Two-dimensional Hybrid Perovskites: from Static and Dynamic Structures to Potential Applications.

Two-dimensional (2D) perovskites have received great attention recently due to their structural tunability and environmental stability, making them highly promising candidates for various applications by breaking property bottlenecks that affect established materials. However, in 2D perovskites, the complicated interplay between organic spacers and inorganic slabs makes structural analysis challenging to interpret. A deeper understanding of the structure-property relationship in these systems is urgently needed to enable high-performance tunable optoelectronic devices. Herein, we examine how structural changes, from constant lattice distortion and variable structural evolution, modeled with both static and dynamic structural descriptors, affect macroscopic properties and ultimately device performance. We report the effect of chemical composition, crystallographic inhomogeneity, and mechanical-stress-induced static structural changes and corresponding electronic band variations. Additionally, the structure dynamics are described from the viewpoint of anharmonic vibrations, which impact electron-phonon coupling and the carriers' dynamic processes. Correlated carrier-matter interactions, known as polarons and acting on fine electronic structures, are then discussed. Finally, we propose reliable guidelines to facilitate design to exploit structural features and rationally achieve breakthroughs in 2D perovskite applications. This review provides a global structural landscape of 2D perovskites, expected to promote the prosperity of these materials in emerging device applications. This article is protected by copyright. All rights reserved.

Efficient red thermally activated delayed fluorescence emitters achieved through precise control of excited state energy levels.

The variety of highly efficient red/near-infrared (NIR) materials with thermally activated delayed fluorescence (TADF) feature is extremely limited so far, and it is necessary to expand the candidate pool of excellent red/deep-red emitters. However, how to control the energy level alignment of the 1CT (singlet charge transfer) state and the 3LE (triplet local excitation) state to improve the emission efficiency of materials remains a challenge. Herein, based on our previously reported green fluorescent material 67dTPA-FQ, three new donor-acceptor type TADF materials (TQ-oMeOTPA, TsQ-oMeOTPA and SQ-oMeOTPA) were designed by introducing 4,4'-dimethoxy triphenylamine (MeOTPA) as the donor, and introduced S atoms on the acceptors to enhance the spin-orbit coupling (SOC) and CT effects. The theoretical calculations showed that the newly introduced MeOTPA and S atom successfully enhanced the CT effect of the materials, not only shifting the luminescence peak to the deep red region but also effectively adjusting the energy level alignment of the excited state, accelerating the reverse intersystem crossing process. Finally, the organic light-emitting diodes based on SQ-oMeOTPA exhibit an external quantum efficiency of 19.1%, with an emission peak at 619 nm. This work not only expands the candidate inventory of red TADF materials, but also proves the feasibility of designing emitters by adjusting the excited state energy levels, greatly broadening the diversity of TADF emitters in design, and providing a powerful means for rapidly screening efficient emitters in the future.

Untargeted metabolomic analysis of the metabolites in roots of Pugionium cornutum seedlings under drought stress.

Pugionium cornutum is an annual or biennial xerophyte distributed in arid regions, with drought resistance properties. While previous studies have predominantly focused on the physiological changes of P. cornutum , the understanding of its metabolite variations remains limited. In this study, untargeted metabolomic technology was performed to analyse the change of metabolites in the roots of P. cornutum seedlings under drought stress. Our findings revealed that compared to the R1, the root water potential and the number of lateral roots increased, while the length of the tap root and fresh weight increased first and then decreased. In the R1-R2, a total of 45 differential metabolites (DMs) were identified, whereas in the R1-R3 82 DMs were observed. Subsequently, KEGG analysis revealed a significant enrichment of microbial metabolism in diverse environments and aminobenzoate degradation in the R1-R2, and phenylpropanoid biosynthesis, ubiquinone, and other terpenoid-quinone biosynthesis and isoquinoline alkaloid biosynthesis were significantly enriched in the R1-R3. The upregulation DMs, including L-arginosuccinate, L-tyrosine, p-coumarate, caffeate, ferulate, vanillin, coniferin, 5-aminopentanoate, 2-methylmaleate and 2-furoate in P. cornutum seedlings may play a crucial role in enhancing root growth and improving drought resistance. These findings provide a basis for future investigations into the underlying mechanisms of drought resistance in P. cornutum .

Partial Ligand Stripping from CsPbBr3 Nanocrystals Improves Their Performance in Light-Emitting Diodes.

Halide perovskite nanocrystals (NCs), specifically CsPbBr3, have attracted considerable interest due to their remarkable optical properties for optoelectronic devices. To achieve high-efficiency light-emitting diodes (LEDs) based on CsPbBr3 nanocrystals (NCs), it is crucial to optimize both their photoluminescence quantum yield (PLQY) and carrier transport properties when they are deposited to form films on substrates. While the exchange of native ligands with didodecyl dimethylammonium bromide (DDAB) ligand pairs has been successful in boosting their PLQY, dense DDAB coverage on the surface of NCs should impede carrier transport and limit device efficiency. Following our previous work, here, we use oleyl phosphonic acid (OLPA) as a selective stripping agent to remove a fraction of DDAB from the NC surface and demonstrate that such stripping enhances carrier transport while maintaining a high PLQY. Through systematic optimization of OLPA dosage, we significantly improve the performance of CsPbBr3 LEDs, achieving a maximum external quantum efficiency (EQE) of 15.1% at 516 nm and a maximum brightness of 5931 cd m-2. These findings underscore the potential of controlled ligand stripping to enhance the performance of CsPbBr3 NC-based optoelectronic devices.

Optimizing the Buried Interface in Flexible Perovskite Solar Cells to Achieve Over 24% Efficiency and Long-Term Stability.

The buried interface of the perovskite layer has a profound influence on its film morphology, defect formation, and aging resistance from the outset, therefore, significantly affects the film quality and device performance of derived perovskite solar cells. Especially for FAPbI3 , although it has excellent optoelectronic properties, the spontaneous transition from the black perovskite phase to nonperovskite phase tends to start from the buried interface at the early stage of film formation then further propagate to degrade the whole perovskite. In this work, by introducing ─NH3 + rich proline hydrochloride (PF) with a conjugated rigid structure as a versatile medium for buried interface, it not only provides a solid α-phase FAPbI3 template, but also prevents the phase transition induced degradation. PF also acts as an effective interfacial stress reliever to enhance both efficiency and stability of flexible solar cells. Consequently, a champion efficiency of 24.61% (certified 23.51%) can be achieved, which is the highest efficiency among all reported values for flexible perovskite solar cells. Besides, devices demonstrate excellent shelf-life/light soaking stability (advanced level of ISOS stability protocols) and mechanical stability.

Stepwise-Process-Controlled Ligand Management Strategy for Efficient and Stable Perovskite Quantum Dot Solar Cells.

CsPbI3 perovskite quantum dots (QDs) have attracted much attention in the field of solar cells because of their excellent photovoltaic properties. Conventional modification of long-chain insulating ligands can ensure good dispersion and film-forming stability of QDs, but the limitations of their low defect passivation ability and poor charge transport ability will make them fail to achieve high efficiency in the corresponding solar cell devices. In this study, by introducing "Benzylphosphonic acid" short-chain ligands to the surface of CsPbI3 QDs, the ligands were re-administered on the surface during the preparation of the CsPbI3 QDs as well as during the film-forming process. The strong coordination ability of Benzenephosphonic acid can effectively passivate defects on the surface of CsPbI3 QDs and inhibit non-radiative recombination and phase transition. Meanwhile, this short-chain ligand can effectively promote the charge exchange between adjacent QDs and improve the electrical transport properties of the film. The efficiency of the Benzylphosphonic acid-modified CsPbI3 QDs solar cell reaches 13.91% compared to the unmodified device (PCE of 11.4%). The storage stability and operation stability of the device are also significantly improved. (The efficiency remains at 91% of the original for 800 h of atmospheric storage; the efficiency remains at 92% of the original for 200 h of continuous light exposure.) The present strategy realizes the simultaneous improvement of photovoltaic properties and stability of CsPbI3 QD solar cells and also provides a reference for surface ligand engineering to realize highly efficient and stable perovskite quantum dot solar cells.

Tailoring D-π-A architectures with hybridized local and charge transfer fluorophores exhibiting high electroluminescence exciton utilization and low threshold amplified spontaneous emission.

Novel amorphous compounds which could simultaneously use 25% singlet excitons and 75% triplet excitons as the energy source for light amplification enable the reduction of the threshold current density for electrically pumped organic semiconductor laser diodes (OSLDs); however, there is always a trade-off between the high radiative decay rate of the local excited (LE) state that is required for amplified spontaneous emission (ASE) and high exciton utilization benefiting from the charge-transfer (CT) state during electroluminescence (EL). Herein, we have explored a delicate balance to achieve both low ASE threshold and high EL exciton utilization by adopting a carefully tailored hybridized local and charge-transfer (HLCT) molecular design. A series of donor-π-acceptor (D-π-A) molecules (SBz-1, SBz-2 and SBz-3) are synthesized, and the structural change mainly refers to the spatial distance between D and A which could regulate the excited-state character via adjusting the CT length. Notably, the ASE phenomenon with a low threshold (2.97 µJ cm-2) and a high exciton utilization of 57.6% are achieved at the same time for SBz-2 with an appropriate CT length. The results provide guidance for molecular design toward harvesting triplet excitons in organic laser materials.

Multifunctional Short-Chain 2-Thiophenealkylammonium Bromide Ligand-Assisted Perovskite Quantum Dots for Efficient Light-Emitting Diodes.

Lead halide perovskite quantum dots (QDs) have attracted great interest for application in light-emitting diodes (LEDs) due to their high photoluminescence quantum yield (PLQY), solution processability, and high color purity, showing great potential for next-generation full-color display and lighting technologies. Conventional long-chain insulating oleic acid (OA)/oleamine (OAm) ligands exhibit dynamic binding to the surface of QDs, resulting in a plethora of extra surface defects and inferior optoelectronic properties. Herein, a sole multifunctional ligand with optimized carbon chain length, that is, 2-thiophenepropylamine bromide (ThPABr), was creatively designed and introduced into CsPbBr3 QDs, which not only replaces OAm and provides a bromine source but also coordinates with the uncoordinated surface Pb2+ of QDs through the thiophene, passivating surface defects and increasing the PLQY of the film to 83%. More importantly, the interaction between the electron donor-thiophene ring and QDs can enhance electron injection and improve carrier balance. The resulting green LED exhibited significant performance improvement, showing ultrahigh spectral stability under high operating voltage, achieving a maximum external quantum efficiency of 10.5%, and extending the operating lifetime to 5-fold that of the reference. Designing a single multifunctional ligand presents a promising and convenient strategy for selecting surface ligands that can enhance the performance of LEDs or other optoelectronic devices.

Ligand Engineering in Tin-Based Perovskite Solar Cells.

Perovskite solar cells (PSCs) have attracted aggressive attention in the photovoltaic field in light of the rapid increasing power conversion efficiency. However, their large-scale application and commercialization are limited by the toxicity issue of lead (Pb). Among all the lead-free perovskites, tin (Sn)-based perovskites have shown potential due to their low toxicity, ideal bandgap structure, high carrier mobility, and long hot carrier lifetime. Great progress of Sn-based PSCs has been realized in recent years, and the certified efficiency has now reached over 14%. Nevertheless, this record still falls far behind the theoretical calculations. This is likely due to the uncontrolled nucleation states and pronounced Sn (IV) vacancies. With insights into the methodologies resolving both issues, ligand engineering-assisted perovskite film fabrication dictates the state-of-the-art Sn-based PSCs. Herein, we summarize the role of ligand engineering during each state of film fabrication, ranging from the starting precursors to the ending fabricated bulks. The incorporation of ligands to suppress Sn2+ oxidation, passivate bulk defects, optimize crystal orientation, and improve stability is discussed, respectively. Finally, the remained challenges and perspectives toward advancing the performance of Sn-based PSCs are presented. We expect this review can draw a clear roadmap to facilitate Sn-based PSCs via ligand engineering.

PtII(C

A series of four-coordinated PtII(C^N)(N-donor ligand)Cl-type complexes have been synthesized through a combination of long-size C^N-type and N-donor ligands. In addition, by varying the coordinating site in the N-donor ligand, a distorted molecular configuration has been constructed in these complexes. Their photophysical features, aggregation-induced phosphorescence emission (AIPE) behaviors, electrochemical properties and electroluminescence (EL) performance have been investigated in detail. It has been found that their AIE behaviors can be enhanced by both employing long-size ligands, especially the N-donor ligand, and adopting a distorted molecular configuration, furnishing a high AIE factor (αAIE) of ca. 13.8. Critically, benefitting from their long-size C^N-type and N-donor ligands, these PtII(C^N)(N-donor ligand)Cl-type complexes can exhibit very sensitive AIE behaviors in a mixture of THF-H2O, indicated by their noticeable emission increase with a low H2O volumetric fraction (fw) of ca. 0.1 in their THF solution. In solution-processed organic light-emitting diodes (OLEDs), they can achieve a luminance of 6743 cd m-2 at 13.5 V, a maximum external quantum efficiency (ηext) of 13.8%, a maximum current efficiency (ηL) of 42.4 cd A-1 and a maximum power efficiency (ηP) of 34.4 lm W-1, respectively. Hence, this research can provide key information for developing phosphorescent complexes with a highly sensitive AIE response and impressive EL ability.

m6A methylation regulates hypoxia-induced pancreatic cancer glycolytic metabolism through ALKBH5-HDAC4-HIF1α positive feedback loop.

Pancreatic cancer (PC) is the most hypoxic cancer type among solid tumors. The dynamic changes of RNA N6-methyl-adenosine (m6A) contribute to tumor cells adaption to hypoxic microenvironmental. However, the regulatory mechanisms of hypoxia response in PC remains elusive. Here, we reported that the m6A demethylase ALKBH5 mediated a decrease of total mRNA m6A modification during hypoxia. Subsequently, methylated RNA immunoprecipitation sequencing (MeRIP-seq) combined with RNA sequencing (RNA-seq) revealed transcriptome-wide gene expression alteration and identified histone deacetylase type 4 (HDAC4) as a key target gene of m6A modification under hypoxic conditionds. Mechanistically, m6A methylation recognized by m6A reader-YTHDF2 enhanced the stability of HDAC4, and then promoted glycolytic metabolism and migration of PC cells. Our assays also demonstrated that hypoxia-induced HDAC4 enhanced HIF1a protein stability, and overexpressed HIF1a promoted transcription of ALKBH5 in hypoxic pancreatic cancer cells. Together, these results found a ALKBH5/HDAC4/HIF1α positive feedback loop for cellular response to hypoxia in pancreatic cancer. Our studies uncover the crosstalk between histone acetylation and RNA methylation modification on layer of epigenetic regulation.

Understanding the response in Pugionium cornutum (L.) Gaertn. seedling leaves under drought stress using transcriptome and proteome integrated analysis.

Background: Drought is one of the crucial constraints limiting horticultural plant's production and development around the world. Pugionium cornutum is an annual or biennial xerophyte with strong environmental adaptability and drought resistance; however, the mechanisms with respect to response to drought stress remain largely unclear. Methods: After seedling emergence, the gravimetric method was used to control soil relative water content (SRWC). Drought stress was applied to the six-leaf stage P. cornutum seedlings. The soil water content of different drought stress levels (L) was controlled by gravimetric method as follows: control (L1): 70-75% SRWC; moderate drought level (L2): 40-45% SRWC; severe drought level (L3): 30-35% SRWC, and the water was added to different drought stress levels at about 18:00 p.m. every day. The experiment ended when the leaves of P. cornutum showed severe wilting (10-leaf stage). Samples were harvested and stored at -80 °C for physiological determination, and transcriptomic and proteomic sequencing. Results: Compared with L1, the leaves of P. cornutum seedlings were increasingly wilted after drought treatment; the SRWC of the drought-stress leaves decreased notably while the leaf water potential was rose; the proline, malondialdehyde (MDA) content increased with the continuous drought treatment but peroxidase (POD) activity decreased. Besides, 3,027 differential genes (DGs) and 196 differential proteins (DPs), along with 1,943 DGs and 489 DPs were identified in L2-L1 and L3-L1, respectively. The transcriptome and proteome integrated analysis manifested that only 30 and 70 were commonly regulated both in L2-L1 and L3-L1, respectively. Of which, 24 and 61 DGs or DPs showed the same trend including sHSPs, APX2, GSTU4, CML42, and POD, etc. However, most of DGs or DPs were regulated only at the transcriptome or proteome level mainly including genes encoding signal pathway (PYR1, PYLs, SnRK2J, PLC2, CDPK9/16/29, CML9, MAPKs), transcription factors (WRKYs, DREB2A, NAC055, NAC072, MYB and, HB7) and ion channel transporters (ALMT4, NHX1, NHX2 and TPK2). These genes or proteins were involved in multiple signaling pathways and some important metabolism processes, which offers valuable information on drought-responsive genes and proteins for further study in P. cornutum.

Pharmacokinetics and Bioequivalence of Abiraterone Acetate Tablets in Healthy Chinese Volunteers: An Open, Randomized, Single-Dose, Three-Period, Three-Sequence Crossover Study.

BACKGROUND AND OBJECTIVE: Abiraterone acetate tablet is an inhibitor of androgen synthesis, primarily for the treatment of metastatic castration-resistant prostate cancer (mCRPC). This study evaluated the bioequivalence and pharmacokinetics of the reference and test formulations of abiraterone acetate tablets in healthy Chinese volunteers. METHODS: A single-center, open, single-dose, randomized, three-period, three-sequence, semi-repeat (only repeated reference formulations), and reference formulation-corrected fasting reference-scaled average bioequivalence test was conducted in 36 healthy volunteers included in this study. Volunteers were randomly assigned to one of three groups in a 1:1:1 ratio. There was a minimum 7-day washout period between each dose. Blood samples were collected at prescribed time intervals, the plasma concentration of abiraterone acetate tablets was determined by liquid chromatography-tandem mass spectrometry, and adverse events were recorded. RESULTS: Under fasting conditions, the maximum plasma concentration (Cmax) was 27.02 ± 14.21 ng/mL, area under the concentration-time curve from time zero to time t (AUCt) was 125.30 ± 82.41 h·ng/mL, and AUC from time zero to infinity (AUC∞) was 133.70 ± 83.99 h·ng/mL. The 90% confidence intervals (CIs) of the geometric mean ratio (GMR) of AUCt and AUC∞ were in the range of 0.8000-1.2500, and the coefficient of variation (CVWR) of Cmax was more than 30%. The Critbound result was - 0.0522, and the GMR was between 0.8000 and 1.2500. CONCLUSION: Both test and reference formulations of abiraterone acetate tablets were bioequivalent in healthy Chinese subjects under fasting conditions. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT04863105, registered 26 April 2021-retrospectively registered ( https://register. CLINICALTRIALS: gov/prs/app/action/SelectProtocol?sid=S000ARAA&selectaction=Edit&uid=U00050YQ&ts=2&cx=-vbtjri.

Perspectives for the conversion of perovskite indoor photovoltaics into IoT reality.

As a competitive candidate for powering low-power terminals in Internet of Things (IoT) systems, indoor photovoltaic (IPV) technology has attracted much attention due to its effective power output under indoor light illumination. One such emerging photovoltaic technology, perovskite cell, has become a hot topic in the field of IPVs due to its outstanding theoretical performance limits and low manufacturing costs. However, several elusive issues remain limiting their applications. In this review, the challenges for perovskite IPVs are discussed in view of the bandgap tailoring to match indoor light spectra and the defect trapping regulation throughout the devices. Then, we summarize up-to-date perovskite cells, highlighting advanced strategies such as bandgap engineering, film engineering and interface engineering to enhance indoor performance. The investigation of indoor applications of large and flexible perovskite cells and integrated devices powered by perovskite cells is exhibited. Finally, the perspectives for the perovskite IPV field are provided to help facilitate the further improvement of indoor performance.

Harvesting the Triplet Excitons of Quasi-Two-Dimensional Perovskite toward Highly Efficient White Light-Emitting Diodes.

Utilization of triplet excitons, which generally emit poorly, is always fundamental to realize highly efficient organic light-emitting diodes (LEDs). While triplet harvest and energy transfer via electron exchange between triplet donor and acceptor are fully understood in doped organic phosphorescence and delayed fluorescence systems, the utilization and energy transfer of triplet excitons in quasi-two-dimensional (quasi-2D) perovskite are still ambiguous. Here, we use an orange-phosphorescence-emitting ultrathin organic layer to probe triplet behavior in the sky-blue-emitting quasi-2D perovskite. The delicate white LED architecture enables a carefully tailored Dexter-like energy-transfer mode that largely harvests the triplet excitons in quasi-2D perovskite. Our white organic-inorganic LEDs achieve maximum forward-viewing external quantum efficiency of 8.6% and luminance over 15 000 cd m-2, exhibiting a significant efficiency enhancement versus the corresponding sky-blue perovskite LED (4.6%). The efficient management of energy transfer between excitons in quasi-2D perovskite and Frenkel excitons in the organic layer opens the door to fully utilizing excitons for white organic-inorganic LEDs.

Complementary Triple-Ligand Engineering Approach to Methylamine Lead Bromide Nanocrystals for High-Performance Light-Emitting Diodes.

Conjugated and short-molecule capping ligands have been demonstrated as a valid strategy for achieving high-efficiency perovskite nanocrystal (NCs) light-emitting diodes (LEDs) owing to their advantage of allowing efficient carrier transport between NCs. However, monotonously utilizing conjugated ligands cannot achieve sufficient surface modification/passivation for perovskite NCs, leading to their poor photoluminescence quantum yield (PLQY) and dispersibility. This work designs a complementary ligand synthesis method to obtain high-quality methylamine lead bromide (MAPbBr3) NCs and then leverage them into efficient LEDs. The complementary ligand system combines a conjugated ligand 3-phenyl-2-propen-1-amine (PPA) and a long-chain ligand didodecyldimethylammonium bromide (DDAB) together with a well-known inductive inorganic ligand ZnBr2. With such complementary ligand engineering, we significantly improve the emissive features of MAPbBr3 NCs (PLQY: 99% ± 0.7%). Simultaneously, the complementary ligand strategy facilitated the adequate charge transportation in related NCs films and modified the interfacial energy-level alignment when the NCs assemble as an emitting layer into LEDs. Finally, based on this NCs synthesis method, high-efficiency green LEDs were achieved, exhibiting the maximum luminance of 1.59 × 104 cd m-2, a current efficiency of 23.7 cd A-1, and an external quantum efficiency of 7.8%. Our finding could provide a new avenue for further development of LEDs and their commercial application.

Hole Transport Layer Free Perovskite Light-Emitting Diodes With High-Brightness and Air-Stability Based on Solution-Processed CsPbBr3-Cs4PbBr6 Composites Films.

Recently, perovskite light-emitting diodes (PeLEDs) have drew widespread attention due to their high efficiencies. However, because of the sensitivity to moisture and oxygen, perovskite luminescent layers are usually prepared in high-purity nitrogen environment, which increases the cost and process complexity of device preparation and seriously hindrances its commercialization of PeLED in lighting and display application. Herein, dual-phase all-inorganic composite CsPbBr3-Cs4PbBr6 films are fabricated from CsBr-rich perovskite solutions by a simple one-step spin-coating method in the air with high humidity. Compared with the pure CsPbBr3 film, the composite CsPbBr3-Cs4PbBr6 film has much stronger photoluminescence emission and longer fluorescence lifetime, accompanied by increased photoluminescence quantum yield (33%). As a result, we obtained green PeLED devices without hole transport layer exhibiting a maximum brightness of 72,082 cd/m2 and a maximum external quantum efficiency of about 2.45%, respectively. More importantly, the champion device shows excellent stability with operational half-lifetime exceeding 1,000 min under continuous operation in the air. The dual-phase all-inorganic composite CsPbBr3-Cs4PbBr6 film shows attractive prospect for advanced light emission applications.

Highly efficient and stable perovskite solar cells enabled by low-dimensional perovskitoids.

Deep traps originated from the defects formed at the surfaces and grain boundaries of the perovskite absorbers during their lattice assembly are the main reasons that cause nonradiative recombination and material degradation, which notably affect efficiency and stability of perovskite solar cells (PSCs). Here, we demonstrate the substantially improved PSC performance by capping the photoactive layer with low-dimensional (LD) perovskitoids. The undercoordinated Pb ions and metallic Pb at the surfaces of the three-dimensional (3D) perovskite are effectively passivated via the Pb-I bonding from the favorably lattice-matched 3D/LD interface. The good stability and hydrophobicity of the LD (0D and 1D) perovskitoids allow excellent protection of the 3D active layer under severe environmental conditions. The PSC exhibits a power conversion efficiency of 24.18%, reproduced in an accredited independent photovoltaic testing laboratory. The unencapsulated device maintains 90% of its initial efficiency after 800 hours of continuous illumination under maximum power point operating conditions.

High Triplet Energy Level Molecule Enables Highly Efficient Sky-Blue Perovskite Light-Emitting Diodes.

The role of triplet states in the interfacial energy transfer in perovskite light-emitting diodes (PeLEDs) has so far not been clarified because of the complex exciton recombination and decay dynamics. This work aims to study this issue and accordingly proposes a novel interfacial-engineering strategy for efficient sky-blue PeLEDs. To this end, bis[2-(diphenylphosphino)phenyl]ether oxide with a high triplet energy level is introduced into sky-blue PeLEDs. It effectively reduces undesirable exciton transfer from the perovskite emission layer to the electron-transport layer, largely suppresses exciton quenching at the interface, and simultaneously passivates defects at the perovskite surfaces. As a result of the multichannel energy-loss reduction, sky-blue PeLED that emits at 488 nm is achieved with a peak external quantum efficiency of 10.17% and a maximum brightness of 6728.41 cd m-2. This work thus provides indirect evidence for the triplet mechanism of blue emission of mixed-halide perovskites and sheds new light on a promising way of boosting the performance of blue PeLEDs.

Cohesively Enhancing the Conductance, Mechanical Robustness, and Environmental Stability of Random Metallic Mesh Electrodes via Hot-Pressing-Induced In-Plane Configuration.

Flexible transparent conductive electrode (FTCE) is highly desirable due to the fast-growing flexible optoelectronic devices. Several promising FTCEs based on metal material have been developed to replace conventional indium tin oxide (ITO). The random metal mesh is considered to be one of the competitive candidates. However, obtaining feasible random metal mesh with low sheet resistance, high transparency, good mechanical durability, and strong environmental stability is still a great challenge. Here, a random metal mesh-based FTCE with an in-plane structure, achieved by a facile hot-pressing process, is demonstrated. The hot-pressing process enables the fabrication of highly conductive FTCE with improved mechanical robustness and environmental stability. The in-plane FTCE shows a low sheet resistance of 1.63 Ω·sq-1 with an 80.6% transmittance, low relative resistance increase (RRI) of 7.9% after 240 h 85 °C/85% RH test, and low RRI of 8.0% after 105 cycles of bending test. Besides, various applications of the in-plane FTCE were demonstrated, including the flexible heater, flexible touch screen, and flexible electroluminescence. We anticipate that these results will spark interest in in-plane random metal mesh electrodes and enable the application of random metal mesh in flexible optoelectronic devices.