Fluorene pendant-functionalization of poly(N-vinylcarbazole)as deep-blue fluorescent and host materials for polymer light-emitting diodes

π-Electron coupling of pendant conjugated segment inπ-stacked semiconducting polymers always causes the formation of defect trapped sites and further quenched high-band excitons,which is harmful to the performance and stability of deep-blue polymer light-emitting diodes(PLEDs).Herein,considerate of“defect”carbazole(Cz)electromers in poly(N-vinylcarbazole)(PVK),a series of fluorene units are introduced into pendant segments(PVCz-DMeF,PVCz-FMeNPh and PVCz-DFMeNPh)to suppress the strongπ-electron coupling of pendant Cz units and enhance radiative transition toward fabricating sable PLEDs.Compared to PVCz-FMeNPh and PVCz-DFMeNPh,PVCz-DMeF spin-coated films show a relatively efficient deep-blue emission,completely similar to its single pendant chromophore,confirmed an extremely weak charge-transfer and electron coupling between adjacent pendant segments.Therefore,PLEDs based on PVCz-DMeF present stable and deep-blue emission with a high color purity(0.17,0.08),associated with extremely weak defect emission at 600∼700nm(induced by carbazole electromers).Finally,PLEDs based on PVCz-DMeF/F8BT blended films(1:1)also present the high maximum luminance(Lmax)of 6261 cd/m2 and current efficiency(CE_(max))of 2.03 cd/A,confirmed slightly trapped sites formation.Therefore,precisely control the arrangement and packing model of pendant units inπ-stacked polymer is an essential prerequisite for building efficient and stable emitter for optoelectronic devices.

In Situ Super-Hindrance-Triggered Multilayer Cracks for Random Lasing inπ-Functional Nanopolymer Films

In situ self-assembly of semiconducting emitters into multilayer cracks is a significant solution-processing method to fabricate organic high-Q lasers.However,it is still difficult to realize from conventional conjugated polymers.Herein,we create the molecular super-hindrance-etching technology,based on theπ-functional nanopolymer PG-Cz,to modulate multilayer cracks applied in organic single-component random lasers.Massive interface cracks are formed by promoting interchain disentanglement with the super-steric hindrance effect ofπ-interrupted main chains,and multilayer morphologies with photonic-crystal-like ordering are also generated simultaneously during the drop-casting method.Meanwhile,the enhancement of quantum yields on micrometer-thick films(Φ=40%to 50%)ensures high-efficient and ultrastable deep-blue emission.Furthermore,a deep-blue random lasing is achieved with narrow linewidths~0.08 nm and high-quality factors Q≈5,500 to 6,200.These findings will offer promising pathways of organicπ-nanopolymers for the simplification of solution processes applied in lasing devices and wearable photonics.

Nanogridarene:A Rising Nanomolecular Integration Platform of Organic Intelligence

In the background of organic electronics,nanogridarenes with the criteria of well-defined edge and extendable vertexes were discovered toward chemical intellibots in 2014.Herein,Friedel-Crafts Gridization(FCG)as the molecular installing technology(MIT)will be highlighted to synthesize various monogrids,multigrids and polygrids that would be potential cornerstone of covalent window,molecular integration and circuit as well as organic robots.

An Overview of Molecular Packing Mode in Two-Dimensional Organic Nanomaterials via Supramolecular Assembly

Two-dimensional(2D)organic nanomaterials are attracting increasing research interest and expected to be the ideal candidate for futureproofed flexible electronics and biotechnologies.Owing to the complex molecular structures and multiple intermolecular interactions in organic systems,deeper understanding of rational molecular design and assembly principles is urgently required.In this review,a collection of molecular packing mode in the 2D organic nanomaterials via supramolecular assembly is presented,so as to help explicit the relationship among molecular structures,supramolecular interactions and molecular packing motifs in 2D assembly systems.We also provide a rational and accessible schematic model to demonstrate several typical kinds of molecular packing motifs for the prediction of the 2D morphology.

Cross-Scale Synthesis of Organic High-k Semiconductors Based on Spiro-Gridized Nanopolymers

High dielectric constants in organic semiconductors have been identified as a central challenge for the improvement in not only piexoelectric,preolecric,and freeltric efcts but also photoclecric conversion eficiency in OPVs,carrier mobility in OFETS,and charge density in charge-trapping memories.Herein,we report an ultralong persistence length(≈41 nm)efet of spiro-fused organic nanopolymers on dielectric properties,together with excitonic and charge carrier behaviors.The state-of-the-art nanopolymers,namely,nanopolyspirogrids(NPSGs),are synthesized via the simple crossscale Friedel-Crafts polygridlization of AjB-type nanomonomers.The high dielectric constant(k=8.43)of NPSG is firstly achieved by locking spiro-polygridization efect that results in the enhancement of dipole polarization.When doping into a polystyrene-based dielectric layer,such a high-k feature of NPSG increases the feld-ffct carrier mobility from 0.20 to 0.90cm^(2)Vl s'in pentacene OFET devices.Meanwhile,amorphous NPSG film exhibits an ultralow energy disorder(<50 meV)for an exellent zero-field hole mobility of 3.94×10^(-1)cm^(2)V^(-1)s^(-1).surpassing most of the amorphousπconjugated polymers Onganic nanopolymers with high dielectric constants open a new way to break through the bottleneck of eficiency and multifunctionality in the blueprint of the fourth generation semiconductors.

Theoretical Studies on Novel Gridspiroarenes: Structures, Noncovalent Interactions and Reorganization Energies

Organic semiconductor materials with low reorganization energy have various applications such as in organic light-emitting diodes (OLEDs),organic field-effect transistor (OFETs) and organic solar cells (OSCs).In this work,we have designed a new class of gridspiroarenes (GS-SFX and GS-SITF) with #-shaped structures,which have novel crisscross geometrical structures compared to widely used spirocyclic arenes-SFX and SITF.The structure electronic properties,adiabatic ionization potentials (IPa),adiabatic electron affinities (EAa) and reorganization energies (λ) of GS-SFX and GS-SITF have been calculated using density functional theory (DFT) method.The calculated HOMO and LUMO spatial distributions suggest that GS-SFX and GS-SITF have better transport properties.The noncovalent interaction analysis shows the weak intramolecular interactions between their arms.The results indicate that the reorganization energies of GS-SFX and GS-SITF are significantly reduced compared to the dimer structures-DSFX and DSITF.Furthermore,the GS-SITF1 which is one of the isomers of GS-SITF exhibits the lowest values for λ(h)(0.067 eV) and λ(e)(0.153 eV).Therefore,we believe the predicted structure,electronic property,and reorganization energy are good indicator for transport materials.This work has systematically studied the effect of gridization,which provides insights to design organic semiconductor materials with excellent charge transport properties.

One-Pot Synthesis of Spiro[fluorene-9,9'-xanthene]Derivatives

As a novel class of spirofluorenes,spirobifluorene(SBF)and spiro[fluo-rene-9,9'-xanthene]derivatives(SFXs)have orthogonal geometric config-uration,spiro-conjugation effect,and rigid steric hindrance,which can be widely used in the fields of synthetic chemistry,materials chemistry and supramolecular chemistry.Due to their facile one-pot synthetic route,and to the variety of molecular designs,SFXs are expected to become new spiro functional materials that replace SBF.In this review,we present the history,development and expansion of SFXs synthesis in one-pot methods,and the advantages and limitations of one-pot synthesis are also dis-cussed.

Self-assembly into Polymorphic 2D Nanosheets with Crystallization-Induced Emission Enhancement

Organic micro/nanocrystals with polymorphic tailorability and perfect platform to modulate decode the complex relationship among molecular structures,supramolecular/noncovalent interactions,aggregates and exciton behaviors.Herein,we precisely tune the polymorphic two-dimensional organic nanosheets(2DONs)of cyano-spirocyclic aromatic hydrocarbon(2'-CN-SFX),where the crystal growth processes are dominated by precursor concentration.The low concentration(ca.2 mmol/L)affords the rhombus-like nanosheets with monoclinic P21/c space group,in which molecules adopt antiparallel and slipped stacking mode.In contrast,the high concentration(ca.4 mmol/L)favors herringbone-like molecular packing pattern and then generates shuttle-like nanosheets with monoclinic C2/c space group.Both above polymorphic nanosheets exhibit unprecedented crystallization-induced emission en-hancement(CIEE)feature that increases the photoluminescence quantum yields(PLQYs)from 16%in solution,21%in amorphous film to 37%-39%in crystalline states.This result will offer promising opportunities for nanophotonics and organic intelligent semi-conductors.