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Abstract Three novel asymmetric Ir(III) complexes have been rationally designed to optimize their emitting dipole orientations (EDO) and enhance light outcoupling in blue phosphorescent organic light‐emitting diodes (OLEDs), thereby boosting their external quantum efficiency (EQE). Bulky electron‐donating groups (EDGs), namely: carbazole (Cz), di‐tert‐butyl carbazole (tBuCz), and phenoxazine (Pxz) are incorporated into the tridentate dicarbene pincer chelate to induce high degree of packing anisotropy, simultaneously enhancing their photophysical properties. Angle‐dependent photoluminescence (ADPL) measurements indicate increased horizontal transition dipole ratios of 0.89 and 0.90 for the Ir(III) complexes Cz‐dfppy‐CN and tBuCz‐dfppy‐CN, respectively. Analysis of the single crystal structure and density functional theory (DFT) calculation results revealed an inherent correlation between molecular aspect ratio and EDO. Utilizing the newly obtained emitters, the blue OLED devices demonstrated exceptional performance, achieving a maximum EQE of 30.7% at a Commission International de l'Eclairage (CIE) coordinate of (0.140, 0.148). Optical transfer matrix‐based simulations confirmed a maximum outcoupling efficiency of 35% due to improved EDO. Finally, the tandem OLED and hyper‐OLED devices exhibited a maximum EQE of 44.2% and 31.6%, respectively, together with good device stability. This rational molecular design provides straightforward guidelines to reach highly efficient and stable saturated blue emission.

Abstract Regulating electron transport rate and ion concentrations in the local microenvironment of active site can overcome the slow kinetics and unfavorable thermodynamics of CO2 electroreduction. However, simultaneous optimization of both kinetics and thermodynamics is hindered by synthetic constraints and poor mechanistic understanding. Here we leverage laser-assisted manufacturing for synthesizing CuxO bipyramids with controlled tip angles and abundant nanograins, and elucidate the mechanism of the relationship between electron transport/ion concentrations and electrocatalytic performance. Potassium/OH− adsorption tests and finite element simulations corroborate the contributions from strong electric field at the sharp tip. In situ Fourier transform infrared spectrometry and differential electrochemical mass spectrometry unveil the dynamic evolution of critical *CO/*OCCOH intermediates and product profiles, complemented with theoretical calculations that elucidate the thermodynamic contributions from improved coupling at the Cu+/Cu2+ interfaces. Through modulating the electron transport and ion concentrations, we achieve high Faradaic efficiency of 81% at ~900 mA cm−2 for C2+ products via CO2RR. Similar enhancement is also observed for nitrate reduction reaction (NITRR), achieving 81.83 mg h−1 ammonia yield rate per milligram catalyst. Coupling the CO2RR and NITRR systems demonstrates the potential for valorizing flue gases and nitrate wastes, which suggests a practical approach for carbon-nitrogen cycling.

Abstract The realization of operationally stable blue organic light-emitting diodes is a challenging issue across the field. While device optimization has been a focus to effectively prolong device lifetime, strategies based on molecular engineering of chemical structures, particularly at the subatomic level, remains little. Herein, we explore the effect of targeted deuteration on donor and/or acceptor units of thermally activated delayed fluorescence emitters and investigate the structure-property relationship between intrinsic molecular stability, based on isotopic effect, and device operational stability. We show that the deuteration of the acceptor unit is critical to enhance the photostability of thermally activated delayed fluorescence compounds and hence device lifetime in addition to that of the donor units, which is commonly neglected due to the limited availability and synthetic complexity of deuterated acceptors. Based on these isotopic analogues, we observe a gradual increase in the device operational stability and achieve the long-lifetime time to 90% of the initial luminance of 23.4 h at the luminance of 1000 cd m−2 for thermally activated delayed fluorescence-sensitized organic light-emitting diodes. We anticipate our strategic deuteration approach provides insights and demonstrates the importance on structural modification materials at a subatomic level towards prolonging the device operational stability.

Abstract Luminescent chromophores armed with aggregation‐induced emission (AIE) characteristics can switch their fluorescence sensing by manipulating the aggregation and disaggregation states, leading to high sensitivity and high signal‐to‐noise ratio sensors. Accordingly, aggregation‐induced emission luminogens (AIEgens) have been widely applied to various biosensing, one of which is the gas sensors. Due to the weak signal, easy diffusion, difficult capture, and instability of gas molecules, electrochemical or infrared tests are generally used for detection. However, electrochemical tests have high power consumption, and the environment easily disturbs infrared tests. Fortunately, photochemical sensors utilizing AIE properties can effectively overcome these deficiencies. AIEgens usually exhibit large Stokes shift, good photostability, and low random blinking, suggesting excellent sensing reproducibility and many achievements have been obtained in AIEgens‐based gas sensors. This review summarizes the gas detection mechanism of AIEgens, and enumerate the reported gas sensors based on AIEgens. Then a perspective on the field and challenges facing it are elaborated so that researchers can better understand the development status of this field and develop more AIE‐type spectroscopic probes with gas‐responsive functions. It is expected to greatly enrich the types of gas sensors and promote the development of the application of AIE properties.

Abstract Organic near‐infrared (NIR) photodetectors with essential applications in medical diagnostics, night vision, remote sensing, and optical communications have attracted intensive research interest. Compared with most conventional inorganic counterparts, organic semiconductors usually have higher absorption coefficients, and their thin active layer could be sufficient to absorb most incident light for effective photogeneration. However, due to the relatively poor charge mobility of organic materials, it remains challenging to inhibit the photogenerated exciton recombination and effectively extract carriers to their respective electrodes. Herein, this challenge was addressed by increasing matrix conductivities of a ternary active layer (D–A–D structure NIR absorber [2TT‐oC6B]:poly(N,N′‐bis‐4‐butylphenyl‐N,N′‐bisphenyl)benzidin [PolyTPD]:[6,6]‐phenyl‐C61‐butyric acid methyl ester [PCBM] = 1:1:1) upon in situ incident light illumination, significantly accelerating charge transport through percolated interpenetrating paths. The greatly enhanced photoconductivity under illumination is intrinsically related to the unique donor–acceptor molecular structures of PolyTPD and 2TT‐oC6B, whereas stable intermolecular interaction has been verified by systematic molecular dynamics simulation. In addition, an ultrafast charge transfer time of 0.56 ps from the NIR aggregation‐induced luminogens of 2TT‐oC6B absorber to PolyTPD and PCBM measured by femtosecond transient absorption spectroscopy is beneficial for effective exciton dissociation. The solution‐processed organic NIR photodetector exhibits a fast response time of 83 μs and a linear dynamic range value of 111 dB under illumination of 830 nm. Therefore, our work has opened up a pioneering window to enhance photoconductivity through in situ photoirradiation and benefit NIR photodetectors as well as other optoelectronic devices.

Abstract Two newly designed and synthesized [3+2+1] iridium complexes through introducing bulky trimethylsiliyl (TMS) groups are doped with a terminal emitter of v–DABNA to form an coincident overlapping spectra between the emission of these two phosphors and the absorption of v–DABNA, creating cascade resonant energy transfer for efficient triplet harvesting. To boost the color quality and efficiency, the fabricated hyper‐OLEDs have been optimized to achieve a high external quantum efficiency of 31.06%, which has been among the highest efficiency results reported for phosphor sensitized saturated‐blue hyper‐OLEDs, and pure blue emission peak at 467 nm with the full width at half maxima (FWHM) as narrow as 18 nm and the CIEy values down to 0.097, satisfying the National Institute of Standards and Technology (NIST) requirement for saturated blue OLEDs display. Surprisingly, such hyper‐OLEDs have obtained the converted lifetime (LT50) up to 4552 h at the brightness of 100 cd m−2, demonstrating effective Förster resonance energy transfer (FRET) process. Therefore, employing these new bulky TMS substituent [3+2+1] iridium(III) complexes for effective sensitizers can greatly pave the way for further development of high efficiency and stable blue OLEDs in display and lighting applications.

Abstract The 2D MoS2 with superior optoelectronic properties such as high charge mobility and broadband photoresponse has attracted broad research interests in photodetectors (PD). However, due to the atomic thin layer of 2D MoS2, its pure photodetectors usually suffer from inevitable drawbacks such as large dark current, and intrinsically slow response time. Herein, a new organic material BTP‐4F with high mobility is successfully stacked with 2D MoS2 film to form an integrated 2D MoS2/organic P–N heterojunction, facilitating efficient charge transfer as well as significantly suppressed dark current. As a result, the as‐obtained 2D MoS2/organic (PD) has exhibited excellent response and fast response time of 332/274 µs. The analysis validated photogenerated electron transition from this monolayer MoS2 to subsequent BTP‐4F film, whereas the transited electron is originated from the A− exciton of 2D MoS2 by temperature‐dependent photoluminescent analysis. The ultrafast charge transfer time of ≈0.24 ps measured by time‐resolved transient absorption spectrum is beneficial for efficient electron–hole pair separation, greatly contributing to the obtained fast photoresponse time of 332/274 µs. This work can open a promising window to acquire low‐cost and high‐speed (PD).

Abstract Solution processable quasi‐2D (Q‐2D) perovskite materials are emerging as a promising candidate for blue light source in full‐color display applications due to their good color saturation property, high brightness, and spectral tunability. Herein, an efficient energy cascade channel is developed by introducing sodium bromide (NaBr) in phenyl‐butylammonium (PBA)‐containing mixed‐halide Q‐2D perovskites for a blue perovskite light‐emitting diode (PeLED). The incorporation of alkali metal contributes to the nucleation and growth of Q‐2D perovskites into graded distribution of domains with different layer number . The study of excitation dynamics by transient absorption (TA) spectroscopy confirms that NaBr induces more Q‐2D perovskite phases with small n number, providing a graded energy cascade pathway to facilitate more efficient energy transfer processes. In addition, the nonradiative recombination within the Q‐2D perovskites is significantly suppressed upon Na+ incorporation, as validated by the trap density estimation. Consequently, the optimized blue PeLEDs manifest a peak external quantum efficiency (EQE) of 7.0% emitting at 486 nm with a maximum luminance of 1699 cd m−2. It is anticipated that these findings will improve the understanding of alkali‐metal‐assisted optimization of Q‐2D perovskites and pave the way toward high‐performance blue PeLEDs.

It remains urgent to integrate conductive InSb colloidal quantum dots (CQDs) for sensitive and fast near‐infrared (NIR) photodetection applications. Herein, nanocrystallized InSb CQDs (

It remains challenging to fabricate high‐efficiency all‐inorganic perovskite solar cells (PSCs) at low temperature. Herein, the low‐temperature preparation of high‐efficiency CsPbI3 PSCs using hydroiodic acid (HI) and deionized water (H2O) as additives at synthetic temperature as low as 100 °C is proposed, which is beneficial for constructing even more complicated tandem or flexible solar cells. The additive of HI facilitates CsPbI3 to form a high‐quality and smooth perovskite film at low temperature. The addition of an optimal amount of H2O further induces perovskite growth with larger grains and a smoother surface by the dissolution and recrystallization process in the grain boundary, which can suppress defects‐induced nonradiative recombination. In this scenario, the corresponding device with structure of ITO/PEDOT:PSS/CsPbI3/PC61BM/Ag exhibits a high power conversion efficiency of 11.41% and the fill factor is increased from 62% to about 69%, compared with device based on CsPbI3 film without extra H2O treatment. The appropriate amount of H2O promotes the high‐quality multigrain growth of the CsPbI3 film and reduces the internal defects, contributing to a significant improved charge collection efficiency. Therefore, this research work has paved a significant way to improving the quality of the all‐inorganic perovskite film for highly efficient solar cells.

Cyclometalated iridium (III) complexes are indispensable in the field of phosphorescent organic light-emitting diodes (PhOLEDs), while the improvement of blue iridium (III) complexes is as yet limited and challenging. More diversified blue emitters are needed to break through the bottleneck of the industry. Hence, a novel [3+2+1] coordinated iridium (III) complex (noted as Ir-dfpMepy-CN) bearing tridentate bis-N-heterocyclic carbene (NHC) chelate (2,6-bisimidazolylidene benzene), bidentate chelates 2-(2,4-difluorophenyl)-4-methylpyridine (dfpMepy), and monodentate ligand (-CN) has been designed and synthesized. The tridentate bis-NHC ligand enhances molecular stability by forming strong bonds with the center iridium atom. The electron-withdrawing groups in the bidentate ligand (dfpMepy) and monodentate ligand (-CN) ameliorate the stability of the HOMO levels. Ir-dfpMepy-CN shows photoluminescence peaks of 440 and 466 nm with a high quantum efficiency of 84 ± 5%. Additionally, the HATCN (10 nm)/TAPC (40 nm)/TcTa (10 nm)/10 wt% Ir-dfpMepy-CN in DPEPO (10 nm)/TmPyPB (40 nm)/Liq (2.5 nm)/Al (100 nm) OLED device employing the complex shows a CIE coordinate of (0.16, 0.17), reaching a deeper blue emission. The high quantum efficiency is attributed to rapid singlet to triplet charge transfer transition of 0.9–1.2 ps. The successful synthesis of Ir-dfpMepy-CN has opened a new window to develop advanced blue emitters and dopant alternatives for future efficient blue PhOLEDs.

Summary: Interfacial instability between solid electrolytes (SEs) and lithium metal remains a daunting challenge for solid-sate batteries. Here, a conformal C60 interlayer is efficiently constructed on Li1.5Al0.5Ge1.5(PO4)3 (LAGP) SEs by physical vapor deposition, and an ideal interfacial contact is achieved via forming an ionically conducting matrix of LixC60 with lithium metal. The obtained LixC60 is beneficial to hinder the growth of lithium dendrites at interface and release the local stress during the lithiation and delithiation. As a result, the Li/LAGP-C60/Li symmetric cells demonstrate ultra-stable cycling performance for more than 4,500 h at a current density of 0.034 mA cm−2. The Li/LAGP-C60/LiFePO4 full cells deliver a reversible capacity of 152.4 mAh g−1 at room temperature, and the capacity retention rate is 85% after more than 100 cycles. This work provides a feasible and scalable strategy to improve the SEs/Li interface for high-performance solid-state batteries.

Monolayer tungsten disulfide (2D WS2) films have attracted tremendous interest due to their unique electronic and optoelectronic properties. However, the controlled growth of monolayer WS2 is still challenging. In this paper, we report a novel method to grow WS2 through chemical vapor deposition (CVD) with ZnO crystalline whisker as a growth promoter, where partially evaporated WS2 reacts with ZnO to form ZnWO4 by-product. As a result, a depletion region of W atoms and S-rich region is formed which is favorable for subsequent monolayer growth of WS2, selectively positioned on the silicon oxide substrate after the CVD growth.

The forthcoming wireless networks must integrate to a high density of end-user devices while ensuring a superior quality of service. It is imperative to devise solutions that reduce the density of wireless access points and associated costs, while simultaneously ensuring security and privacy throughout propagation. Herein, a novel dual-band photodetector with high selective responsivities in distinct visible and near-infrared (NIR) band is developed as an optical signal receiver. The receiver has an unprecedented fast switch speed > 500 kHz between different operation modes. Leveraging this fast switch speed, a high-speed Multiple-Input-Single-Output (MISO) system is developed, fusing spectrum resources from visible to infrared bands. The system achieves a data rate of 600 Kbps in the visible channel and 500 Kbps in the NIR channel, with a sum rate of 1.1 Mbps. This is the highest single-channel data rate and sum rate among reported dual-band photodetectors. Additionally, two previously overlooked mechanisms, the Subtraction and Addition modes, are studied in detail. The four operation modes are developed to establish a novel physical encryption method in terms of arithmetic relation. The dual-channel coupled link can support a data rate of 200 Kbps, significantly enhancing communication security. [ABSTRACT FROM AUTHOR]

new class of deep-blue phosphorescent [3+2+1] coordinated iridium(III) complexes containing phenyl-3H-imidazo[4,5-b] pyridine-based (CC) bidentate ligands have been synthesized, characterized, and applied as phosphorescent dopants in the fabrication of vacuum-deposited organic light-emitting devices (OLEDs). The manipulation of the relative bulkiness of the CC ligands is the key to control the emission energies in solid-state thin films, ranging from 415 to 470 nm. Taking advantages of the intraligand charge transfer nature of the emissive state, these complexes display short excited-state lifetimes in the sub-nanosecond regime of 0.3 to 1.1 μs, yielding high radiative decay rate constants on the order of up to 106 s-1. High-performance vacuum-deposited deep-blue-emitting OLEDs have been fabricated based on these complexes, demonstrating an external quantum efficiency (EQE) of 11.2% and Commission International de L'Eclairage (CIE (x, y)) coordinates of (0.16, 0.07), making them the deepest blue emitters for this class of new [3+2+1] Ir phosphorescent materials. [ABSTRACT FROM AUTHOR]

Cephalopod (e.g., squid, octopus, etc.) skin is a soft cognitive organ capable of elastic deformation, visualizing, stealth, and camouflaging through complex biological processes of sensing, recognition, neurologic processing, and actuation in a noncentralized, distributed manner. However, none of the existing artificial skin devices have shown distributed neuromorphic processing and cognition capabilities similar to those of a cephalopod skin. Thus, the creation of an elastic, biaxially stretchy device with embedded, distributed neurologic and cognitive functions mimicking a cephalopod skin can play a pivotal role in emerging robotics, wearables, skin prosthetics, bioelectronics, etc. This paper introduces artificial neuromorphic cognitive skins based on arrayed, biaxially stretchable synaptic transistors constructed entirely out of elastomeric materials. Systematic investigation of the synaptic characteristics such as the excitatory postsynaptic current, paired-pulse facilitation index of the biaxially stretchable synaptic transistor under various levels of biaxial mechanical strain sets the operational foundation for stretchy distributed synapse arrays and neuromorphic cognitive skin devices. The biaxially stretchy arrays here achieved neuromorphic cognitive functions, including image memorization, long-term memorization, fault tolerance, programming, and erasing functions under 30% biaxial mechanical strain. The stretchy neuromorphic imaging sensory skin devices showed stable neuromorphic pattern reinforcement performance under both biaxial and nonuniform local deformation. [ABSTRACT FROM AUTHOR]

Squaraine (SQ) dyes are notable for their exceptionally high absorption coefficients extending from the green to the near-infrared. In this work, we utilize the functionalized SQ donor: 2,4-bis [4-(N-phenyl-1-naphthylamino)-2,6-dihydroxyphenyl] squaraine (1-NPSQ) by substitution of isobutylamines in the common “parent SQ” with arylamines to improve stacking and hence exciton and charge transport. The strong electron-withdrawing arylamine group results in a highest occupied molecular orbital energy of 5.3 eV, compared to 5.1 eV for the parent SQ, making 1-NPSQ a suitable donor when used with a C60acceptor in an organic photovoltaic cell. Optimized and thermally annealed, nanocrystalline heterojunction 1-NPSQ/C60/bathocuproine solar cells with an open circuit voltage of 0.90 ± 0.01 V, fill factor of 0.64 ± 0.01, and short circuit current of 10.0 ± 1.1 mA/cm2at 1 sun, AM1.5G illumination (solar spectrally corrected) result in a power conversion efficiency of 5.7 ± 0.6%. Crystallograpnic data suggest that the intermolecular stacking of 1-NPSQ molecules is closer than that of the parent SQ, thereby reducing the device series resistance and increasing its fill factor. [ABSTRACT FROM AUTHOR]

Spin-cast 2,4-bis[4-(N,N-diisobutylamino)-2,6-dihydroxyphenyl]squaraine (SQ) thin films only 62 Å thick are converted from amorphous to polycrystalline via postannealing at elevated temperatures. The surface roughness of the SQ films increases by a factor of 2, while selected area electron diffraction spectra indicate an increase in the extent of postannealed film crystallinity. Dichloromethane solvent annealing is also demonstrated to increase the exciton diffusion length of SQ by a factor of 3 over thermally annealed SQ films as a result of further enhancement in crystalline order. We find that the roughened surface features have a length scale on the order of the exciton diffusion length. Hence, coating the donor SQ with the acceptor, C60, results in a nearly optimum controlled bulk heterojunction solar cell structure. Optimized SQ/C60photovoltaic cells have a power conversion efficiency of ηp= 4.6 ± 0.1% (correcting for solar mismatch) at 1 sun (AM1.5G) simulated solar intensity, and a corresponding peak external quantum efficiency of EQE = 43 ± 1% even for the very thin SQ layers employed. [ABSTRACT FROM AUTHOR]

Power efficiencies >60% have been predicted for idealized quantum dot (QD) intermediate band solar cells. This goal has not yet been realized, due in part to nonidealities that result in charge trapping followed by recombination of photocarriers in the QDs, and the lack of an optimal materials combination. To eliminate charge trapping, a p−i−ncell employing QDs buried within a high band gap barrier layer is proposed and analyzed. The maximum solar power conversion efficiency under AM1.5 spectral radiation of an example GaAs-based photovoltaic cell employing 10−20 layers of InAs QDs surrounded by AlxGa1-xAs barriers in the junction built-in depletion region can be as high as 45%. Higher efficiencies are anticipated for InP-based cells. This represents a significant improvement over GaAs homojunction cells with maximum efficiencies of <25%. [ABSTRACT FROM AUTHOR]