Interfacial modification using the cross-linkable tannic acid for highly-efficient perovskite solar cells with excellent stability

Although the performance of perovskite solar cells(PSCs)has been dramatically increased in recent years,stability is still the main obstacle preventing the PSCs from being commercial.PSC device instability can be caused by a variety of reasons,including ions diffusion,surface and grain boundary defects,etc.In this work,the cross-linkable tannic acid(TA)is introduced to modify perovskite film through post-treatment method.The numerous organic functional groups(–OH and C=O)in TA can interact with the uncoordinated Pb^(2+)and I^(-)ions in perovskite,thus passivating defects and inhibiting ions diffusion.In addition,the formed TA network can absorb a small amount of the residual moisture inside the device to protect the perovskite layer.Furthermore,TA modification regulates the energy level of perovskite,and reduces interfacial charge recombination.Ultimately,following TA treatment,the device efficiency is increased significantly from 21.31%to 23.11%,with a decreased hysteresis effect.Notably,the treated device shows excellent air,thermal,and operational stability.In light of this,the readily available,inexpensive TA has the potential to operate as a multipurpose interfacial modifier to increase device efficiency while also enhancing device stability.

RBC Membrane Camouflaged Semiconducting Polymer Nanoparticles for Near-Infrared Photoacoustic Imaging and Photothermal Therapy

Semiconducting conjugated polymer nanoparticles(SPNs)represent an emerging class of phototheranostic materi-als with great promise for cancer treatment.In this report,low-bandgap electron donoracceptor(DA)-conjugated SPNs with sur-face cloaked by red blood cell membrane(RBCM)are developed for highly e ective photoacoustic imaging and photothermal therapy.The resulting RBCM-coated SPN(SPN@RBCM)displays remarkable near-infrared light absorption and good photosta-bility,as well as high photothermal conver-sion e ciency for photoacoustic imaging and photothermal therapy.Particularly,due to the small size(<5 nm),SPN@RBCM has the advantages of deep tumor penetration and rapid clearance from the body with no appreciable toxicity.The RBCM endows the SPNs with prolonged systematic circulation time,less reticuloendothelial system uptake and reduced immune-recognition,hence improving tumor accumulation after intravenous injection,which provides strong photoacoustic signals and exerts excellent photothermal therapeutic e ects.Thus,this work provides a valuable paradigm for safe and highly e cient tumor pho-toacoustic imaging and photothermal therapy for further clinical translation.

Thiazolo[5,4-d]thiazole-based covalent organic framework microspheres for blue light photocatalytic selective oxidation of amines with O2

Covalent organic frameworks(COFs)with photoactive units have attracted significant interest in visible light photocatalysis and can present a metal‐free scenario for activating O_(2).As a typical photoactive unit,thiazolo[5,4‐d]thiazole(TzTz)has rarely been added to COFs.However,circumventing the low reversibility of TzTz,it could be embedded into the building blocks beforehand,along with other bonds likeβ‐ketoenamine in forming COFs.TzTz was embedded into 1,1′‐biphenyl‐4,4′‐diamine(BD)using this approach to produce 4,4′‐(TzTz‐2,5‐diyl)dianiline(DTz).Under organobase‐modulated solvothermal conditions,combining 1,3,5‐triformylphloroglucinol(Tp)with BD and DTz resulted in the production ofβ‐ketoenamine‐linked TpBD‐COF and TpDTz‐COF.Both TpDTz‐COF and TpBD‐COF are microspheres.TpDTz‐COF possessed more adequate separation and charge migration than TpBD‐COF.This resulted in superior performance for the blue light photocatalytic selective oxidation of benzylamine with O_(2).Furthermore,with O_(2) as the main oxidant,a wealth of benzylamines could be converted into imines over TpDTz‐COF.Mechanistic investigations substantiate that oxidation of benzylamines obeys an electron transfer pathway,in which superoxide anion(O_(2)•–)is the crucial reactive oxygen species.This study highlights the superiority of TzTz‐embedded COFs in developing effective photocatalytic systems for organic transformations.

Merging benzotrithiophene covalent organic framework photocatalysis with TEMPO for selective oxidation of organic sulfides

Visible light photocatalysis of covalent organic frameworks(COFs) has made significant progress in recent years. Benzotrithiophene(BTT), a planar, electron-rich building block, turns out to be foundational in assembling COFs in which the fullπ-conjugation of BTT is essential to facilitate electron transfer. Herein, a sp~2 carbon-conjugated COF, namely BTT-sp~2c-COF, is assembled from benzo[1,2-b:3,4-b′:5,6-b′′]trithiophene-2,5,8-tricarbaldehyde and [1,1′:4′,1′′-terphenyl]-4,4′′-dicarbonitrile towards photocatalysis. More importantly, TEMPO(2,2,6,6-tetramethylpiperidin-1-yl)oxyl, 1 mol%) could considerably accelerate the selective oxidation of organic sulfides with O_(2) over BTT-sp~2c-COF. TEMPO mediates hole transfer between BTT-sp~2c-COF and organic sulfides, and O-atoms are incorporated into sulfoxides via an electron transfer pathway. Merging BTT-sp~2c-COF photocatalysis with TEMPO generally applies to transforming organic sulfides into sulfoxides. This work implies the full π-conjugation of electron-rich building blocks into COFs is a viable strategy for selective visible light photocatalysis.

Quick assembly of 1-alkylidenyl-tetrahydroisoquinolines via a Catellani reaction/NBS-mediated cyclization sequence and synthetic applications

We herein disclose a modular synthesis of 1-bromomethylene-THIQs involving a Catellani reaction of aryl iodides,aziridines,and terminal alkynes followed by an N-bromosuccinimide(NBS)-mediated cyclization.This approach features mild reaction conditions,wide substrate scope,good step-economy and good scalability.Based on this new method,we have accomplished the concise total synthesis of(±)-cularine,formal synthesis of 8-oxopseudopalmatine as well as the first total synthesis of dactyllactone A,demonstrating the wide synthetic potential of this method.

Divergent synthesis of chiral amines via Ni-catalyzed chemo-and enantioselective hydrogenation of alkynone imines

Ligand-mediated nickel-catalyzed asymmetric hydrogenation of alkynone imines has been achieved. By using Ni(OAc)_2·4H_2O/(S,S)-Ph-BPE complex as a catalyst, the chemo-and enantioselective hydrogenation of alkynone imines occurred efficiently to afford chiral propargyl amines with high yields and excellent enantioselectivities(up to 99% yield, >99% ee), leaving the readily reducible alkynyl group intact. Both the C=N and C≡C bonds of alkynone imines were hydrogenated efficiently in the presence of Ni(OAc)_2·4H_2O and Josiphos SL-J011-1, furnishing unfunctionalized chiral imines efficiently(up to 99% yield, >99% ee).The(Z)-allylamines and(E)-allylamines were also efficiently prepared from alkynone imines by the combination of the different catalytic systems. The preliminary mechanism study revealed that the reduction of alkynone imines was a stepwise process and the C=N bonds were preferably hydrogenated in the complete reduction of alkynone imines. The synthetic utility of this method was demonstrated by its application in the late-stage modification of the antiviral drug Zidovudine and the concise synthesis of chiral dibenzoazepine.

Tuning Energy Transfer in Metal-OrganicFrameworks for Fluorescence Turn-on Sensing of Hg(Ⅱ)Ions

Tuning F?rster resonance energy transfer(FRET)in metal-organic frameworks for fluorescence turn on sensing is rarely reported.Herein,we designed and synthesized several FRET-based metal-organic frameworks(MOFs)with different donor/acceptor ratios.Through the oxidation of the acceptor,the FRET process in MOFs can be efficiently modulated so as to turn-on the fluorescence of the framework in a controlled manner.Interestingly,the MOF with an optimized donor/acceptor ratio of 7.0 was used as an efficient fluorescence turn on sensor for Hg(Ⅱ)ions with good sensitivity and selectivity.We believe our present study will not only give a useful method to construct fluorescence turn-on sensors but also trigger the construction of novel FRET-based MOFs for the fluo-rescence turn-on sensing of target analytes in the future.

Sky Blue and Yellow Cluster Light-Emitting Diodes Based on Asymmetric Cu_(4)l_(4) Nanocubes

Controllably optimizing excited-state characteristics is crucial for luminescent nanoclusters but remains a formidable challenge.Herein,we report an effective"ligand-induced asymmetrization"strategy for constructing thermally activated delayed fluorescence-featured cubic Cu4l4 nanoclusters with asymmetric configurations,named[tBCzDBFDP]_(2)Cu_(4)l_(4) and[PTZDBFDP]_(2)Cu_(4)l_(4).Through changing 3,6-di-tert-butyl-carbazole(tBCz)to phenothiazine(PTZ)with a stronger electron-donating effect,emission color is tuned from greenish blue of[tBCzDBFDP]_(2)Cu_(4)l_(4) to yellow of[PTZDBFDP]_(2)Cu_(4)l_(4),as well as the triplet locally excited state of the former to the triplet charge transfer state of the latter.Temperature-correlated spectroscopic investigation indicates that in terms of triplet quenching suppression,[tBCzDBFDP]_(2)Cu_(4)l_(4) is superior to[PTZDBFDP]_(2)Cu_(4)l_(4),in accord with the stabilities of their triplet locally excited state and triplet charge transfer state.As a consequence,these asymmetric Cu4l4 nanocubes endowed their cluster light-emitting diodes with the external quantum efficiencies beyond 12%for sky blue and 8%for yellow.These results suggest the significance and effectiveness of ligand engineering for optoelectronic nanoclusters.

Solution-processed multi-resonance organic light-emitting diodes with high efficiency and narrowband emission

With excellent color purity(full-width half maximum(FWHM)<40 nm)and high quantum yield,multiresonance(MR)molecules can harvest both singlet and triplet excitons for highly efficient narrowband organic light-emitting diodes(OLEDs)owing to their thermally activated delayed fluorescence(TADF)nature.However,the highly rigid molecular skeleton with the oppositely positioned bo ron and nitrogen in generating MR effects results in the intrinsic difficulties in the solution-processing of MR-OLEDs.Here,we demonstrate a facile strategy to increase the solubility,enhance the efficiencies and modulate emission color of MR-TADF molecules by extending aromatic rings and introducing tert-butyls into the MR backbone.Two MR-TADF emitters with smaller singlet-triplet splitting energies(ΔE~(ST))and larger oscillator strengths were prepared conveniently,and the solution-processed MR-OLEDs were fabricated for the first time,exhibiting efficient bluish-green electroluminescence with narrow FWHM of 32 nm and external quantum efficiency of 16.3%,which are even comparable to the state-of-the-art performances of the vacuum-evaporated devices.These results prove the feasibility of designing efficient solutionprocessible MR molecules,offering important clues in developing high-performance solution-processed MR-OLEDs with high efficiency and color purity.

Writing and Erasing Encryption Information Based on Frustrated Lewis Pair Chemistry

Lewis acid−base adducts resulting from instantaneous interactions provide a cost-effective strategy for color tuning and anticounterfeiting information.Herein,we report the construction of luminescent Lewis acid−base adducts via inkjet printing.Due to the unique weak coordination bond of B→N,it is feasible to construct anticounterfeiting information that is easy to erase.The in situ postsynthesis of the luminescent quick response codes via inkjet printing facilitates precision chemistry control to change the emission ranging from deep-blue(peaking at 407 nm)to orange-red(peaking at 597 nm).The encrypted information can be quickly erased either by modulating the temperature to dissociate the weak coordination or strong Lewis base to promote a neutralization reaction.

Asymmetric Two-Component Alkenyl Catellani Reaction for the Construction of C—N Axial Chirality

Herein,we report an asymmetric two-component alkenyl Catellani reaction for the construction of C—N axial chirality through a palladium/chiral norbornene cooperative catalysis and an axial-to-axial chirality transfer process.Various partially aromatic iodinated 2-pyridones,quinolones,coumarin and uracil substrates react with 2,6-disubstituted aryl bromides with a tethered amide group,to afford a wide variety of polycyclic C—N atropisomers(38 examples,up to 97%e.e.).The obtained C—N axial chirality originates from the preformed transient C—C axial chirality with high fidelity.The synthetic utility of this chemistry is demonstrated by facile prepa-ration of complex quinoline and pyridine based C—N atropisomers through a N-deprotection and aromatization sequence.In addi-tion,a remote axial-to-central diastereoinduction process dictated by C—N axial chirality is observed with excellent diastereocontrol.

Altering alkyl-chains branching positions for boosting the performance of small-molecule acceptors for highly efficient nonfullerene organic solar cells

The emergence of the latest generation of small-molecule acceptor(SMA)materials,with Y6 as a typical example,accounts for the surge in device performance for organic solar cells(OSCs).This study proposes two new acceptors named Y6-C2 and Y6-C3,from judicious alteration of alkyl-chains branching positions away from the Y6 backbone.Compared to the Y6,the Y6-C2 exhibits similar optical and electrochemical properties,but better molecular packing and enhanced crystallinity.In contrast,the Y6-C3 shows a significant blue-shift absorption in the solid state relative to the Y6 and Y6-C2.The as-cast PM6:Y6-C2-based OSC yields a higher power conversion efficiency(PCE)of 15.89%than those based on the Y6(15.24%)and Y6-C3(13.76%),representing the highest known value for as-cast nonfullerene OSCs.Prominently,the Y6-C2 displays a good compatibility with the PC71BM.Therefore,a ternary OSC device based on PM6:Y6-C2:PC71BM(1.0:1.0:0.2)was produced,and it exhibits an outstanding PCE of 17.06%and an impressive fill factor(FF)of 0.772.Our results improve understanding of the structureproperty relationship for state-of-the-art SMAs and demonstrate that modulating the structure of SMAs via fine-tuning of alkylchains branching positions is an effective method to enhance their performance.

High-efficiency all-small-molecule organic solar cells based on an organic molecule donor with an asymmetric thieno[2,3-f]benzofuran unit

Two p-type small molecules BDTT-TR and TBFT-TR with benzo[1,2-b′:4,5-b′]dithiophene(BDT)and thieno[2,3-f]benzofuran(TBF)as central core units are synthesized and used as donors in all-small-molecule organic solar cells(all-SMOSCs)with a narrow-bandgap small molecule Y6(2,2′-((2 Z,2′Z)-((12,13-bis(2-ethylhexyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2″,3’′:4’,5′]thieno[2′,3′:4,5]pyrrolo[3,2-g]thieno[2′,3′:4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1 H-indene-2,1-diylidene))dimalononitrile)as the acceptor.In comparison to BDTT-TR with centrosymmetric BDT as the central unit,TBFT-TR with asymmetric TBF as the central unit shows red-shifted absorption,higher charge-carrier mobility and better charge pathway in blend films.The power conversion efficiency(PCE)of the all-SMOSCs based on TBFT-TR:Y6 reaches 14.03%with a higher short-circuit current density of 24.59 m A cm-2 and a higher fill factor of72.78%compared to the BDTT-TR:Y6 system.The PCE of 14.03%is among the top efficiencies of all-SMOSCs reported in the literature to date.

Simple sulfone-bridged heterohelicene structure realizes ultraviolet narrowband thermally activated delayed fluorescence,circularly polarized luminescence,and room temperature phosphorescence

Due to narrowband emission and high quantum efficiencies,polycyclic aromatic heterocycles with multi-resonance thermally activated delayed fluorescence(MR-TADF)properties have recently gained considerable attention in the organic optoelectronic field.Albeit their great promise in the full visible region covering from blue to red,MR-TADF emitters with ultraviolet emission have been rarely reported.Through locking the two ortho-positions of a triphenylamine core by sulfone groups,a simple polycyclic aromatic heterocycle,BTPT,was facilely constructed,exhibiting 368 nm ultraviolet emission with a narrow full width at half maximum(FWHM)of 33 nm.Its neat film exhibited distinct TADF property with a main emission peak at 388 nm.Noteworthily,the enantiomeric crystals of BTPT not only demonstrated significant circularly polarized luminescence(CPL)with large luminescence dissymmetry factor in the 10^(-3) order but also displayed obvious room temperature phosphorescence(RTP).The relationship between this innovative helical unit and unique photophysical properties,including ultraviolet MR-TADF,CPL,and RTP,was reasonably revealed.

Monoradically luminescent polymers by a super acid-catalyzed polymerization and deep-red electroluminescence

Luminescent radicals have received great attention recently due to their idiographic luminescent properties and potential 100%utilization efficiency of doublets under electrical excitation.However,luminescent radical polymers are rarely explored owing to their challenging molecular design and synthesis.Herein,we report an efficient approach to construct luminescent radical polymers by a super acid-catalyzed polymerization reaction proceeded at room temperature,which intrinsically avoid the heavy metal catalyst.The obtained polymers exhibit the unique paramagnetic signals,good thermal properties,and excellent photostability.Moreover,the quantifiable electroluminescence of such radical polymers was demonstrated for the first time.

Confining electron donor and acceptor in space to realize high efficiency charge-transfer luminescence

Through-bond charge transfer (CT) could easily occur between an electron donor (D) and an electron acceptor (A),which is fundamental to design various D-A type emissive materials for organic light-emitting diode (OLED) application. Although D-A type emitters have been developed for many years, what makes them in the spotlight is the rise of thermally activated delayed fluorescence (TADF) materials.In 2012, Adachi et al.[1] reported a series of D-A emitters with TADF features to fully utilize electrogenerated excitons. After the pioneer work, numerous TADF materials with D-A structure were extensively explored for the application of organic light emitting diodes (OLEDs)[2].

Simple Double Hetero[5]helicenes Realize Highly Efficient and Narrowband Circularly Polarized Organic Light-Emitting Diodes

Helicene-based emitters with unique inherent circularly polarized luminescence(CPL)are promising yet remain a formidable challenge for highly efficient circularly polarized organic light-emitting diodes(CP-OLEDs),ascribed to their tough synthesis,low emission efficiency,and easy racemization in the thermal deposition process.Herein,a pair of helicenebased enantiomers,namely(P)-helicene-BN and(M)-helicene-BN,were developed,which merge helical chirality and the B/N/S inserted polycyclic aromatic framework to concurrently feature CPL and narrow thermally activated delayed fluorescence(TADF)characteristics.Benefiting from the excellent thermal/photophysical/chiroptical properties,the narrowband green CP-OLEDs based on enantiomers achieved maximum external quantum efficiencies(EQE_(max))of up to 31.5%,and dissymmetry factor(|g_(EL)|)of 2.2×10^(−3).This work reveals the great potential of helicene-based emitters in CP-OLEDs.

π-Stacked host materials based on spirofluorene scaffolds for warm white OLEDs achieving 94.7 lm W^(-1) at 1,000 cd m^(-2)

Power efficiency(PE)at high brightness is considered as the rigorous standard of high-quality white organic light-emitting diodes(WOLEDs),for which the host material plays a significant role in energy conservation for practical lighting applications.Herein,PE is successfully enhanced to a new level through the method ofπ-stacked host molecular with spirofluorene scaffold.We design host materials by confining two donor units in a very short distance to enlarge theπ-electron spatial delocalization for facilitating the hole hopping process and engaging a rigid donor as the space-lock to suppress the quenching effect as well as induce host bipolar property.Based on this unique molecular design,the red,green,and blue(RGB)monochromic organic lightemitting diodes(OLEDs)demonstrate high external quantum efficiencies(EQEs)of 28.4%,26.0%,and 31.2%with ultralow roll-off,respectively.More encouragingly,the warm WOLEDs achieve record-high current efficiency(CE)of 109.5 cd A^(-1),PE of 109.1 lm W^(-1),and EQE of 32.9%.Even under operating brightness of 1,000 cd m^(-2),the devices can still realize 94.7 lm W^(-1)of PE,which represents the highest applicable PE value in the reported WOLEDs and for the first time single-host based WOLEDs with a performance exceeding that of a conventional fluorescent tube(70 lm W^(-1))without any light-extraction technique.

Resonance hosts for high efficiency solution-processed blue and white electrophosphorescent devices

The exploration of high-performance solution-processible host materials for blue and white electrophosphorescent devices is a key and fundamental challenge in the ongoing development of organic semiconductors.Herein,two solution-processible resonance host materials with self-adaptive characteristics are delicately designed and constructed.Because of the dynamic tautomerization upon resonance variation,these smart hosts show self-adaptive and selectively enhanced charge carrier flux at high triplet energy levels.Conferred by the resonance molecules,solution-processed blue and white devices exhibit excellent maximum current efficiencies(CEs)of 29.8 and 57.3 cd A−1,and external quantum efficiencies(EQEs)up to 14.5%and 23.5%,respectively.Our works highlight the significant progress of the solution-processed phosphorescent organic light-emitting diodes(PhOLEDs)using resonance host molecules,potentially furnishing a leap forward in constructing advanced organic semiconductors for next-generation optoelectronic devices.

Constructing Donor-Resonance-Donor Molecules for AcceptorFree Bipolar Organic Semiconductors

Organic semiconductors with bipolar transporting character are highly attractive as they offer the possibility to achieve high optoelectronic performance in simple device structures.However,the continual efforts in preparing bipolar materials are focusing on donor-acceptor(D-A)architectures by introducing both electron-donating and electron-withdrawing units into one molecule in static molecular design principles.Here,we report a dynamic approach to construct bipolar materials using only electron-donating carbazoles connected by N-P=X resonance linkages in a donor-resonance-donor(D-r-D)structure.By facilitating the stimuli-responsive resonance variation,these D-r-D molecules exhibit extraordinary bipolar properties by positively charging one donor of carbazole in enantiotropic N^(+)=P-X-canonical forms for electron transport without the involvement of any acceptors.With thus realized efficient and balanced charge transport,blue and deep-blue phosphorescent organic light emitting diodes hosted by these D-r-D molecules show high external quantum efficiencies up to 16.2%and 18.3%in vacuum-deposited and spin-coated devices,respectively.These results via the D-r-D molecular design strategy represent an important concept advance in constructing bipolar organic optoelectronic semiconductors dynamically for high-performance device applications.