http://onlinelibrary.wiley.com/rss/journal/10.1002/(ISSN)1521-4095

This study presents a novel strategy for the photochemical closed-loop recycling of hydroxyl-rich polymers. Simple bis-aldehyde precursors are employed to synthesize polypinacols via UV light irradiation. Subsequent depolymerization is achieved under visible light using a cerium-based photocatalyst, enabling monomer recovery through selective cleavage of C─C bonds within the polymer backbone.

The development of innovative recycling strategies for polymers is crucial to addressing the rapidly growing plastic waste challenge. While thermal ground-state chemistry is the standard for closed-loop chemical recycling, the potential of photochemical excited-state chemistry remains largely unexplored. This study bridges this gap by investigating light-driven polymerization and depolymerization processes for hydroxyl-rich polymers. Through consecutive pinacol coupling reactions, a range of simple bis-aldehyde monomers is photopolymerized into well-defined polypinacols on a gram scale. These polymers exhibit excellent thermal stability, retaining their integrity up to 306 °C, with glass transition temperatures ranging from 72 to 137 °C. Using an earth-abundant cerium photocatalyst, selective cleavage of stable C─C bonds within the polypinacol backbone is achieved under visible light, efficiently regenerating the original monomer. As this approach tolerates the presence of standard commodity plastics, it presents an opportunity for orthogonal recycling methods that could help recover specific polymers from diverse plastic waste streams. The successful completion of one recycling cycle, resulting in a polymer with comparable properties to the original, highlights the significant potential and advantages of (photo)chemical recycling.

The welding of CNTs for the first time by a fast chemical-vapor-deposition self-assembly (FCVDS) technique using TiO2 nanoparticles as the solder is reported. It is simple, fast, pressure-free, and applicable to ambient conditions. The welded junctions have the highest strength realized in nanowelding field so far, to the best of the knowledge.

The strength of carbon nanotube (CNT) bundles and fibers is generally much lower than that of single CNTs, the short length of CNT components results in the assembly strength can only be contributed by the weak shearing interaction between CNTs. Here, the welding of CNTs by a fast chemical-vapor-deposition self-assembly (FCVDS) technique using TiO2 nanoparticles as the solder is reported. It is simple, fast, pressure-free, applicable to ambient conditions, and can weld samples with macroscale length. The welded junctions have a mechanical strength approaching the tensile strength of a single CNT. Whereas the interface interaction between TiO2 and CNTs is only contributed by Van der Waals forces, avoiding the destruction of the defect-free structure of CNTs. The solder mass can be only ≈1 wt% of welded CNTs.

A deployable ultrathin femtosecond vortex laser based on a BIC-enabled polymer membrane is demonstrated, delivering MW/cm2 peak power and structured light emission. With its modular design and compact footprint, it is considered promising for integration into advanced imaging and lithography.

Ultrafast vortex lasers, capable of emitting structured femtosecond pulses with orbital angular momentum, hold great potential for high-speed optical communications, super-resolution imaging, and advanced laser processing. However, the direct generation of femtosecond vortex pulses in micro/nanoscale lasers remains a major challenge. Here, an ultrathin deployable femtosecond vortex laser based on a ≈200 nm-thick conjugated polymer gain membrane integrated with a square-lattice photonic crystal supporting symmetry-protected bound states in the continuum mode is demonstrated. The high-Q vortex modes driven by Purcell enhancement enable low-threshold (1.5 µJ cm2), femtosecond (≈600 fs) vortex pulse emission with peak power reaching several MW/cm2. The freestanding membrane can be modularly deployed onto arbitrary substrates, where direct laser fabrication is challenging. When deployed onto an optical mirror, the membrane laser achieved unidirectional emission, nearly doubling its output efficiency. Furthermore, a confocal optical path aligned the vortex laser coaxially with the pump light, highlighting its potential as an integrated module for simplifying super-resolution imaging and lithography techniques.

A bilateral anchoring strategy using 2-bromoethylamine hydrobromide (2-BH) at PEDOT:PSS/perovskite interface enhances interfacial adhesion and charger transfer in flexible Sn-Pb perovskite solar cells. The introduction of 2-BH additionally mitigates Sn2+ oxidation, thereby improving the film morphology and crystallinity. Overall, such optimized flexible all-perovskite tandem solar cells achieve a power conversion efficiency of 24.1% and present superior mechanical durability.

Flexible all-perovskite tandem solar cells (TSCs) feature an outstanding power-to-weight ratio, rendering them perfect for building-integrated photovoltaic, wearable electronics, and aerospace applications, owing to their adaptability to flexible and lightweight substrates. However, the weak mechanical adhesion between the perovskite and adjacent functional layers, combined with tin (Sn) oxidation at the buried interface in tin-lead (Sn-Pb) narrow-bandgap (NBG) perovskites solar cells (PSCs), substantially hampers the durability and performance of device. Herein, a bilateral anchoring strategy is proposed by employing 2-bromoethylamine hydrobromide (2-BH) at the NBG perovskite/ hole transporting layer (PEDOT:PSS) interface. The incorporation of 2-BH establishes robust bonds with both PEDOT:PSS and the perovskite layer, thereby enhancing interfacial adhesion and charge transfer. Meanwhile, the morphology and crystallinity of the perovskite films are also improved due to the mitigated oxidation of Sn2+. Thus, this approach yields flexible single-junction NBG  with a power conversion efficiency (PCE) of 18.5%, maintaining its 95% efficiency after 3000 bending cycles. When integrated into monolithic flexible all-perovskite TSCs, a certified PCE of 24.01% is achieved.

Given the critical role of electrolyte engineering in advancing secondary batteries with high energy density and enhanced safety, this review aims to provide a comprehensive analysis of nitrile-based electrolytes. It explores the electrochemical behavior of nitriles as solvents and additives, and their influence on battery performance, and highlights recent advancements and challenges for future development.

Nitriles have gained attention as promising candidates for secondary battery electrolytes due to the high polarity of cyano groups, excellent cathode compatibility, remarkable oxidation resistance, and broad thermal stability. As additives, nitriles effectively stabilize cathode surfaces and inhibit the dissolution of transition metals. Besides, as the electrolyte solvent, the characteristics of a wide liquidus range, excellent high-voltage tolerance, and superior conductivity endow it with outstanding performance. Moreover, nitriles are also beneficially applied in solid-state electrolytes, offering advantages such as strong cation coordination, excellent thermal and electrochemical stability, and enhanced ionic conductivity. However, obstacles such as side reactions with anodes, the formation of non-robust SEI layers, and inherent toxicity hinder their broader application. Herein, the mechanism of nitriles as additives, and the application progress of nitriles in liquid electrolytes and solid-state electrolytes are introduced in detail. Furthermore, the current challenges faced by nitriles are in depth analyzed, and the advanced modification strategies of nitriles as secondary battery electrolytes are thoroughly summarized and discussed. Additionally, the future development of nitriles in the field of secondary batteries is prospected. This review provides important references for the future development of nitrile-based electrolytes, with guiding significance for other electrolyte solvents and additives.

This article explores the development of materials with multi-scale control at the nanoscale (<100 nm), micrometer-scale (80 µm), and macro-scale (multi-component geometries). This is achieved by applying polymerization-induced microphase separation (PIMS) process via volumetric 3D printing (Xolography), expanding the design space for functional nanomaterials in diverse applications.

Light-mediated 3D printing has revolutionized additive manufacturing, progressing from pointwise stereolithography, to layer-by-layer digital light processing, and most recently to volumetric 3D printing. Xolography, a novel light-sheet-based volumetric 3D printing approach, offers high-speed and high-precision fabrication of complex geometries unattainable with traditional methods. However, achieving nanoscale control (<100 nm) within these 3D printing systems remains unexplored. This work leverages polymerization-induced microphase separation (PIMS) within the xolography process to prepare network polymer materials with simultaneous control over feature sizes at the nano-, micro-, and macro-scale. By controlling the chain length and mass fraction of macromolecular chain transfer agents used in the PIMS process, precise manipulation of nanodomain size within 3D printed materials is demonstrated, while optimization of the other resin components enables the fabrication of rigid materials with feature sizes of 80 µm. Critically, the rapid one-step fabrication of complex and multi-component structures such as a functional waterwheel with interlocking parts, at high volume-building rates is showcased. This combined approach expands the design space for functional nanomaterials, opening new avenues for applications in diverse fields such as polymer electrolyte membranes, biomedical delivery systems, and semi-permeable microcapsules.

This study proposes tribenzyl organic cation carried multidentate X-type Lewis soft base to enhance adhesion and passivate defects simultaneously, aiming to achieve foldable and efficient perovskite nanocrystal-based light-emitting diodes. The resulting pure red F-PeLEDs exhibit a recorded high EQE of 16.2% and robust mechanical properties to endure 5000 folding cycles with small radius of 1 mm.

Lead-halide perovskite nanocrystals (PNCs) exhibit significant potential for advancing foldable perovskite light-emitting diodes (F-PLEDs) due to their discrete crystalline morphology, bright emission across an extensive color gamut, and remarkable color purity; however, their progression remains in the early stages with the concerns of inadequate performance and mechanical instability. This study proposes a ligand strategy employing tribenzyl organic cation (tribenzylamine, TBA) carried multidentate X-type Lewis soft base (sodium acid pyrophosphate, SAPP) to address the challenges above simultaneously. Specifically, the use of multibranched aromatic ligands considerably improved the adhesion force between PNCs and adjacent layers, enhancing mechanical stability during folding, while the control sample shows deleterious cracks. Additionally, TBA-SAPP ligands effectively eliminate the defects in PNC film, yielding exceptional photoluminescence properties with a near-unity quantum yield. Consequently, the multifunctional ligands improved F-PLEDs to achieve a record-high external quantum efficiency (EQE) of 16.2% compared to the previously reported pure-red flexible PLEDs and display substantially improved spectral and operational stability. Equally important, these devices demonstrate robust mechanical properties, enduring a small folding radius of 1 mm for 5000 cycles. This ligand strategy is anticipated to inspire relevant research in PNCs and promote the realization of highly efficient and mechanically stable F-PLEDs.

Synergistic Hybrid-Ligand Passivation of Perovskite Quantum Dots

This illustration demonstrates multi-functional CsPbI3 perovskite quantum dot (PQD) solids with high luminescence, conductivity, and stability fabricated by synergistic hybrid-ligand exchange and passivation strategies. The multiple interactions between introduced ligands not only improve inherent properties but also suppress the dimensionality change that cause severe stability degradation of PQDs. Therefore, hybrid-ligand strategies enable realizing highly efficient and stable optoelectronic device. More details can be found in article number 2410128 by Jongmin Choi, Bo Ram Lee, Younghoon Kim, and co-workers.

Light-Emitting Diodes

The cover is an artist's representation of the halide perovskite structure (top part of the image) and of the implementation of halide perovskite and perovskite related nanocrystals in light emitting diodes (bottom part). These applications are facilitated by the high luminescence efficiency, wide color gamut, high color purity, and facile synthesis of this class of nanomaterials. More details can be found in article number 2415606 by Jinfei Dai, Zhifeng Shi, Liberato Manna, and co-workers.

Compared to unstable-spectra mixed-halide perovskites, pure bromide blue perovskites have demonstrated good spectral stability. Here, the recent advances of blue light-emitting diodes (LEDs) on pure bromide perovskites are summarized and categorized according to the different strategies of tuning emission. Moreover, the challenges and research directions for achieving highly bright, efficient, and stable blue perovskite LEDs in the future are also addressed.

Blue perovskite light-emitting diodes (LEDs) are essential for the creation of full-color displays and white-light illumination, and some significant progress is made in recent years. However, most high-performance blue perovskite LEDs are currently based on mixed-halide perovskites and suffer from unstable spectra due to inevitable halide phase segregation, which is unfavorable for the application of blue perovskite LEDs. In contrast, blue emissions from pure bromide perovskites generally exhibit stable spectra (consistent emission peak positions and spectral shapes) and are worthy of attention. In this review, the recent advances in blue LEDs based on pure bromide perovskites according to different strategies are classified and summarized. Moreover, the challenges related to poor charge injection, high defect-state density, lack of high-performance in the deeper blue region, and inferior operational stability are addressed. Finally, an outlook is provided on feasible future research directions for highly bright, efficient, and stable blue perovskite LEDs.

This review covers the key fabrication techniques for large-area perovskite LEDs (PeLEDs), including spin coating, blade coating, inkjet printing, and vacuum thermal evaporation. The pros and cons of each method are discussed in detail, along with the latest advances in large-area PeLEDs development. Specific challenges are discussed and potential improvement strategies are proposed, all of which are crucial for scalable PeLEDs production. The goal of this review is to offer guidelines for overcoming the challenges in fabricating large-area devices.

Metal halide perovskite light-emitting diodes (PeLEDs) have shown promise for high-definition displays and flat-panel lighting because of their wide color gamut, narrow emission band, and high brightness. The external quantum efficiency of PeLEDs increased rapidly from ≈1% to more than 25% in the past few years. However, most of these high-performance devices are fabricated using a spin coating method with a small device area of <0.1 cm2, limiting their commercial applications. Recently, large-area PeLEDs have attracted growing attention and significant breakthroughs have been reported. This perspective first introduces the pros and cons of each technique in making large-area PeLEDs. The advances in the fabrication of large-area PeLEDs are then summarized using spin coating and mass-production methods such as inkjet printing, blade coating, and thermal evaporation. Moreover, the challenging issues will be discussed that are urgent to be solved for large-area PeLEDs.

This review discusses the roles of charge transport layers (CTLs) in perovskite light-emitting diodes (Pero-LEDs) and categorizes both reported and potential CTL materials. Then, various CTL optimization strategies are presented, alongside an analysis of the selection criteria for CTLs in high-performance Pero-LEDs. Finally, a summary and outlook on the potential of CTL modulation to further advance Pero-LED performances are provided.

Perovskite light-emitting diodes (Pero-LEDs) have garnered significant attention due to their exceptional emission characteristics, including narrow full width at half maximum, high color purity, and tunable emission colors. Recent efficiency and operational stability advancements have positioned Pero-LEDs as a promising next-generation display technology. Extensive research and review articles on the compositional engineering and defect passivation of perovskite layers have substantially contributed to the development of multi-color and high-efficiency Pero-LEDs. However, the crucial aspect of charge transport layer (CTL) modulation in Pero-LEDs remains relatively underexplored. CTL modulation not only impacts the charge carrier transport efficiency and injection balance but also plays a critical role in passivating the perovskite surface, blocking ion migration, enhancing perovskite crystallinity, and improving light extraction efficiency. Therefore, optimizing CTLs is pivotal for further enhancing Pero-LED performance. Herein, this review discusses the roles of CTLs in Pero-LEDs and categorizes both reported and potential CTL materials. Then, various CTL optimization strategies are presented, alongside an analysis of the selection criteria for CTLs in high-performance Pero-LEDs. Finally, a summary and outlook on the potential of CTL modulation to further advance Pero-LED performances are provided.

This manuscript elucidates the relationship between the structure and optoelectronic properties of reduced-dimensional perovskites (RDPs) and describes their carrier recombination behaviours. It highlights the importance of the QW thickness distribution in RDPs for achieving high-efficiency light-emitting diodes and summarizes the latest advances in controlling the QW thickness distribution of RDPs.

Reduced-dimensional perovskites (RDPs), a large category of metal halide perovskites, have attracted considerable attention and shown high potential in the fields of solid-state displays and lighting. RDPs feature a quantum-well-based structure and energy funneling effects. The multiple quantum well (QW) structure endows RDPs with superior energy transfer and high luminescence efficiency. The effect of QW confinement directly depends on the number of inorganic octahedral layers (QW thickness, i.e., n value), so the distribution of n values determines the optoelectronic properties of RDPs. Here, it is focused on the QW thickness distribution of RDPs, detailing its effect on the structural characteristics, carrier recombination dynamics, optoelectronic properties, and applications in light-emitting diodes. The reported distribution control strategies is also summarized and discuss the current challenges and future trends of RDPs. This review aims to provide deep insight into RDPs, with the hope of advancing their further development and applications.

This review focuses on the developments of lead-free perovskite light-emitting diodes, with a particular emphasis on tin-based devices. Recent progress in device efficiency enhancements through the refinement of material properties and the optimization of device configurations are discussed. The key challenges in device instability are analyzed, with strategies that may lead to stable operation and important future directions proposed.

Metal halide perovskites have been identified as a promising class of materials for light-emitting applications. The development of lead-based perovskite light-emitting diodes (PeLEDs) has led to substantial improvements, with external quantum efficiencies (EQEs) now surpassing 30% and operational lifetimes comparable to those of organic LEDs (OLEDs). However, the concern over the potential toxicity of lead has motivated a search for alternative materials that are both eco-friendly and possess excellent optoelectronic properties, with lead-free perovskites emerging as a strong contender. In this review, the properties of various lead-free perovskite emitters are analyzed, with a particular emphasis on the more well-reported tin-based variants. Recent progress in enhancing device efficiencies through refined crystallization processes and the optimization of device configurations is also discussed. Additionally, the remaining challenges are examined, and propose strategies that may lead to stable device operation. Looking forward, the potential future developments for lead-free PeLEDs are considered, including the extension of spectral range, the adoption of more eco-friendly deposition techniques, and the exploration of alternative materials.

Organic–inorganic hybrid metal halide perovskites are multifunctional semiconductors carrying both orbital and spin momentum toward forming strong spin-orbital coupling (SOC). Consequently, the orbital and spin momentum provide dual tuning mechanisms to advance the photoluminescence (PL), circularly-polarized luminescence (CPL), amplified spontaneous emission (ASE), photovoltaic responses (JSC), ferroelectricity (P), and optically-induced magnetization (M).

Organic–inorganic hybrid metal halide perovskites carrying strong spin-orbital coupling (SOC) have demonstrated remarkable light-emitting properties in spontaneous emission, amplified spontaneous emission (ASE), and circularly-polarized luminescence (CPL). Experimental studies have shown that SOC plays an important role in controlling the light-emitting properties in such hybrid perovskites. Here, the SOC consists of both orbital (L) and spin (S) momentum, leading to the formation of J (= L + S ) excitons intrinsically involving orbital and spin momentum. In general, there are three issues in determining the effects of SOC on the light-emitting properties of J excitons. First, when the J excitons function as individual quasi-particles, the configurations of orbital and spin momentum directly decide the formation of bright and dark J excitons. Second, when the J excitons are mutually interacting as collective quasi-particles, the exciton–exciton interactions can occur through orbital and spin momentum. The exciton–exciton interactions through orbital and spin momentum give rise to different light-emitting properties, presenting SOC ordering effects. Third, the J excitons can develop ASE through coherent exciton–exciton interaction and CPL through exciton-helical ordering effect. This review article discusses the SOC effects in spontaneous emission, ASE, and CPL in organic–inorganic hybrid metal halide perovskites.

This review discusses the exciton dynamics in layered halide perovskitelight-emitting diodes (PeLEDs). It opens with a summary of the structural and photophysical aspects, followed by an exploration of controlling dimensionality and cascade exciton transfer in quasi-2D PeLEDs. The review also addresses complex dynamics, such as multiexciton processes and triplet exciton dynamics, which are often overlooked.

Layered halide perovskites have garnered significant interest due to their exceptional optoelectronic properties and great promises in light-emitting applications. Achieving high-performance perovskite light-emitting diodes (PeLEDs) requires a deep understanding of exciton dynamics in these materials. This review begins with a fundamental overview of the structural and photophysical properties of layered halide perovskites, then delves into the importance of dimensionality control and cascade energy transfer in quasi-2D PeLEDs. In the second half of the review, more complex exciton dynamics, such as multiexciton processes and triplet exciton dynamics, from the perspective of LEDs are explored. Through this comprehensive review, an in-depth understanding of the critical aspects of exciton dynamics in layered halide perovskites and their impacts on future research and technological advancements for layered halide PeLEDs is provided.

In situ fabricated perovskite quantum dots (PQDs) simplify the integration into functional systems with enhanced performance. This paper reviews the methodologies and the developments of in situ fabricated PQDs. Furthermore, the fundamental problems in development of PQDs toward industrialization are discussed, such as the photoinduced decomposition under high-intensity light irradiation, ion migration under electrical bias, and the thermal quenching.

Due to the low formation enthalpy and high defect tolerance, in situ fabricated perovskite quantum dots offer advantages such as easy fabrication and superior optical properties. This paper reviews the methodologies, functional materials of in situ fabricated perovskite quantum dots, including polymer nanocomposites, quantum dots doped glasses, mesoporous nanocomposites, quantum dots-embedded single crystals, and electroluminescent films. This study further highlights the industrial breakthroughs of in situ fabricated perovskite quantum dots, especially the scale-up fabrication and stability enhancement. Finally, the fundamental challenges in developing perovskite quantum dots for industrial applications are discussed, with a focus on photoinduced degradation under high-intensity light irradiation, ion migration under electrical bias and thermal quenching at high temperature.

This review explores the advances in halide perovskite lasers, covering key topics such as emission properties, optical gain mechanisms, and diverse laser architectures. It also discusses challenges related to CW-pumped and electrically driven lasing and outlines future research directions aimed at improving material durability, optimizing thermal management, and developing fabrication techniques for scalable, efficient devices.

Over the past decade, semiconducting halide perovskite lasers have emerged as a transformative platform in optoelectronics, owing to unique properties such as high photoluminescence quantum yields, tunable bandgaps, and low-cost fabrication processes. This review systematically examines the advancements in halide perovskite lasers, covering diverse laser architectures, such as whispering gallery mode, Fabry–Pérot, plasmonic, bound states in the continuum (BIC), quantum dot, and polariton lasers. The mechanisms of optical gain, the role of material engineering in optimizing lasing performance, and the challenges associated with continuous-wave (CW) pumping and electrically driven lasing are discussed. Furthermore, recent progress in improving the stability and scalability of perovskite lasers, essential for their integration into practical applications in displays, optical communications, sensing, and integrated photonics is highlighted. Finally, future research directions are discussed, emphasizing the potential of perovskite lasers to revolutionize various technological domains by enabling the development of next-generation photonic devices.