A magic organic molecule assembled capping layer enables airprocessed α-FAPbI_(3) perovskite solar cell with state-of-the-art performances

The black-phase formamidine-lead iodide(α-FAPbI_(3)),boasting an optimal bandgap of 1.5 eV,stands out as a premier choice for narrow-bandgap perovskite solar cells(PSCs),achieving a certified power conversion efficiency(PCE)of 26.1%[1−5].This impressive performance hinges on the orderly and homogeneous crystallization ofα-phase pure FAPbI_(3),facilitated by coordinating solvents such as dimethyl sulfoxide(DMSO)to form intermediates like PbI_(2)-DMSO complex(D-complex).The D-complex plays a pivotal role in crystallization thermodynamics,enabling the direct formation of α-FAPbI_(3) without the photoinactiveδ-phase[6−9].However,DMSO,a commonly used coordinating solvent,is highly hygroscopic and prone to hydration upon moisture exposure.This tendency leads to incomplete perovskite crystallization and accelerates the transformation of α-FAPbI_(3) into itsδ-phase[2,10].Consequently,the best-performing α-FAPbI_(3)PSCs must be processed in an inert atmosphere with strictly controlled relative humidity(RH)and suffers from relatively poor reproducibility.Given the hard-to-control atmosphere at industrial scale,it is challenging yet imperative to eliminate the negative effects stemming from hygroscopic coordinating solvents[11−13].

Pinning energies of organic semiconductors in high-efficiency organic solar cells

With the emergence of new materials for high-efficiency organic solar cells(OSCs),understanding and finetuning the interface energetics become increasingly important.Precise determination of the so-called pinning energies,one of the critical characteristics of the material to predict the energy level alignment(ELA)at either electrode/organic or organic/organic interfaces,are urgently needed for the new materials.Here,pinning energies of a wide variety of newly developed donors and nonfullerene acceptors(NFAs)are measured through ultraviolet photoelectron spectroscopy.The positive pinning energies of the studied donors and the negative pinning energies of NFAs are in the same energy range of 4.3−4.6 eV,which follows the design rules developed for fullerene-based OSCs.The ELA for metal/organic and inorganic/organic interfaces follows the predicted behavior for all of the materials studied.For organic-organic heterojunctions where both the donor and the NFA feature strong intramolecular charge transfer,the pinning energies often underestimate the experimentally obtained interface vacuum level shift,which has consequences for OSC device performance.

Lead-free Ce-doped perovskite scintillators with high figure of merit

Lead halide perovskite scintillators have recently received extensive research attention owing to their short fluorescence lifetimes,low detection limits,and ease of fabrication compared to traditional scintillators.The nontoxic cerium-doped lead-free perovskites with intrinsically efficient and short lifetime d–f transitions are a prospective replacement for the toxic Pb^(2+).Here,we demonstrated Ce-doped cesium lanthanide chloride perovskites (Cs_(3)LnCl_(6),Ln=Gd,Y,Lu) synthesized through a facile solution method for the first time.These perovskites exhibit blue-violet emission,which arises from Ce 5d→4f transitions.Among three types of Cs_(3)LnCl_(6) perovskites,Ce:Cs_(3)LuCl_(6) exhibited high photoluminescence quantum yield (PLQY) of 82%and a short excited-state lifetime of approximately 34 ns.When utilized as X-ray scintillators,Ce:Cs_(3)LuCl_(6) crystals display a high light yield of 8120 photons per MeV and a low detection limit of 36.8 n Gy air s^(-1).Importantly,the figure of merit (FoM),representing the ratio of light yield to decay time,reaches 239,which is the highest reported value for lead-free perovskite scintillators up to now.Additionally,the fabrication of perovskite/PMMA films was undertaken for practical demonstrations in X-ray imaging,resulting in the attainment of a resolution of up to 8.38 lp/mm.We anticipate that this work will inspire the utilization of Ce-doped Cs_(3)LnCl_(6) perovskites in ultrafast scintillation applications such as high-energy physics,nuclear reaction monitoring,and dynamic X-ray imaging.

Boosting Peroxymonosulfate Activation via Co-Based LDH-Derived Magnetic Catalysts:A Dynamic and Static State Assessment of Efficient Radical-Assisted Electron Transfer Processes

Heterogeneous catalysts promoting efficient production of reactive species and dynamically stabilized electron transfer mechanisms for peroxomonosulfates(PMS)still lack systematic investigation.Herein,a more stable magnetic layered double oxides(CFLDO/N-C),was designed using self-polymerization and high temperature carbonization of dopamine.The CFLDO/N-C/PMS system effectively activated PMS to remove 99%(k=0.737 min^(-1))of tetracycline(TC)within 10 min.The CFLDO/N-C/PMS system exhibited favorable resistance to inorganic anions and natural organics,as well as satisfactory suitability for multiple pollutants.The magnetic properties of the catalyst facilitated the separation of catalysts from the liquid phase,resulting in excellent reproducibility and effectively reducing the leaching of metal ions.An electronic bridge was constructed between cobalt(the active platform of the catalyst)and PMS,inducing PMS to break the O-O bond to generate the active species.The combination of static analysis and dynamic evolution confirmed the effective adsorption of PMS on the catalyst surface as well as the strong radical-assisted electron transfer process.Eventually,we further identified the sites where the reactive species attacked the TC and evaluated the toxicity of the intermediates.These findings offer innovative insights into the rapid degradation of pollutants achieved by transition metals in SR-AOPs and its mechanistic elaboration.

A Novel Method of Fabricating Flexible Transparent Conductive Large Area Graphene Film

We fabricate flexible conductive and transparent graphene films on position-emission-tomography substrates and prepare large area graphene films by graphite oxide sheets with the new technical process. The multi-layer graphene oxide sheets can be chemically reduced by HNO3 and HI to form a highly conductive graphene film on a substrate at lower temperature. The reduced graphene oxide sheets show a high conductivity sheet with resistance of 476Ω/sq and transmittance of 76% at 550nm （6 layers）. The technique used to produce the transparent conductive graphene thin film is facile, inexpensive, and can be tunable for a large area production applied for electronics or touch screens.

Towards electrochemical hydrogen storage in liquid organic hydrogen carriers via proton-coupled electron transfers

Green hydrogen is identified as one of the prime clean energy carriers due to its high energy density and a zero emission of CO_(2).A possible solution for the transport of H_(2)in a safe and low-cost way is in the form of liquid organic hydrogen carriers(LOHCs).As an alternative to loading LOHC with H_(2)via a two-step procedure involving preliminary electrolytic production of H_(2)and subsequent chemical hydrogenation of the LOHC,we explore here the possibility of electrochemical hydrogen storage(EHS)via conversion of proton of a proton donor into a hydrogen atom involved in covalent bonds with the LOHC(R)via a protoncoupled electron transfer(PCET)reaction:2nH^(+)+2ne^(-)+Rox■n H_(2)^(0)Rred.We chose 9-fluorenone/fluorenol(Fnone/Fnol)conversion as such a model PCET reaction.The electrochemical activation of Fnone via two sequential electron transfers was monitored with in-situ and operando spectroscopies in absence and in presence of different alcohols as proton donors of different reactivity,which enabled us to both quantify and get the mechanistic insight on PCET.The possibility of hydrogen extraction from the loaded carrier molecule was illustrated by chemical activation.

Investigating the reason for high FF from ternary organic solar cells

Organic solar cells(OSCs)have attracted huge attention because of their unique merits[1−3].In last few years,thanks to the design of new materials and device engineering,the power conversion efficiencies(PCEs)of OSCs have surpassed 18%[4−8].The PM6:Y6 cells are efficient binary cells,offering high PCEs over 16%[9−11].The high performance originates from the efficient free charge generation and the ground state dipole field at the donor-acceptor interface that promotes the exciton dissociation[12].

Deformable Catalytic Material Derived from Mechanical Flexibility for Hydrogen Evolution Reaction

Deformable catalytic material with excellent flexible structure is a new type of catalyst that has been applied in various chemical reactions,especially electrocatalytic hydrogen evolution reaction(HER).In recent years,deformable catalysts for HER have made great progress and would become a research hotspot.The catalytic activities of deformable catalysts could be adjustable by the strain engineering and surface reconfiguration.The surface curvature of flexible catalytic materials is closely related to the electrocatalytic HER properties.Here,firstly,we systematically summarized self-adaptive catalytic performance of deformable catalysts and various micro–nanostructures evolution in catalytic HER process.Secondly,a series of strategies to design highly active catalysts based on the mechanical flexibility of lowdimensional nanomaterials were summarized.Last but not least,we presented the challenges and prospects of the study of flexible and deformable micro–nanostructures of electrocatalysts,which would further deepen the understanding of catalytic mechanisms of deformable HER catalyst.

Conducting Polymer-Based e-Refinery for Sustainable Hydrogen Peroxide Production

Electrocatalysis enables the industrial transition to sustainable production of chemicals using abundant precursors and electricity from renewable sources.De-centralized production of hydrogen peroxide(H_(2)O_(2))from water and oxygen of air is highly desirable for daily life and industry.We report an effective electrochemical refinery(e-refinery)for H_(2)O_(2)by means of electrocatalysis-controlled comproportionation reaction(2_(H)O+o→2HO),feeding pure water and oxygen only.Mesoporous nickel(Ⅱ)oxide(NiO)was used as electrocatalyst for oxygen evolution reaction(OER),producing oxygen at the anode.Conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)drove the oxygen reduction reaction(ORR),forming H_(2)O_(2)on the cathode.The reactions were evaluated in both half-cell and device configurations.The performance of the H_(2)O_(2)e-refinery,assembled on anion-exchange solid electrolyte and fed with pure water,was limited by the unbalanced ionic transport.Optimization of the operation conditions allowed a conversion efficiency of 80%.

Interpretable Machine Learning-Assisted High-Throughput Screening for Understanding NRR Electrocatalyst Performance Modulation between Active Center and C-N Coordination

Understanding the correlation between the fundamental descriptors and catalytic performance is meaningful to guide the design of high-performance electrochemical catalysts.However,exploring key factors that affect catalytic performance in the vast catalyst space remains challenging for people.Herein,to accurately identify the factors that affect the performance of N2 reduction,we apply interpretable machine learning(ML)to analyze high-throughput screening results,which is also suited to other surface reactions in catalysis.To expound on the paradigm,33 promising catalysts are screened from 168 carbon-supported candidates,specifically single-atom catalysts(SACs)supported by a BC_(3)monolayer(TM@V_(B/C)-N_(n)=_(0-3)-BC_(3))via high-throughput screening.Subsequently,the hybrid sampling method and XGBoost model are selected to classify eligible and non-eligible catalysts.Through feature interpretation using Shapley Additive Explanations(SHAP)analysis,two crucial features,that is,the number of valence electrons(N_(v))and nitrogen substitution(N_(n)),are screened out.Combining SHAP analysis and electronic structure calculations,the synergistic effect between an active center with low valence electron numbers and reasonable C-N coordination(a medium fraction of nitrogen substitution)can exhibit high catalytic performance.Finally,six superior catalysts with a limiting potential lower than-0.4 V are predicted.Our workflow offers a rational approach to obtaining key information on catalytic performance from high-throughput screening results to design efficient catalysts that can be applied to other materials and reactions.

Laser direct writing of flexible multifunctional airflow sensors on the Kevlar fabric

The growing interest in flexible devices has emerged as a global trend due to their advantages in flexibility,lightweight structure,and wearability,addressing the limitations of traditional devices.While wearable airflow sensors have been previously reported,the development of flexible fabric-based airflow sensors capable of functioning in environments with open flames—critical for fire rescue operations—has yet to be explored,largely due to the poor fire resistance of conventional fabrics.In this work,we first present a flexible,wearable,and multifunctional airflow sensor with excellent fire-resistant properties,fabricated through a simple direct laser writing process.This sensor maintains airflow detection capabilities even in the presence of open flames.Typically,the fabrication of fabric-based sensors involves complex procedures such as carbon materials doping or vapor-phase deposition,leading to lengthy preparation cycles and high costs.Furthermore,fabric-based devices are inherently prone to flammability.To address these challenges,we introduce twice-vertical laser-induced graphene(TVLIG)as a sensitive and reliable component for fire-resistant airflow sensors.The resulting TVLIG/Kevlar fabric can be integrated into various garments,particularly protective suits,to form sensitive and fire-resistant airflow sensors capable of detecting airflow velocity and direction in both two-dimensional(2D)and three-dimensional(3D)spaces during fire incidents.Additionally,the TVLIG patterns can be expanded to multifunctional platforms,such as glucose detection for injured individuals,offering further applications in rescue operations.This functional expansion reduces the burden on rescue personnel and streamlines device preparation.With its outstanding sensing capabilities,fire resistance,and expandability,the developed flexible airflow sensor shows great potential for various real-world rescue scenarios,promising advancements in wearable sensing technology for rescue engineering.

Effective adjustment of the optoelectronic properties of organic conjugated materials by synthesizing p-n diblock molecules

Because organic conjugated materials offer several advantages relative to their inorganic counterparts,the development of organic conjugated materials has been one of the most active research areas in optoelectronic materials.For almost two decades,the search for organic conjugated materials has represented a major driving force for research concerned with controlling the band gap of extended π-conjugated molecules.In particular,among the parameters affecting the performance of organic light-emitting diodes (OLEDs),the energy levels of organic conjugated materials play an important role because they can affect the driving voltage,wavelength,efficiency,and lifetime of the final device.Balanced injection and transport of electrons and holes are therefore crucial for achieving OLEDs with high quantum efficiency.In this regard,research into adjusting the energy levels of organic conjugated materials is very meaningful for the development of OLEDs.To adjust the energy levels of the organic conjugated materials,Huang et al.have presented a new molecular design and synthesis route that yields p-n diblock conjugated copolymers and oligomers.The present review summarizes and analyzes the progress on adjusting the optoelectronic properties of organic conjugated materials that is due to synthesizing p-n diblock molecules.We discusses primarily work done by Huang et al.,but also discusses work done elsewhere over the past few years.We also point out issues that require attention,and highlight hot spots that require further investigation.

Defect passivation by nontoxic biomaterial yields 21% efficiency perovskite solar cells

Defect passivation is one of the most important strategies to boost both the efficiency and stability of perovskite solar cells(PSCs).Here,nontoxic and sustainable forest-based biomaterial,betulin,is first introduced into perovskites.The experiments and calculations reveal that betulin can effectively passivate the uncoordinated lead ions in perovskites via sharing the lone pair electrons of hydroxyl group,promoting charge transport.As a result,the power conversion efficiencies of the p-i-n planar PSCs remarkably increase from 19.14%to 21.15%,with the improvement of other parameters.The hydrogen bonds of betulin lock methylamine and halogen ions along the grain boundaries and on the film surface and thus suppress ion migration,further stabilizing perovskite crystal structures.These positive effects enable the PSCs to maintain 90%of the initial efficiency after 30 days in ambient air with 60%±5%relative humidity,75%after 300 h aging at 85℃,and 55%after 250 h light soaking,respectively.This work opens a new pathway for using nontoxic and low-cost biomaterials from forest to make highly efficient and stable PSCs.

Nanocontacts give efficient hole injection in organic electronics

A key requirement for well performing devices based onorganic semiconductors is to ensure ohmic contacts, where anefficient hole and electron injection and extraction can beachieved at the electrode/semiconductor interfaces. The usualway to obtain ohmic contacts involves fine tuning of the energet-ics at the interfaces by using dopants (p- type and n-type) to con-trol the Fermi level of the semiconductor [1,2], or using suitablemetals or metal oxides as electrodes [3].

Ionic thermoelectric materials and devices

The tremendous amount of wasted heat from solar radiation and industry dissipation has motivated the development of thermoelectric concepts that directly convert heat into electricity.The main challenge in practical applications for thermoelectrics is the high cost from both materials and manufacturing.Recently,breakthrough progresses in ionic thermoelectrics open up new possibilities to charge energy storage devices when submitted to a temperature gradient.The charging voltage is internally from the ionic Seebeck effect of the electrolyte between two electrodes.Hence electrolytes with high thermoelectric figure of merit are classified as ionic thermoelectric materials.Most ionic thermoelectric materials are composed of abundant elements,and they can generate hundreds of times larger thermal voltage than that of electronic materials.This emerging thermoelectric category brings new hope to fabricate low cost and large area heat-to-energy conversion devices,and triggers a renewed interest for ionic thermodiffusion.In this review,we summarize the state of the art in the new field of ionic thermoelectrics,from the driving force of the ionic thermodiffusion to material and application developments.We present a general map of ionic thermoelectric materials,discuss the unique characters of each type of the reported electrolytes,and propose potential optimization and future topics of ionic thermoelectrics.

High yield manufacturing of fully screen-printed organic electrochemical transistors

The potential of the screen printing method for large-scale production of organic electrochemical transistors(OECTs),combining high production yield with low cost,is here demonstrated.Fully screen-printed OECTs of 1 mm^(2) area,based on poly(3,4-ethylenedioxythiophene)doped with poly(styrensulfonate)(PEDOT:PSS),have been manufactured on flexible polyethylene terephthalate(PET)substrates.The goal of this project effort has been to explore and develop the printing processing to enable high yield and stable transistor parameters,targeting miniaturized digital OECT circuits for large-scale integration(LSI).Of the 760 OECTs manufactured in one batch on a PET sheet,only two devices were found malfunctioning,thus achieving an overall manufacturing yield of 99.7%.A drain current ON/OFF ratio at least equal to 400 was applied as the strict exclusion principle for the yield,motivated by proper operation in LSI circuits.This consistent performance of low-footprint OECTs allows for the integration of PEDOT:PSS-based OECTs into complex logic circuits operating at high stability and accuracy.

A feasible and effective solution-processed PCBM electron extraction layer enabling the high VOC and efficient Cu_(2)ZnSn(S, Se)_(4) devices

Photo-generated carrier recombination loss at the CZTSSe/Cd S front interface is a key issue to the opencircuit voltage(V_(OC)) deficit of Cu_(2)ZnSnS_(x)Se_(4-x)(CZTSSe) solar cells. Here, by the aid of an easy-handling spin-coating method, a thin PCBM([6,6]-phenyl-C61-butyric acid methyl ester) layer as an electron extraction layer has been introduced on the top of CdS buffer layer to modify CZTSSe/CdS/ZnO-ITO(In_(2)O_(3):Sn) interfacial properties. Based on Sn^(4+)/DMSO(dimethyl sulfoxide) solution system, a totalarea efficiency of 12.87% with a VOC of 529 m V has been achieved. A comprehensive investigation on the influence of PCBM layer on carrier extraction, transportation and recombination processes has been carried out. It is found that the PCBM layer can smooth over the Cd S film roughness, thus beneficial for a dense and flat window layer. Furthermore, this CZTSSe/Cd S/PCBM heterostructure can accelerate carrier separation and extraction and block holes from the front interface as well, which is mainly ascribed to the downward band bending of the absorber and a widened space charge region. Our work provides a feasible way to improve the front interfacial property and the cell performance of CZTSSe solar cells by the aid of organic interfacial materials.

Two-dimensional molecular crystalline semiconductors towards advanced organic optoelectronics

The compelling demand for higher performance and lower cost in the optoelectronics industry has driven the development of organic semiconductors.Molecular crystalline semiconductors(MCSs),especially two-dimensional MCSs(2D-MCSs),possess intrinsic ordered structure,quantum confinement effect,high mobility,unique optical and electrical properties,and more ecological and cheaper production,which make great promises in high-performance optoelectronic applications.Here we provide a review of design principles and synthetic strategies for 2D-MCS materials,exploiting their potential as a revolution option in associated optoelectronic devices.The merits and limitations of each strategy are presented,and these molecular crystals are considered as a competitive choice for emerging semiconducting materials in information science.Finally,the current challenges and future perspectives in this field are also elaborated.

Author Correction: High yield manufacturing of fully screen-printed organic electrochemical transistors

Correction to:npj Flexible Electronics https://doi.org/10.1038/s41528-020-0078-9,published online 3 August 2020 The original version of the Supplementary Information associated with this Article contained an error in Supplementary Fig.3,in which the bottom part of the figure is not displayed.

Time-Dependent Density Matrix Renormalization Group Coupled with n-Mode Representation Potentials for the Excited State Radiationless Decay Rate:Formalism and Application to Azulene

We propose a method for calculating the nonradiative decay rates for polyatomic molecules including anharmonic effects of the potential energy surface(PES)in the Franck-Condon region.The method combines the n-mode repre-sentation method to construct the ab initio PES and the nearly exact time-dependent density matrix renormalization group method(TD-DMRG)to simulate quantum dynamics.In addition,in the framework of TD-DMRG,we further develop an algorithm to calculate the final-state-resolved rate coefficient which is very useful to analyze the contribution from each vibrational mode to the transition process.We use this method to study the internal conversion(IC)process of azulene after taking into account the anharmonicity of the ground state PES.The results show that even for this semi-rigid molecule,the intramode anharmonicity enhances the IC rate significantly,and after considering the two-mode coupling effect,the rate increases even further.The reason is that the anharmonicity enables the C-H vibrations to receive electronic energy while C-H vibrations do not contribute on the harmonic PES as the Huang-Rhys factor is close to 0.