The authors have investigated photodegradation and self-recovery phenomena due to photo-induced desorption by excitation light irradiation and re-adsorption of the surface modifiers in the dark, respectively [1-4]. These phenomena occurred when a dry solid sample of NCs was placed in a sample holder covered with a glass plate to shut out the atmosphere. On the other hand, the dried NCs exposed to the air did not show the self-recovery after photodegradation. This was due to irreversible degradation caused by surface oxidation by atmospheric oxygen. When the dried NCs were covered with a resin film instead of a glass plate, the resin with lower gas barrier properties did not prevent oxidation. However, the use of a resin with higher gas barrier properties confirmed the occurrence of photodegradation and subsequent self-recovery. The authors will present recent results including experiments on nanocomposite films of the NCs dispersed in resin.References K. Kidokoro, Y. Iso, T. Isobe, J. Mater. Chem. C, 7, 8546 (2019).K. Miyashita, K. Kidokoro, Y. Iso, T. Isobe, ACS Appl. Nano Mater., 4, 12600 (2021).I. Enomoto, Y. Iso, T. Isobe, J. Mater. Chem. C, 10, 102 (2021).K. Kano, Y. Iso, T. Isobe, ECS J. Solid State Sci. Technol., 12, 056003 (2023). Figure 1