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Halide perovskite nanocrystals are at the forefront of materials research due to their remarkable optoelectronic properties and versatile applications. While their lattice structure and optical properties have been extensively investigated for the structure–property correlation, their lattice dynamics, the physical link between the lattice structure and optoelectronic properties, has been much less visited. We report the evolution of structural dynamics of a series of cesium lead halide perovskite nanocrystals whose size and morphology are systematically varied by synthesis temperature. Low-frequency Raman spectroscopy uncovers the nanocrystals' structural dynamics, including a relaxational spectral continuum from ligand librations and a phonon spectrum evolving with nanocrystal size. As the size of nanocrystals increases, their phonon spectrum becomes more intense, and their spectral weights redistribute with new first- and second-order modes being activated. The linewidth of the observed phonon modes generally broadens as the nanocrystal grows larger, an interesting deviation from the established phonon confinement model. We suggest that strong confinement and truncation of the lattice and ligands anchoring on the surface might lead to pinning of the lattice dynamics at nanoscale. These findings offer new insights into the bulk–nano-transition in halide perovskite soft semiconductors. [ABSTRACT FROM AUTHOR]

Over the past decade, the certified power conversion efficiency of perovskite solar cells (PSCs) has increased to 26.1%. However, phase instability originating from lattice strains, has limited their commercialization. Strains will inevitably be generated during the PSC fabrication and service process due to the "soft lattice" nature of halide perovskites. In particular, flexible PSCs are subjected to not only mechanical tensile and compressive loads, but also suffer from thermal stresses. In this study, strain-induced changes in the phase stability and the corresponding optoelectronic properties of CsPbI3−xBrx (CsPbI3, CsPbBr3, and CsPbI2Br) systems under tensile and compressive stresses were investigated using first-principles calculations. The results showed that compressive stresses reduce the bandgap value and increase the light absorption coefficient; thus, the optoelectronic performance is improved, whereas the light absorption coefficient decreases regardless of how the bandgap changes under tensile stresses. Moreover, under the same stress, the tensile strain value was twice that of the compressive strain, and the critical value of the transition from the cubic to tetragonal phase was lower, indicating that phase stability was worse under tensile stresses. Therefore, during the fabrication of PSCs, the tensile stress state should be adjusted to the compressive stress state, which is favorable for enhancing PSCs photovoltaic performance and phase stability. The results not only provide direct evidence of tensile and compressive strains influencing the phase stability and optoelectronic property changes in halide perovskites, but also highlight lattice-strain tailoring for the composition design, process optimization, and interface engineering of efficient and stable PSCs. [ABSTRACT FROM AUTHOR]

An exciton–polariton condensate is a hybrid light–matter state in the quantum fluid phase. The photonic component endows it with characters of spin, as represented by circular polarization. Spin-polarization can form stochastically for quasi-equilibrium exciton–polariton condensates at parallel momentum vector k|| ∼ 0 from bifurcation or deterministically for propagating condensates at k|| > 0 from the optical spin-Hall effect (OSHE). Here, we report deterministic spin-polarization in exciton–polariton condensates at k|| ∼ 0 in microcavities containing methylammonium lead bromide perovskite (CH3NH3PbBr3) single crystals under non-resonant and linearly polarized excitation. We observe two energetically split condensates with opposite circular polarizations and attribute this observation to the presence of strong birefringence, which introduces a large OSHE at k|| ∼ 0 and pins the condensates in a particular spin state. Such spin-polarized exciton–polariton condensates may serve not only as circularly polarized laser sources but also as effective alternatives to ultracold atom Bose–Einstein condensates in quantum simulators of many-body spin–orbit coupling processes. [ABSTRACT FROM AUTHOR]

This study explored the interplay between the ligand–surface chemistry of colloidal CsPbBr3 nanowires (NWs) and their optical properties. The ligand equilibrium was probed using nuclear magnetic resonance spectroscopy, and by perturbing the equilibrium via dilution, the gradual removal of ligands from the CsPbBr3 surface was observed. This removal was correlated with an increase in the surface defect density, as suggested by a broadening of the photoluminescence (PL) spectrum, a decrease in the PL quantum yield (PLQY), and quenching of the PL decay. These results highlight similar surface binding between the traditional CsPbBr3 quantum dots and our NWs, thereby expanding the scope of well-established ligand chemistry to a relatively unexplored nanocrystal morphology. By controlling the dilution factor, it was revealed that CsPbBr3 NWs achieve a PLQY of 72% ± 2% and a relatively long average PL lifetime of 400 ± 10 ns, without relying on additional surface passivation techniques, such as ligand exchange. [ABSTRACT FROM AUTHOR]

Lead halide perovskite nanocrystals (NCs) have superior luminescence properties compared to classical semiconductor NCs and they are considered promising materials for next-generation emitters. In this work, we measured the size and temperature dependence of the luminescence decay curve in CsPbBr 3 NCs. To reproduce the experimental results, a simple model including one and two-phonon transitions between the exciton fine structures is introduced. It is found that the temperature dependence of the decay rates in small NCs is better reproduced by the two-phonon model rather than by the one-phonon model. However, the one-phonon process becomes more important for large NCs as the bright-dark splitting decreases. [ABSTRACT FROM AUTHOR]

Chiral hybrid lead halide perovskites show interesting chiral optoelectronic properties. The extent of chirality is often estimated by their circular dichroism (CD) response. Here, we show that the CD data depend strongly on film morphology. Four of the six chiral hybrid lead halide films prepared, 2D (R- and S-MBA)2PbI4 and 1D (R- and S-MBA)PbI3 (MBA: methylbenzylammonium), form homogenous non-textured films and show an isotropic CD signal. In contrast, the other two samples, 1D (R- and S-MBA)PbBr3, form textured films, showing uncorrelated CD signals from different parts of the film. Therefore, the role of film morphology needs to be verified before designing and comparing the chiroptic and chiral optoelectronic properties of hybrid perovskites. [ABSTRACT FROM AUTHOR]

Halide perovskite, Bridgman grown single crystals have shown excellent performance for high energy radiation detectors. CsPbBr3 perovskite detectors with 1.4% energy resolution have been demonstrated. These detectors demonstrate a wide range of operations from −2 to 70 °C. Semiconductor hard radiation detectors have been used for applications in defense, medicine, and bioelectronics. In most of these applications, there is a need for the detectors to operate at room temperature and above. Previous hard radiation detector devices have used the material cadmium zinc telluride for room temperature operation [Luke et al., IEEE Trans. Nucl. Sci. 48, 282 (2001)]. There are now other semiconductors that show considerable promise. These include the halide perovskite compound semiconductors with a formula CsPbX3, where X = Cl, Br, I [Liu et al., Proc. SPIE 8852, 88520A (2013); Peters et al., J. Lumin. 243, 118661 (2022)]. These materials are also being developed for other device applications, including light-emitting diodes, lasers, solar cells, and photodetectors. It is claimed that these semiconductors are defect-tolerant, although the reason for this behavior is not well understood. Thermally stimulated current spectroscopy was used to detect electron traps in these materials to improve their performance. The halide compound cesium lead bromide has a bandgap of 2.25 eV, which makes it suitable for room temperature operation and above. They also have high permittivity. These halide perovskite semiconductors have shown room temperature detector device performance. Recently, we demonstrated hard radiation detectors using CsPbBr3 as the device platform. The detectors had 1.4% energy resolution for high-energy γ rays [He et al., Nat. Photonics 15, 36 (2021)]. The detectors demonstrate a wide temperature region from −2 to 70 °C for stable operations. [ABSTRACT FROM AUTHOR]

Herein, we report a novel and powerful approach developed to lower the manufacturing costs of PSCs and make them powerful and cost-effective technology through identifying more efficient and low-cost dopant-free hole-transport materials (HTMs) for PSCs by avoiding the shotgun approach of synthesizing hundreds or thousands of HTMs, fabricate devices and characterize them to identify the best performing candidate(s). With these in mind, the primary objective of this study is to develop a machine learning model extracted from automated-quantitative structure–property relationship (autoQSPR) models that could accurately predict various photovoltaic properties, including power conversion efficiency (PCE), open-circuit photovoltage (VOC), and short-circuit photocurrent (JSC), of dopant-free HTM-based PSCs. High-efficacy AutoQSPR models capable of accurately predicting photovoltaic properties were developed by considering experimental photovoltaic property data sets from dopant-free HTMs used in the fabrication of PSCs with different architectures, e.g., conventional (n–i–p) and inverted (p–i–n), which are fabricated using methyl ammonium lead halides (MALHs) or mixed cation lead halides, were used to develop high efficacy autoQSPR models capable of accurate predictions of photovoltaic properties. The Schrodinger Suite was utilized to build autoQSPR models to predict PCE, VOC, and JSC utilizing different kinds of molecular descriptors such as 2D binary fingerprints, one dimensional (1D), two dimensional (2D), and three dimensional (3D). Notably, 2D binary fingerprint descriptors generate models that outperform 1D, 2D, and 3D molecular descriptors calculated using the well-known PaDEL calculator. The developed autoQSPR models were improved when the PSC configurations were considered and a significant predictive ability (test set Q2 > 0.5) was achieved for all autoQSPR models that involved the use of 2D binary fingerprint descriptors. The model confidence was validated by the utilization of dopant-free HTMs that were not present in the original dataset used to build the models. Furthermore, the most efficient models were used to propose potential HTM candidates to benefit the scientific community and scholars. [ABSTRACT FROM AUTHOR]

A solid-state synthesis of blue-emitting lead halide nanoclusters has been demonstrated for the first time. The solid-state grinding synthesis provides a facile method to produce highly confined lead bromide clusters under ambient conditions. Both CH3NH3PbBr3 perovskite magic-sized clusters and lead halide molecular clusters have been produced, as confirmed by comparison to those synthesized using a ligand-assisted reprecipitation method in terms of electronic absorption, photoluminescence, and solid state characterization. [ABSTRACT FROM AUTHOR]

Most polymetallic hybrid metal halides are assumed to show a homogenous distribution of the metal ions in the bulk. Herein, we demonstrate a core–shell model for the hybrid lead halide [(C6H18N3)2·Pb2Br10] (C6H18N3 = 2-(piperazin-1-yl)ethan-1-aminium) coated with a manganese bromide layer. This model can explain the different photoemission of this composite material, and provides new insights on the investigation of polymetallic low-dimensional organic metal halides. [ABSTRACT FROM AUTHOR]

Chalcogenide perovskites have garnered increasing attention as stable, non‐toxic alternatives to lead halide perovskites. However, their conventional synthesis at high temperatures (>1000 °C) has hindered widespread adoption. Recent studies have developed low‐to‐moderate temperature synthesis methods (<600 °C) using reactive precursors, yet a comprehensive understanding of the pivotal factors affecting reproducibility and repeatability remains elusive. This study delineates the critical factors in the low‐temperature synthesis of BaMS3 (M═Zr, Hf, Ti) compounds and presents a generalized framework. Innovative approaches are developed for synthesizing BaMS3 compounds using this framework involving organometallics for solution deposition. The molecular precursor routes, employing metal acetylacetonates to generate soluble metal–sulfur bonded complexes and metal–organic compounds to produce soluble metal‐thiolate, metal‐isothiocyanate, and metal‐trithiocarbonate species, are demonstrated to yield carbon‐free BaMS3. These methods have achieved the most contiguous films of BaZrS3 and BaHfS3 using solution deposition to date. Furthermore, a hybrid solution processing method involving stacking sputter‐deposited Zr and solution‐deposited BaS layers is employed to synthesize a contiguous, oxygen‐free BaZrS3 film. The diffuse reflectance measurements indicate a direct bandgap of ≈ 1.85 eV for the BaZrS3 films and ≈ 2.1 eV for the BaHfS3 film under investigation. [ABSTRACT FROM AUTHOR]

All‐inorganic cesium lead halide perovskites (CsPbX3, with X = I, Br, Cl) are of great interest for light‐emitting diodes and lasers, as they promise improved thermal stability compared to their organic–inorganic analogues. However, among this family of materials, CsPbI3 shows a detrimental phase instability that causes the perovskite to convert to a thermodynamically preferred non‐perovskite phase (yellow phase) at room temperature. In fact, reports on lasers using thin films of CsPbI3 as gain medium are missing, as of yet. Here, the first distributed feedback (DFB) lasers based on CsPbI3 thin films are presented with a resonator directly patterned into the perovskite by thermal nanoimprint. This breakthrough is unlocked by the additive polyvinyl pyrrolidone (PVP), that affords the formation of perovskite layers consisting of phase stable γ‐CsPbI3 nanocrystals, that are even preserved during thermal imprint at 170 °C. The DFB lasers show a low lasing threshold of 45 µJ cm−2 at room temperature under optical pumping and a tunable emission in the deep red spectral region between 714.1 to 723.4 nm. It is anticipated that the findings of this work will have a broad relevance for future electrically driven perovskite lasers and for light‐emitting diodes based on CsPbI3 as active medium. [ABSTRACT FROM AUTHOR]

Perovskite‐inspired materials (PIMs) are potential alternatives to lead halide perovskites, as they not only inherit the benign optoelectronic properties but also diminish the stability and toxicity issues of lead halide perovskites. As a newly discovered PIM, Cu2AgBiI6 has exhibited promising potential for photovoltaic applications. However, studies on its fundamental properties related to photovoltaic performance are scarce, particularly from a theoretical perspective. Herein, the effective lifetime of nonequilibrium carriers (photo‐excited charge carriers) is systematically investigated, a critical property affecting the photovoltaic performance of Cu2AgBiI6, based on the nonadiabatic molecular dynamics simulations. It is found that under the standard solar spectrum illumination, the dominant recombination mechanism affecting the effective lifetime can be band‐to‐band nonradiative decay, band‐to‐band radiative decay, or Shockey–Read–Hall defect‐assisted decay. The specific mechanism is highly dependent on the radiative recombination coefficient and the density of defect recombination levels. The effective lifetime can vary from 0.1 ms to 10 ns. When considering different illumination conditions (generation rates), Auger decay can also become the dominant recombination mechanism, with the effective lifetime varying from 0.1 s to 0.1 ns. These findings can be vital for further experimental researches aimed at enhancing the power conversion efficiency of Cu2AgBiI6‐based solar devices. [ABSTRACT FROM AUTHOR]

The material family halide perovskites has been critical in recent room-temperature radiation detection semiconductor research. Cesium lead bromide (CsPbBr3) is a halide perovskite that exhibits characteristics of a semiconductor that would be suitable for applications in various fields. In this paper, we report on the correlations between material purification and crystal material properties. Crystal boules of CsPbX3 (where X = Cl, Br, I, or mixed) were grown with the Bridgman growth method. We describe in great detail the fabrication techniques used to prepare sample surfaces for contact deposition and sample testing. Current–voltage measurements, UV–Vis and photocurrent spectroscopy, as well as photoluminescence measurements, were carried out for material characterization. Bulk resistivity values of up to 3.0 × 109 Ω∙cm and surface resistivity values of 1.3 × 1011 Ω/□ indicate that the material can be used for low-noise semiconductor detector applications. Preliminary radiation detectors were fabricated, and using photocurrent measurements we have estimated a value of the mobility–lifetime product for holes (μτ)h of 2.8 × 10−5 cm2/V. The results from the sample testing can shed light on ways to improve the crystal properties for future work, not only for CsPbX3 but also other halide perovskites. [ABSTRACT FROM AUTHOR]

Structural disorder is common in metal‐halide perovskites and important for understanding the functional properties of these materials. First‐principles methods can address structure variation on the atomistic scale, but they are often limited by the lack of structure‐sampling schemes required to characterize the disorder. Herein, structural disorder in the benchmark inorganic halide perovskites CsPbI3 and CsPbBr3 is computationally studied in terms of the three octahedral‐tilting angles. The subsequent variations in energetics and properties are described by 3D potential‐energy surfaces (PESs) and property landscapes, delivered by Bayesian optimization as implemented in the Bayesian optimization structure search code sampling density functional theory (DFT) calculations. The rapid convergence of the PES with about 200 DFT data points in 3D searches demonstrates the power of active learning and strategic sampling with Bayesian optimization. Further analysis indicates that disorder grows with increasing temperature and reveals that the material bandgap at finite temperatures is a statistical mean over disordered structures. [ABSTRACT FROM AUTHOR]

Lead halide perovskite exhibits great prospects in next‐generation display. However, single‐cation inorganic perovskite nanocrystals (NCs) still suffer from offset gamut coordinates determined by bandgap, short operating life, and low‐efficiency in light‐emitting diodes (LEDs), on account of the limitations in lattice stability and defect levels. Here, a thermodynamic co‐competition strategy is proposed for fabricating Cs1−xFAxPbBr3 NCs, which reveals the spatial distribution of A‐site cations and the improvement of photoelectronic performance. This strategy achieves precise control of NCs in the pure‐green range with an accuracy of sub‐nanometer, further promotes the comprehensively filling‐suppressing effect of incongruous lattice and surface defects. Finally, the high‐precision adjusting in electroluminescence is achieved, and the champion device achieves a CIE coordinate of (0.121, 0.788), meeting the pure‐green range in BT.2020. Simultaneously, the PeLED demonstrates an EQE exceeding 20% with superior stability, accompanied by 20‐fold improvement in lifetime, indicating tremendous potential in next‐generation display. [ABSTRACT FROM AUTHOR]

In the pursuit of efficient optoelectronics devices, hybrid lead halide perovskite quantum dots (PQDs) have emerged as highly promising semiconductor materials due to their intriguing properties. While these materials have been used in many applications, the fundamental understanding of their behavior remains relatively unexplored, especially for the mixed halide perovskite samples. To facilitate the advancement of PQD technologies for commercial applications, it is essential to gain insights into the role of ion migration. This study delves into the fundamental aspects of ion migration in halide perovskite nanocrystals. Porous electrodes for supercapacitor application were fabricated using CsPbBr3–xIx (x=0,1,2) nanocrystals prepared via the ligand‐assisted re‐precipitation (LARP) method. Three‐electrode electrochemical measurements and several other characterizations were conducted under dark conditions to evaluate device performance and elucidate the impact of mixed halides on device kinetics and stability. X‐ray photoelectron spectroscopy before and after the electrochemical measurement reveals intriguing findings. Notably, the analysis uncovered the phase segregation in the metal halide perovskite nanocrystals with particular emphasis on CsPbBr2I due to its distinctive mixed‐halide behavior. The specific capacitance increases with the increasing cycles. Interestingly, as the iodide content increases, there is no selective halide expulsion as the structure collapses rapidly. [ABSTRACT FROM AUTHOR]

Perovskite‐inspired materials (PIMs) are potential alternatives to lead halide perovskites, as they not only inherit the benign optoelectronic properties but also diminish the stability and toxicity issues of lead halide perovskites. As a newly discovered PIM, Cu2AgBiI6 has exhibited promising potential for photovoltaic applications. However, studies on its fundamental properties related to photovoltaic performance are scarce, particularly from a theoretical perspective. Herein, the effective lifetime of nonequilibrium carriers (photo‐excited charge carriers) is systematically investigated, a critical property affecting the photovoltaic performance of Cu2AgBiI6, based on the nonadiabatic molecular dynamics simulations. It is found that under the standard solar spectrum illumination, the dominant recombination mechanism affecting the effective lifetime can be band‐to‐band nonradiative decay, band‐to‐band radiative decay, or Shockey–Read–Hall defect‐assisted decay. The specific mechanism is highly dependent on the radiative recombination coefficient and the density of defect recombination levels. The effective lifetime can vary from 0.1 ms to 10 ns. When considering different illumination conditions (generation rates), Auger decay can also become the dominant recombination mechanism, with the effective lifetime varying from 0.1 s to 0.1 ns. These findings can be vital for further experimental researches aimed at enhancing the power conversion efficiency of Cu2AgBiI6‐based solar devices. [ABSTRACT FROM AUTHOR]

Low-dimensional organic–inorganic hybrid lead halide perovskites have attracted much interest in solid-state lighting and displays, but the toxicity and instability of lead halide are obstacles to their industrial applications, which must be overcome. As an alternative, Cu(I)-based hybrid metal halides have emerged as a new type of luminescent material owing to their diversified structure, adjustable luminescence, low toxicity and low cost. Herein, we report three one-dimensional (1D) hybrid Cu(I)-based halides with the general formula ACu2Br4 (A = [(Me)4-Pipz]2+ and [BuDA]2+ and [TMEDA]2+). These 1D hybrid Cu(I) halides display stable broadband blue emission with maximum emission peaks in the range of 445–474 nm and the highest photoluminescence quantum yield of 37.8%. Furthermore, in-depth experimental and theoretical investigations revealed that the broadband blue emissions originate from the radiative recombination of self-trapped excitons. Most importantly, there is no structural degradation and attenuation of emission intensity even after continuously soaking these halides in water for at least two months, demonstrating their ultra-high anti-water stability. Hirshfeld surface analysis shows that a large number of weak hydrogen bonds can protect the inorganic skeleton from degradation due to water. This work provides a new strategy for the design of water-stable Cu(I)-based halides with efficient blue emission and wide potential applications in humid environments. [ABSTRACT FROM AUTHOR]

Chiral organic–inorganic hybrid lead halides have recently attracted great attention due to their unique chirality and diverse functional properties. However, they suffer from highly toxic lead, while lead‐free chiral hybrid metal halides especially those with phase transitions remain sparse. Here, we report a new lead‐free chiral metal halide crystal [R‐3‐fluoropiperidinium]2SbCl5 ([R‐3‐FPP]2SbCl5), which crystalizes in chiral P212121 space group at 293 K and consists of chiral [3‐FPP]+ cations and one‐dimensional [SbCl5]n2− zigzag chains of corner‐sharing SbCl6 octahedrons. Notably, [R‐3‐FPP]2SbCl5 undergoes an above room temperature phase transition at 313 K, which can be attributed to the order‐disorder transition of both the organic [R‐3‐FPP]+ cation and inorganic [SbCl5]2− anions. In addition, [R‐3‐FPP]2SbCl5 also shows a broad band gap of 3.21 eV. This work promotes the exploration of chiral lead‐free hybrid lead halides with phase transitions. [ABSTRACT FROM AUTHOR]

Two‐dimensional lead halide perovskites (2D HPs) represent as an emerging class of materials given their tunable optoelectronic properties and long‐term stability in perovskite solar cells. However, the ever‐growing field of optoelectronic devices using 2D HPs requires fundamental understanding of the influence of the spacer on the physiochemical properties and stability of perovskites as well as establish which cation properties are closely related to suppress the halogen ion mobility. This study focuses on investigating the influence of organic spacers with intrinsic properties (e.g., rigidity and flexibility, special groups) and variations of material dimensions on the stability of halogen ions and inorganic frameworks in 2D HPs. It is found that the perovskite structure composed of rigidity molecules owns better stability of halogen ion and inorganic framework than that of flexible molecules. The stability of ions exhibits a negative correlation with the dimensions of perovskite. More importantly, a simple descriptor for measuring the stability of halogen ions in 2D HPs is constructed. By causal discovery algorithms with more physical and chemical significance, the Kappa shape index, number of rotatable bonds, and aromatic carbocycles in organic spacers are identified as causal and important features for the stability of halogen ions in 2D HPs. [ABSTRACT FROM AUTHOR]

Mixed lead halide perovskites have shown remarkable performance in photovoltaic and optoelectronic applications. Pure hybrid halide perovskites undergo clear phase transitions, however, the phase transitions in mixed perovskites are less studied. We present a contrasting behavior of the phase transition dynamics of MAPbBr 3- x Cl x (MA = CH 3 NH 3 +) mixed halide perovskites compared to the pure MAPbX 3 (X = Cl, Br) counterparts, which typically exhibit order-disorder phase transitions through a series of distinct structural phases. We have employed several spectroscopic techniques including temperature-dependent PXRD, Raman, dielectric and Brillouin spectroscopy. The results demonstrate that the mixed halide perovskite MAPbBr 1.5 Cl 1.5 does not undergo any structural phase transition typically observed in pure halide perovskites. We observed signatures of glassy behavior in mixed compositions of this system. In addition, we also explored the effects of replacing A-site cation on the phase transition behaviors. The results contribute to the understanding of phase transition mechanisms in perovskites and have implications for their stability and optoelectronic properties. [ABSTRACT FROM AUTHOR]

Lead halide perovskite (LHP) have gained considerable research attention for their numerous photoelectric applications attributed to their ease of processability and distinctive photoelectric properties. A‐site cation engineering provides an effective solution to optimize the bandgap further, enhance stability, and improve the photoelectric properties of LHP materials. In this review, an in‐depth examination of the progress achieved in the field of A‐site cation engineering on the structure, properties, synthesis methods, and photoelectric applications of LHP is presented. It is discussed how A‐site cations can change the crystal structure and improve the crystal quality, and how the A‐site cation regulates the bandgap, enhances stability, and promotes effective charge transport. Further, synthesis strategy is presented to regulate the A‐site cation. Subsequently, the applications of A‐site cation‐regulated LHP materials in solar cells, light‐emitting diodes, photodetectors, and lasers are introduced. Finally, challenges that must be overcome to further improve the properties and stability of LHP materials via A‐site cation engineering are highlighted. [ABSTRACT FROM AUTHOR]

The engineering of tunable photoluminescence (PL) in single materials with a full‐spectrum emission represents a highly coveted objective but poses a formidable challenge. In this context, the realization of near‐full‐spectrum PL emission, spanning the visible light range from 424 to 620 nm, in a single‐component two‐dimensional (2D) hybrid lead halide perovskite, (ETA)2PbBr4 (ETA+=(HO)(CH2)2NH3+), is reported, achieved through high‐pressure treatment. A pressure‐induced phase transition occurs upon compression, transforming the crystal structure from an orthorhombic phase under ambient conditions to a monoclinic structure at high pressure. This phase transition driven by the adaptive and dynamic configuration changes of organic amine cations enables an effective and continuous narrowing of the band gap in this halide crystal. The hydrogen bonding interactions between inorganic layers and organic amine cations (N−H⋅⋅⋅Br and O−H⋅⋅⋅Br hydrogen bonds) efficiently modulate the organic amine cations penetration and the octahedral distortion. Consequently, this phenomenon induces a phase transition and results in red‐shifted PL emissions, leading to the near‐full‐spectrum emission. This work opens a possibility for achieving wide PL emissions with coverage across the visible light spectrum by employing high pressure in single halide perovskites. [ABSTRACT FROM AUTHOR]

In this paper, the experimentally studied perovskite solar cell structure, ITO/SnO2/(FAPbI3) 1 − x (MAPbBr 3 − y Cly)x/Spiro-OMeTAD/Au, is considered as our primary cell structure. The Solar Cell Capacitance Simulator is used to investigate the cell performance. The cell performance is obtained after optimizing the influence of layer thickness (open circuit voltage = 1. 0 3 V, short circuit current = 2 5. 2 1 mA/cm2, fill factor = 6 5. 4 9 %, power conversion efficiency = 1 7. 0 2 %). In addition, various inorganic hole transporting layers are incorporated in place of Spiro-OMeTAD to improve cell stability and performance. Finally, with an open circuit voltage = 1. 1 3 V, a short circuit current = 2 7. 6 4 mA/cm2, a fill factor = 6 2. 1 5 %, and a power conversion efficiency = 19.55%, the optimized cell structure i.e., ITO/SnO2/(FAPbI3) 1 − x (MAPbBr 3 − y Cly)x/CulnSe2/Au, performs better. The cell performance is examined in relation to defect density in the absorber layer and at the layer interface. The primary cell results are also validated with the existing experimental results in the literature. This research will pave the way for the development of highly efficient mix-cation perovskite solar cells. [ABSTRACT FROM AUTHOR]

Organic lead halide perovskite solar cells (PSCs) have become a viable alternative for next‐generation photovoltaic systems. The significance of reproducibly processing perovskite with less defects comes from the fact that imperfections have a major impact on the solar cell's performance and long‐term stability. Although it is well known that cautious precursor processing has a significant influence on perovskite defect generation, there haven't been extensive investigations on the serial associations between precursor processing, perovskite orientation, and defect generation in PSCs. Making use of a unique precursor chemistry treatment technique that facilitates uniaxially oriented perovskite growth, it is aimed to mitigate defects of sequentially spin‐coated perovskite. Through the temperature‐dependent configurational entropic effect on coordination between iodoplumbate and dimethylsulfoxide (DMSO), a DMSO de‐intercalation processing method is developed. This method enables the induction of uniaxially‐oriented α‐FA0.9MA0.1PbI3‐xBrx (FA: formamidnium, MA: methylammomnium, x < 0.13) perovskite growth parallel to substrates. As a result, this processing delivered significant advances in power conversion efficiency (24.02%) and ambient operational stability under light. This straightforward technique provides a accesible process for producing efficient and stable perovskite solar cells, enabling uniaxially oriented perovskite fabrication without complicated procedures or additional substances. [ABSTRACT FROM AUTHOR]

Ion migration is a major factor affecting the operational stability of perovskite X‐ray detectors, especially under the necessary high working bias. To address this issue, lead‐free tin halide perovskites (FASnI3) being pioneered with the robust Sn─I bond for X‐ray detection. It is observed that the incorporation of propylamine hydroiodide (PAI) to FASnI3‐PAI films can increase activation energy for ion migration (752.18 meV), thereby enhancing the operational stability of X‐ray detectors. The devices based on FASnI3‐PAI demonstrate a significant reduction in dark current drift (1.14 × 10−16 A cm−1 V−1 s−1), with values two orders of magnitude lower than those observed in lead halide perovskites (2.40 × 10−14 A cm−1 V−1 s−1). Moreover, the FASnI3‐PAI films exhibit enhanced film crystallinity, reduced trap density, and improved mobility‐lifetime product, resulting in a high sensitivity of 5535 µC Gyair−1 cm−2 and an ultralow detection limit of 7.95 nGyair s−1. Significantly, high‐contrast X‐ray imaging has also been successfully achieved. [ABSTRACT FROM AUTHOR]

Colloidal lead halide perovskite nanocrystals have potential for lighting applications due to their optical properties. Precise control of the nanocrystal dimensions and composition is a prerequisite for establishing practical applications. However, the rapid nature of their synthesis precludes a detailed understanding of the synthetic pathways, thereby limiting the optimisation. Here, we deduce the formation mechanisms of anisotropic lead halide perovskite nanocrystals, 1D nanorods and 2D nanoplatelets, by combining in situ X-ray scattering and photoluminescence spectroscopy. In both cases, emissive prolate nanoclusters form when the two precursor solutions are mixed. The ensuing antisolvent addition induces the divergent anisotropy: The intermediate nanoclusters are driven into a dense hexagonal mesophase, fusing to form nanorods. Contrastingly, nanoplatelets grow freely dispersed from dissolving nanoclusters, stacking subsequently in lamellar superstructures. Shape and size control of the nanocrystals are determined primarily by the antisolvent's dipole moment and Hansen hydrogen bonding parameter. Exploiting the interplay of antisolvent and organic ligands could enable more complex nanocrystal geometries in the future. Lead halide perovskite nanocrystals show bright and colour-pure emission in the visible range, which can be tuned by nanocrystal size and composition. Here authors present the formation mechanisms of anisotropic lead halide perovskite nanocrystals, 1D nanorods and 2D nanoplatelets, by combining in situ X-ray scattering and photoluminescence spectroscopy. [ABSTRACT FROM AUTHOR]

The industrialization of perovskite (PVK) solar cells (PSCs) necessitates simple manufacturing, cheapness, nontoxicity, high efficiency, and stability. We report an air-processed lead halide PSCs with cheap, nontoxic, stable NiOx and SnO2 as the hole and electron transport layers separately, to meet all the above commercial requests. By preparing the NiOx (water-dispersible) and SnO2 (oil-dispersible) quantum dots (QDs) with good conductivity and energy band matched well with that of PVK, we fabricate inverted PSCs (ITO/NiOx/PVK/SnO2/Ag) with efficiency up to 20.1/14.6% for active areas of 0.0707/1 cm2, under 1 sun simulated illumination with enhanced UV light ratio. The UV-light resistant PSCs reported here will impel their application in the high altitude areas with strong UV light. Importantly, the monodisperse size and dominant (110) plane of SnO2 QDs achieved by controlling the solvothermal parameters, realize the conformal deposition and defect prevention of SnO2, respectively, thus improving the PSC efficiency and stability. [ABSTRACT FROM AUTHOR]

Lead halide perovskite nanocrystals (LHP NCs) are generally prone to surface defect formation during the purification process, resulting in a reduced photoluminescence (PL) quantum yield. The purification of LHP NCs using antisolvents leads to the detachment of surface atoms and ligandsin the form of alkylammonium‐halides or A‐carboxylates (A: Cs, methylammonium, MA, or formamidinium, FA. Currently, intense research is being carried out to improve the surface stability of LHP NCs using various long‐chain organic ligands that strongly bind to the surface of NCs. Herein, the findings on the higher surface stability of hybrid (MAPbBr3 and FAPbBr3) LHP NCs compared to that of inorganic CsPbBr3 NCs against purification with polar antisolvents are reported. It is discovered that the CsPbBr3 NC surface stability can be enhanced (reaching that of hybrid perovskite NCs) by the incorporation of a small amount of MA or FA A‐site organic cations into their lattice, corroborated by the evidence that the PL quantum yield of mixed A‐cation CsxFA1‐xPbBr3 and CsxMA1‐xPbBr3 NCs remains unaffected after several purification cycles. It is hypothesized that this is attributed to hydrogen bonding between the organic A‐site cations and the neighboring halides on the surface. These findings are not only fundamentally important but are also expected to have wide implications in the field of metal‐halide perovskite optoelectronics. [ABSTRACT FROM AUTHOR]

The stereochemical expression of the ns2 lone pair significantly impacts symmetry breaking and corresponding photoelectric properties. However, hindered by the symmetric octahedral configuration, the Pb2+ 6s2 lone pair in the well‐conductive lead halide hybrid perovskites (LHHP) are normally stereo‐inactive, new approaches to activate the 6s2 lone pair are still greatly desired. Herein, by exploiting a perovskitizer tuning Pb2+ lone pair method, the study successfully obtains a stereo‐active 6s2 in the polar perovskite PA2MHy2Pb3Br10 (PMPB, PA = n‐propylamine, MHy = methylhydrazine), and unprecedentedly performs a multiaxial self‐powered X‐ray detection. In detail, the stereo‐active 6s2 lone pair is caused by the coordination bond between the perovskitizer MHy and Pb atom. Emphatically, the N‐Pb bond induces a large angular distortion parameter (≈45 times larger than other LHHP) and the lowest‐symmetric space group (P1) crystallization. Therefore, PMPB natively contains multiaxial polarization, which acts as the driving force to separate and transport the X‐ray‐generated carriers, thus enabling multiaxial self‐powered X‐ray detection with a low detection limit (129 nGy s−1). This work reveals the relationship between stereo‐active lone pair and polarization and sheds light on future X‐ray detection. [ABSTRACT FROM AUTHOR]

Integrating perovskite solar cells with crystalline silicon bottom cells in a monolithic two‐terminal tandem configuration enables power conversion efficiency (PCE) surpassing the theoretical limits of single‐junction cells. However, wide bandgap (WBG) perovskite films face challenges related to phase stability and open circuit voltage (VOC) deficit, particularly due to severe non‐radiative recombination at the perovskite/C60 interface. Here, the interfacial defects are passivated by incorporating a reactive passivator that reacts with lead halides to form low‐dimensional phases. The target product obtained by optimizing the reaction temperature not only suppresses recombination across the interface, but also facilitates the transfer of charge carriers. More importantly, this product can suppress phase segregation of WBG perovskite films under exposure to light illumination and moisture. This strategy enables a high VOC of 1.25 V for WBG perovskite device based on polymer hole transport layer and a certified stabilized PCE of 30.52% for a monolithic perovskite/silicon tandem solar cell. The unencapsulated tandem device retains 94% of its initial PCE over 200 h under continuous 1‐sun full spectrum illumination in air, demonstrating the improved phase stability. [ABSTRACT FROM AUTHOR]

Colloidal cesium lead halide (CsPbX3, X = Cl, Br, I) perovskite nanocrystals (NCs) hold promises in photovoltaic and optoelectronic applications. However, their poor long‐term stability results in degradation of optical properties under ambient conditions. Various methods have been explored to address these issues. In this study, we demonstrate that following 3‐precursor hot‐injection method employing ethylenediammonium dihalide (EDAX2) as an additional ligand/halide source one can obtain phase‐pure, monodispersed, stable, and highly luminescent CsPbX3 NCs. Our violet‐emitting CsPbCl3, blue‐emitting CsPbClBr2, Green‐emitting CsPbBr3, yellow‐emitting CsPbBr2I, and red‐emitting CsPbI3 NCs show PLQYs of 53%, 97%, 96%, 93%, and 95%, respectively. Moreover, the CsPbI3 NCs, which are known for their phase instability, exhibit stability for up to two months under ambient conditions. The enhanced stability and photoluminescence are attributed to strong binding of the bidentate ligand (EDA2+) to the surface of the NCs and effective removal of the halide‐deficiency trap states by X−. [ABSTRACT FROM AUTHOR]

Due to its extreme susceptibility of tin to oxidation, the power conversion efficiency (PCE) of tin–lead mixed perovskite (TLP) solar cells still lags far behind the pure lead halides perovskite solar cells (PSCs). More than the endeavors of the suppression of tin‐oxidation in the bulk TLP films, the synergistic interface engineering of both grain boundaries and interfaces turns more and more important. Here, a synergistic co‐passivation strategy is reported by modulating poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate) (PEDOT:PSS) substrate with p‐guanidinobenzonitrile hydrochloride (CG) and grain boundary passivation of TLP film with 3‐cyano‐4‐hydrazinylbenzoic acid (3C‐HBA), realizing a competitive device PCE of 23.3%, positioning it at the forefront of reported literature. Strikingly, the discovery of CG modifications for such important PEDOT:PSS layer. Moreover, relying on the comprehensive spectroscopies, 3C‐HBA is revealed to effectively modulate the crystallization process of TLP films. This co‐passivation strategy obviously reduces trap density and suppresses Sn2+ oxidation of TLP devices. [ABSTRACT FROM AUTHOR]

Lead halide perovskites (LHPs) are promising for versatile optoelectronic applications due to their tunable bandgap, but their photoinstability impedes the development. Lead iodide (PbI2) inclusions are commonly seen in LHPs, either formed during the fabrication of the thin film or during its degradation under external stimuli like heat and illumination. Here It is shown how the coexistence of these different phases mutually boost their photodegradation. It is demonstrated that the photodecomposition of PbI2 to form I2, and the photo‐induced halide segregation and decomposition of the mixed I─Br perovskite are both accelerated when they are interfaced. Such a mutual destabilization originates from the nature of PbI2, both because it is rich in hole traps whose energy level spreads within the bandgap of perovskite and because it has a loose layered structure. Thus it becomes a sink for both photocarriers (holes) and ions (A‐site cations and halides) transferred from the perovskite, respectively. It is shown that consistently reducing the PbI2 inclusions in the mixed I─Br perovskite thin film improves the solar cell stability substantially, extending, in the model devices, the operational time from ≈10 to 500 h under illumination. [ABSTRACT FROM AUTHOR]

Encapsulating Cs4PbBr6 quantum dots in silicon nano-sheets not only stabilizes the halide perovskite, but also takes advantage of the nano-sheet for a compatible integration with the traditional silicon semiconductor. Here, we report the preparation of un-passivated Cs4PbBr6 ellipsoidal nanocrystals and pseudo-spherical quantum dots in silicon nano-sheets and their enhanced photoluminescence (PL). For a sample with low concentrations of quantum dots in silicon nano-sheets, the emission from Cs4PbBr6 pseudo-spherical quantum dots is quenched and is dominated with Pb2+ ion/silicene emission, which is very stable during the whole measurement period. For a high concentration of Cs4PbBr6 ellipsoidal nanocrystals in silicon nano-sheets, we have observed Förster resonance energy transfer with up to 87% efficiency through the oscillation of two PL peaks when UV excitation switches between on and off, using recorded video and PL lifetime measurements. In an area of a non-uniform sample containing both ellipsoidal nanocrystals and pseudo-spherical quantum dots, where Pb2+ ion/silicene emissions, broadband emissions from quantum dots, and bandgap edge emissions (515 nm) appear, the 515 nm peak intensity increases five times over 30 min of UV excitation, probably due to a photon recycling effect. This irradiated sample has been stable for one year of ambient storage. Cs4PbBr6 quantum dots encapsulated in silicon nano-sheets can lead to applications of halide perovskite light emitting diodes (PeLEDs) and integration with traditional semiconductor materials. [ABSTRACT FROM AUTHOR]

Composite materials which combine the advantages of both embedded constituents have been a successful strategy for developing novel multi‐functional materials. Here, we demonstrate the synthesis of nanoscale materials of organic‐inorganic hybrid lead halide perovskites (OIH‐LHP) with enhanced optoelectronic properties and photostability by utilizing biomimetic ligand, chitosan. Notably, nanocrystals fabricated with chitosan mediated ligands exhibit an increase in photoluminescence quantum yield by 300 % and fluorescence lifetime by 1.5 times. Consequently, the lifetime distribution of the photoluminescence emission decreases to a value as low as 6 ns. More interestingly, even though chitosan is a wide band gap insulating material, its incorporation onto the perovskite NCs enhances the bulk hole mobility by at least an order of magnitude in comparison to the pristine material. With detailed spectroscopic and structural studies, we correlate these enhancements in optoelectronic parameters to the improvement in the crystal quality, phase purity, and minimized poly‐dispersity of the nanocrystals. Development of such composite materials with unprecedented optoelectronic properties and outstanding stability will contribute immensely towards high performance nanocrystal devices. [ABSTRACT FROM AUTHOR]

Lead halide perovskites are notorious for water-sensitivity and low hardness. Consequently, polishing CsPbBr3 crystals to achieve high-quality surfaces is challenging. We present a breakthrough mechanical polishing methodology tailored to the specific needs of these soft, moisture-sensitive semiconductors. Three-dimensional optical surface profiles over ~ 1 mm2 areas demonstrate high-quality surfaces with root-mean-square roughness values (< 10 nm) that are unparalleled for melt-grown CsPbBr3. We additionally delve into the polished wafers' fundamental optical constants and introduce an anti-reflection coating method, setting new standards for short-wave infrared transparency in CsPbBr3. These pivotal processing guidelines pave the way for advancing halide perovskite applications beyond academic curiosity. [ABSTRACT FROM AUTHOR]

Zero‐dimensional (0D) hybrid manganese halides have gained wide attention for the various crystal structures, excellent optical performance and scintillation properties compared with 3D lead halide perovskite nanocrystals. In this work, a new family of 0D hybrid manganese halides of A2MnBr4 (A = BzTPP, Br‐BzTPP, and F‐BzTPP) based on discrete [MnBr4]2− tetrahedral units is reported as highly efficient lead‐free scintillators. Excited by UV or blue light, these hybrids emit bright green light originating from the d–d transition of Mn2+ with near‐unity PLQY (99.5%). Significantly, high PLQY and low self‐absorption render extraordinary radioluminescence properties with the highest light yield of 80,100 photons MeV−1, which reached the climax of present hybrid manganese halides and surpassed most commercial scintillators. The radioluminescence intensity features a linear response to X‐ray doses with a detection limit of 30 nGyair s−1, far lower than the requirement of medical diagnostic (5.5 µGyair s−1). X‐ray imaging demonstrates ultrahigh spatial resolution of 14.06 lp mm−1 and short afterglow of 0.3 ms showcasing promising application prospects in radiography. Overall, we demonstrated new hybrid manganese halides as promising scintillators for advanced applications in X‐ray imaging with multiple superiorities of nontoxicity, facile‐assembly process, high irradiation light yield, excellent resolution, and stability. [ABSTRACT FROM AUTHOR]

Cs2AgInCl6 belongs to the family of lead-free halide double perovskites. Lead-free halide double perovskite appears as a viable contender for scintillator applications due to its inexpensive production costs, low intrinsic trap density, and nanosecond quick reaction. Perovskite crystals have a substantially lower trap density than lead halide and traditional oxide scintillator materials, according to thermo-luminescence measurements. Cs2AgInCl6 structure and dimensionality were engineered by Bi doping. Bi substitution reduces the bandgap, making it suited for scintillation applications. Bi substitution allows for easy tuning of Cs2AgIn(1−x)BixCl6 (0 ≤ x ≤ 50) due to its wide versatility in scintillation properties. For Cs2AgIn(1−x)BixCl6 (0 ≤ x ≤ 50), x-ray power dependent luminescence increases with increasing power. Because of their nontoxicity, sensitivity, reaction time, and stability, Cs2AgIn(1−x)BixCl6 (0 ≤ x ≤ 50) double perovskite crystals are promising for x-ray scintillation. [ABSTRACT FROM AUTHOR]

All‐inorganic cesium lead halide flexible perovskite solar cells (f‐PSCs) exhibit superior thermal stability compared to their organic‐inorganic hybrid counterparts. However, their flexibility and efficiency are still below‐par for practical viability. This study presents an approach involving the introduction of multifunctional molecule ammonium benzenesulfonate (ABS) to selectively etch 0D‐Cs4Pb(IBr)6 from the mixed‐dimensional perovskite film surface, to attain more contact area between the perovskite and hole transport layer for improved hole extraction and transport. It is found that the ABS molecules bind to the perovskite lattice surface via O atoms and NH4+, effectively passivating surface defects and enhancing phase stability. The hydrophobic nature of the benzene ring in ABS further contributes to operational stability, leading to high cell efficiency of 15.00%, accompanied by enhanced operational stability. Even after undergoing 60 000 flexing cycles at a curvature radius of 5 mm, the ABS‐treated f‐PSC still retains over 98.5% of its initial efficiency. This multifunctional strategy for modifying typical mixed‐dimensional perovskite compositions significantly enhances the photovoltaic performance and stability of flexible all‐inorganic f‐PSCs. [ABSTRACT FROM AUTHOR]

Dynamic memristors are considered as the optimal hardware devices for reservoir computing (RC) enabled by their nonlinear conductance variations. This significantly reduces the extensive training workload typically required by traditional neural networks. Lead halide perovskites, with their tunable band structure and active ion migration properties, have emerged as highly promising materials for developing dynamic memristors. However, large‐scale and consistently stable production remains a challenge for perovskite functional films, while lead elements' toxicity and environmental impact also partly restrict their practical device utilization. In this work, lead‐free copper‐based perovskite (i.e., CsCu2I3) films are prepared by thermal evaporation for constructing dynamic memristors. The effective conductivity modulation of CsCu2I3‐based memristor can be utilized in artificial neural networks, achieving a high handwritten digit recognition accuracy of 91.2%. In addition, the RC system is also constructed based on the dynamic behavior of the devices, by which a letter recognition accuracy of 98.2% with simple training is achieved. This technology provides a feasible pathway to construct copper‐based perovskite dynamic memristors for future neural network information processing. [ABSTRACT FROM AUTHOR]

Chiral lead halide perovskites have captivated considerable attentions due to their distinctive attributes, such as ferroelectricity, spin‐dependent transport, and chiroptical activity. However, lead toxicity and weak circularly polarized luminescence (CPL) have cast a pall over their practical applications. Here, a series of 0D lead‐free chiral enantiomorphic hybrids, such as (R‐/S‐MBA)3In1‐xSbxCl6 (x = 0–1) is successfully developed. By optimizing the Sb3+ doping concentration to 0.55%, the resultant (R‐/S‐MBA)3In99.45%Sb0.55%Cl6 not only shows a near‐unity quantum yield but also emanates potent CPL, boasting a dissymmetry factor (glum) of 6.3 × 10–3. These efficient CPL activities are intricately tied to the presence of a twisted luminescent cluster [SbCl6]3– induced by structural chirality. The comprehensive results reveal that the emission of the chiral perovskite originated from self‐trapped excitons (STEs) of 5s2 Sb3+ ions. Moreover, (MBA)3In99.45%Sb0.55%Cl6 single crystals also exhibit bright orange emission and UV detector signals. These findings will pave the way for the further investigation in efficient CPL and detectors based on lead‐free chiral optoelectronic materials. [ABSTRACT FROM AUTHOR]

Metal halide materials have recently drawn increasing research interest for their excellent opto‐electronic properties and structural diversity, but their resulting rigid structures render them brittle and poor formability during manufacturing. Here we demonstrate a thermoplastic luminant hybrid lead halide solid by integrating lead bromide complex into tri‐n‐octylphosphine oxide (TOPO) matrix. The construction of the hybrid materials can be achieved by a simple dissolution process, in which TOPO molecules act as the solvents and ligands to yield the monodispersed clusters. The combination of these functional units enables the near‐room‐temperature melt‐processing of the materials into targeted geometry by simple molding or printing techniques, which offer possibilities for fluorescent writing inks with outstanding self‐healing capacity to physical damage. The intermarriage between metal halide clusters with functional molecules expands the range of practical applications for hybrid metal halide materials. [ABSTRACT FROM AUTHOR]

Lead halide perovskite nanocrystals (LHP‐NCs) incorporated within polymer matrices have emerged as promising materials for various photonic applications. However, challenges persist in achieving high‐quality nanocomposites due to low monomer conversion yields, restricted LHP‐NCs loadings, and difficulty in maintaining NCs integrity post‐polymerization. A novel protocol for synthesizing LHP‐NCs/poly(methyl methacrylate) nanocomposites in a single step via the NC‐initiated photoinduced electron transfer‐reversible addition‐fragmentation chain transfer (PET‐RAFT) method is presented. Polymerization initiation mediated by NCs surfaces under blue light enables the fabrication of homogeneous nanocomposites with NCs loadings up to 7% w/w and ≈90% monomer conversion even in the presence of oxygen. This process preserves the optical quality of the NCs and passivates NCs surface defects, resulting in nanocomposites exhibiting near unity luminescence efficiencies. The potential of this approach for producing highly loaded nanocomposites for radiation detection is validated by radioluminescence measurements showing light yield values of 6000 ph MeV−1 and fast scintillation dynamics with effective lifetime of 490 ps, showing promise for time‐of‐flight radiometry. [ABSTRACT FROM AUTHOR]

In the presented work, the structure dependence as well as luminescence features of a wide range of hybrid crystals based on lead halides and a homologous series of alkyl diamines from 1,4-diaminobutane to 1,8-diaminooctane are investigated. The structure of several previously undescribed hybrid crystals has been established. The even–odd effect of alkanes and its influence on the structure of such hybrid crystals have been demonstrated for the first time. The luminescence properties of the crystals and their dependence on the type of anion as well as the length and oddity of the organic cation are described in detail. The obtained data expand our knowledge of the relationship between the structure of the organic cation, including its parity and structure, and the electronic and optical properties of the hybrid crystals. [ABSTRACT FROM AUTHOR]

Halide perovskites have received an immense attention in the field of optoelectronics due to their outstanding photophysical properties. But so far, lead‐based halide perovskites still account for most of the research, which raises concerns due to lead toxicity. Herein, a new design strategy is proposed utilizing a super large, energetically higher singlet and triplet energy levels aromatic organic cation to incorporate into the perovskite structure, forming ultra‐stable high‐performance 2D/3D (quasi‐2D) perovskite. The judicious molecular design of connecting all the phenyl groups at their meta sites ensures the simultaneous achievement of a large molecular weight and high singlet and triplet energy levels. The resulting quasi‐2D perovskite thin films not only exhibits excellent emission properties but also, surprisingly, show long‐term waterproof‐level stability. The robustness of these perovskites is confirmed by their extraordinary emission stability upon direct water immersion and almost undetectable lead release in water. Proof‐of‐concept of a water‐resistant color conversion‐type perovskite near‐infrared (NIR) light‐emitting diode (LED) is demonstrated, showing high external quantum efficiency (EQE) and power conversion efficiency (PCE) of 20.5% and 13.3%, respectively. It is believed these results and strategy pave a new way for realizing environmentally friendly lead halide materials and devices. [ABSTRACT FROM AUTHOR]

2D organic–inorganic hybrid lead halide perovskite films are fascinating optoelectronic materials for white‐light emission and lasing applications. Here, it is demonstrated that nano‐meter‐thick films of perovskites can be formed at room temperature using Langmuir–Schaefer (LS) deposition technique. In situ X‐ray measurements reveal a self‐assembly process of the 2D perovskite formation at the air–water interface. This formation process requires the presence of stearic acid monolayer on the water subphase having a solution of lead‐perovskite in dimethylformamide. Microscopy and X‐ray measurements of these nanofilms transferred onto substrates show crystalline phase formation that deviates from the known orthorhombic structure of the bulk crystals. The nanofilms exhibit novel broad optical emission with sharp band‐edge transition in temperature‐dependent photoluminescence studies. Also, their band‐edge emission is distinctly blue‐shifted compared to that of thicker 2D perovskite flakes prepared by the slow‐cooling chemical synthesis process. 2D flakes exhibit lasing that cannot be obtained in the LS nanofilms as their thicknesses are lower than the lasing wavelength prohibiting wave‐guide formation. The results show that the 2D single‐crystalline nature of the LS films and flakes are suitable materials to develop broad‐band white light emission across the entire visible range and to obtain lasing without external cavities, respectively. [ABSTRACT FROM AUTHOR]

Field observations have confirmed that halide ions are widely distributed among aerosols from the marine boundary layer and on the surfaces of ice and snow in polar regions. Consequently, the coexistence of halide ions may play a more significant role in nitrate photolysis than previously thought. In this study, we simultaneously measured HONO, NO2, and NO2- in situ to gain a deeper understanding of the coexisting system, including the photogenerated nitrogen products and the effects on nitrate photolysis rates due to enhanced aqueous nitrite and HONO transfer rates by halides. The presence of halides significantly increased the photogenerated nitrogen products across various molar ratios ([X-]/[NO3-]) at pH 3.5. By eliminating oxygen flux, the transformation of the primary photogenerated products was affected, resulting in higher concentrations of N(III) as both HONO and NO2-. Experiments involving OH scavengers indicated that the attack from-OH initiated by halides leads to side reactions that enhance nitrate photolysis. Both theoretical calculations and nitrate actinometry were used to determine the photolysis rate of nitrate solutions, which together indicated that the presence of halides enhances nitrate photolysis. A newly developed model was used to determine the HONO transfer rate, finding that the presence of halides ([X-]/[NO3-] = 0.2) enhanced the evaporation of N(III) in solution by factors of 0.68, 0.95, and 1.27 for Cl-, Br-, and I-, respectively. To our knowledge, this is the first determination of halide effects on the mass transfer of HONO. The enhanced nitrate photolysis rate can be attributed to the differential surface effects of halides and parallel reactions initiated via -OH stemming from nitrate photolysis, with varying rates leading to different quantities of nitrogenous products. Additionally, simultaneous measurements of photoproducts in both gas and condensed phases are recommended to better constrain the rate constants of NO3- photolysis. [ABSTRACT FROM AUTHOR]

Fluorescent lead halide perovskite quantum dots (LH PQDs) micropatterns hold great potential for photonic applications. However, current photolithography for LH PQDs micropatterning is hindered by their incompatibility with traditional photolithography methods, which involve development processes using numerous solvents and exhibit poor stability due to the ionic characteristics of LH PQDs. Herein, a direct in situ photolithography to fabricate CsPbBr3 PQDs micropatterns based on ultraviolet‐C light‐driven debromination is developed. Using this approach, fluorescent CsPbBr3 PQDs micropatterns with high theoretical information storage capacity (up to 10750205) can be achieved in a single step, without the need for tedious development processes. Furthermore, the fabricated CsPbBr3 PQDs micropatterns show high stability, remaining undamaged even after immersion in water for 6 months. The combination of excellent optical properties, development‐free process, high stability, and low cost makes the in situ photolithography strategy very promising for patterning LH PQDs toward photonic integrations. [ABSTRACT FROM AUTHOR]