Enhancing Optoelectronic Anisotropy in Highly Oriented Thin Films by Fluorine Substitution in Novel Semiconducting Polymers.

The recent past has witnessed remarkable progress in organic electronics, driven by the quest for flexible, lightweight, and cost-effective electronic devices. Semiconducting polymers (SCPs) have emerged as key materials in this field, offering unique electronic and optoelectronic properties along with mechanical flexibility. This study focuses on designing, synthesizing, and utilizing novel donor-acceptor (D-A) copolymer-based SCPs introducing a difluorothiophene moiety in the polymeric backbone.

Nanometer-scaled landscape of polymer: fullerene blends mapped with visible-SNOM.

Bulk heterojunction is one key concept leading to breakthrough in organic photovoltaics. The active layer is expectantly formed of distinct morphologies that carry out their respective roles in photovoltaic performance. The morphology-performance relationship however remains stymied, because unequivocal morphology at the nanoscale is not available.

Deep Blue Fluorescent Material with an Extremely High Ratio of Horizontal Orientation to Enhance Light Outcoupling Efficiency (44%) and External Quantum Efficiency in Doped and Non-Doped Organic Light-Emitting Diodes.

A novel bis-4Ph-substituted 9,10-dipehnylanthracene deep blue [1931 CIE (0.15, 0.08)] fluorescent compound, , has been synthesized and characterized for organic light-emitting diode (OLED) applications.

Design of Thienothiophene-Based Copolymers with Various Side Chain-End Groups for Efficient Polymer Solar Cells.

Three two-dimensional donor-acceptor conjugated copolymers consisting of a benzo[1,2-b:4,5-']dithiophene derivative and thieno[3,2-]thiophene with a conjugated side chain were designed and synthesized for use in bulk heterojunction (BHJ) or nonfullerene polymer solar cells (PSCs). Through attaching various acceptor end groups to the conjugated side chain on the thieno[3,2-]thiophene moiety, the electronic, photophysical, and morphological properties of these copolymers were significantly affected. It was found that the intermolecular charge transfer interactions were enhanced with the increase in the acceptor strength on the thieno[3,2-]thiophene moiety.

Rapid template-free synthesis of nanostructured conducting polymer films by tuning their morphology using hyperbranched polymer additives.

Nanostructures in conducting polymer films can enhance charge carrier and ion transfer, provide porosity with high specific area and confer unique optoelectronic properties for potential applications. A general and facile synthesis has been developed to prepare nanostructured conducting polymer films without the need for using templates. This simple approach employs hyperbranched polymers as additives to tune the morphology of conducting polymer films into a continuous nanofibril network.

Simple Molecular-Engineering Approach for Enhancing Orientation and Outcoupling Efficiency of Thermally Activated Delayed Fluorescent Emitters without Red-Shifting Emission.

The inclusion of a tetraphenylbenzene (4Ph) unit in thermally activated delayed fluorescence emitters is demonstrated as a novel strategy for greatly enhancing the horizontally oriented alignment of the emitters without shifting the emission spectrum to longer wavelengths. Doping of blue-emitting 4PhOXDDMAC or greenish-blue-emitting 4PhOXDPXZ into o-DiCbzBz host layers yielded much higher degrees of horizontally oriented alignment for the emitter (up to 92%) compared to those when the 4Ph unit was excluded (69 and 75%, respectively). The enhanced alignment results in high outcoupling efficiencies of 24 and 35% in organic light-emitting diodes based on 4PhOXDDMAC and 4PhOXDPXZ, respectively, and boosts the external quantum efficiencies to values (8.

A star-shaped conjugated molecule featuring a triazole core and diketopyrrolopyrrole branches is an efficient electron-selective interlayer for inverted polymer solar cells.

A novel triazole-cored, star-shaped, conjugated molecule (TDGTPA) has been synthesized for use as an electron-selective interlayer in inverted polymer solar cells (PSCs). This star-shaped molecule comprised a triazole unit as the central core, 2,5-thienyl diketopyrrolopyrrole units as π-conjugated bridges, and -butyl-substituted triphenylamine units as both end groups and donor units. The inverted PSC had the device structure indium tin oxide/ZnO/TDGTPA/poly(3-hexylthiophene) (P3HT)/fullerene derivative (PCBM)/MoO/Ag.

Functional graded fullerene derivatives for improving the fill factor and device stability of inverted-type perovskite solar cells.

A graded fullerene derivative thin film was used as a dual-functional electron transport layer (ETL) in CHNHPbI (MAPbI) solar cells, to improve the fill factor (FF) and device stability. The graded ETL was made by mixing phenyl-C-butyric acid methyl ester (PCBM) molecules and C-diphenylmethanofullerene-oligoether (C-DPM-OE) molecules using the spin-coating method. The formation of the graded ETLs can be due to the phase separation between hydrophobic PCBM and hydrophilic C-DPM-OE, which was confirmed by XPS depth-profile analysis and an electron energy-loss spectroscope.

Isoindigo-dicyanobithiophene-Based Copolymer for High Performance Polymer-Fullerene Solar Cells Reaching 1.06 V Open Circuit Voltage and 8.36% Power Conversion Efficiency.

To investigate the effect of substitution of cyano groups (CN) on D-π-A type conjugated copolymer in photophysical and photovoltaic properties, a non-CN-substituted and a CN-substituted isoindigo-based copolymers were synthesized and characterized. Having dicyano-substituted bithiophene as electron-donating segment and isoindigo as electron-accepting segment, exhibits a deeper highest occupied molecular orbital energy level (HOMO) than that of the non-CN-substituted . Benefiting from the improved solubility via copolymer side-chain substituent (2-decylteradecyl), inverted solar cells fabricated with a thick (∼200 nm) active layer (:PCBM, 1:2.

Oxasmaragdyrins as New and Efficient Hole-Transporting Materials for High-Performance Perovskite Solar Cells.

The high performance of the perovskite solar cells (PSCs) cannot be achieved without a layer of efficient hole-transporting materials (HTMs) to retard the charge recombination and transport the photogenerated hole to the counterelectrode. Herein, we report the use of boryl oxasmaragdyrins (SM01, SM09, and SM13), a family of aromatic core-modified expanded porphyrins, as efficient hole-transporting materials (HTMs) for perovskite solar cells (PSCs). These oxasmaragdyrins demonstrated complementary absorption spectra in the low-energy region, good redox reversibility, good thermal stability, suitable energy levels with CHNHPbI perovskite, and high hole mobility.

Structure-Property Relationship Study of Donor and Acceptor 2,6-Disubstituted BODIPY Derivatives for High Performance Dye-Sensitized Solar Cells.

Seven donor and acceptor 2,6-disubstituted 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) dyes have been synthesized and characterized. Including MPBTCA, which is a known compound, the seven BODIPY dyes have been characterized by varied physical methods, such as UV/Visible absorption spectroscopy, low energy photo-electron spectroscopy (AC-2), and HOMO-LUMO DFT/TDDFT calculation. All seven BODIPY dyes have absorption λ around 535-545 nm, which is significantly longer than 499 nm of 4,4-difluoro-1,3,5,7,8-pentamethyl-4-bora-3a,4a-diaza-s-indacene (PM 546).

SimCP3-An Advanced Homologue of SimCP2 as a Solution-Processed Small Molecular Host Material for Blue Phosphorescence Organic Light-Emitting Diodes.

We have overcome the synthetic difficulty of 9,9',9'',9''',9'''',9'''''-((phenylsilanetriyl)tris(benzene-5,3,1-triyl))hexakis(9H-carbazole) () an advanced homologue of previously known as a solution-processed, high triplet gap energy host material for a blue phosphorescence dopant. A series of organic light-emitting diodes based on blue phosphorescence dopant iridium (III) bis(4,6-difluorophenylpyridinato)picolate, FIrpic, were fabricated and tested to demonstrate the validity of solution-processed in the device fabrication.

Nano-structured CuO-Cu2O Complex Thin Film for Application in CH3NH3PbI3 Perovskite Solar Cells.

Nano-structured CuO-Cu2O complex thin film-based perovskite solar cells were fabricated on an indium tin oxide (ITO)-coated glass and studied. Copper (Cu) thin films with a purity of 99.995 % were deposited on an ITO-coated glass by magnetron reactive sputtering.

Synthesis and characterization of heteroatom-bridged bis-spirobifluorenes for the application of organic light-emitting diodes.

Pure 2-iodo-9,9'-spirobifluorene was synthesized by an efficient method without troublesome iodination of 9,9-spirobifluorene (SP) or the Sandmeyer reaction of 2-amino-9,9'-spirobifluorene. A series of main group element-bridged bis-9,9'-spirobifluorene derivatives were synthesized via coupling reactions of 2-iodo-9,9'-spirobifluorene and main group element-containing precursors. These heteroatom-bridged bis-spirobifluorenes show large triplet state energy gaps, high glass transition temperatures, and varied charge-transporting properties advantageous to the host materials for blue phosphorescence organic light-emitting diodes.

High-efficiency small-molecule-based organic light emitting devices with solution processes and oxadiazole-based electron transport materials.

We demonstrate high-efficiency small-molecule-based white phosphorescent organic light emitting diodes (PHOLEDs) by single-active-layer solution-based processes with the current efficiency of 17.3 cdA(-1) and maximum luminous efficiency of 8.86 lmW(-1) at a current density of 1 mA cm(-2).

Improve efficiency of white organic light-emitting diodes by using nanosphere arrays in color conversion layers.

The authors demonstrated an efficient color conversion layer (CCL) by using nanosphere arrays in down-converted white organic light-emitting diodes (WOLEDs). The introduced periodical nanospheres not only helped extract the confined light in devices, but also increased the effective light path to achieve high-efficiency color conversion. By applying a CCL with red phosphor on a 400-nm-period nanosphere array, we achieved 137% color conversion ratio for blue OLEDs, which was 2.

Rare solvent annealing effective benzo(1,2-b:4,5-b')dithiophene-based low band-gap polymer for bulk heterojunction organic photovoltaics.

A newly synthesized benzo(1,2-b:4,5-b')dithiophene-based low band-gap copolymer pBCN is amenable to solvent annealing in the fabrication of organic photovoltaics, of which power conversion efficiency is greatly improved to 4.2% with PC(61)BM or 4.9% with PC(71)BM.

Hydroxynaphthyridine-derived group III metal chelates: wide band gap and deep blue analogues of green Alq3 (tris(8-hydroxyquinolate)aluminum) and their versatile applications for organic light-emitting diodes.

A series of group III metal chelates have been synthesized and characterized for the versatile application of organic light-emitting diodes (OLEDs). These metal chelates are based on 4-hydroxy-1,5-naphthyridine derivates as chelating ligands, and they are the blue version analogues of well-known green fluorophore Alq(3) (tris(8-hydroxyquinolinato)aluminum). These chelating ligands and their metal chelates were easily prepared with an improved synthetic method, and they were facially purified by a sublimation process, which enables the materials to be readily available in bulk quantity and facilitates their usage in OLEDs.

Solid-state highly fluorescent diphenylaminospirobifluorenylfumaronitrile red emitters for non-doped organic light-emitting diodes.

Bright (maximum 11,000 cd m(-2) and 500 cd m(-2) at 20 mA cm(-2)) and efficient (maximum external quantum efficiency of 3.1% at 1 mA cm(-2)) red (CIE, x = 0.66, y = 0.

Iridium(I) pyridyl azolate complexes with saturated red metal-to-ligand charge transfer phosphorescence; fundamental and potential applications in organic light-emitting diodes.

Preparation of a new series of neutral metal complexes [(cod)Ir(fppz)] (1), [(cod)Ir(bppz)] (2), [(cod)Ir(fptz)] (3) and [(cod)Ir(bptz)] (4), bearing one cod ligand and a pyridyl azolate chelate are reported. A single-crystal X-ray diffraction study of 3 reveals the expected distorted square-planar geometry. The lowest absorption band consists of IrI atom increased triplet dpi-->pi* transitions (3MLCT), the assignment of which is firmly supported by the theoretical approaches.

Novel carbazole/fluorene hybrids: host materials for blue phosphorescent OLEDs.

[reaction: see text] A series of carbazole/fluorene (CBZm-Fn) hybrids were effectively synthesized through Friedel-Crafts-type substitution of the carbazole rings. These compounds were thermally and morphologically stable host materials for OLED applications. Efficient blue phosphorescent OLEDs were obtained when employing CBZ1-F2 as the host and FIrpic as the guest.

Improved synthesis of 2,2'-dibromo-9,9'-spirobifluorene and its 2,2'-bisdonor-7,7'-bisacceptor-substituted fluorescent derivatives.

Pure 2,2'-Dibromo-9,9'-spirobifluorene was synthesized by a method that did not involve troublesome dibromination of 9,9'-spirobifluorene or Sandmeyer reaction of 2,2'-diamino-9,9'-spirobifluorene. A series of donor-acceptor orthogonally substituted 9,9'-spirobifluorene was subsequently prepared showing rich variation of fluorescence in solution and in solid state. [reaction: see text]

Synthesis, characterization, and photophysical properties of Os(II) diimine complexes [Os(N(wedge)N)(CO)(2)I(2)] (N(wedge)N = bipyridine, phenanthroline, and pyridyl benzoxazole).

A new series of Os(II) diimine complexes with the general formula [Os(N(wedge)N)(CO)(2)I(2)], N(wedge)N = 2,2'-bipyridine (bpy) (1), 4,4'-di-tert-butyl-2,2'-bipyridine (dbubpy) (2), 4,7-diphenyl-1,10-phenanthroline (dpphen) (3), 2-(2'-pyridyl)benzoxazole (pboz) (4), and 5-tert-butyl-2-(2'-pyridyl)benzoxazole (bupboz) (5), were synthesized and characterized by spectroscopic methods and by a single-crystal X-ray diffraction study on the dpphen complex 3. The corresponding photophysical properties were studied using UV-vis and emission spectrometry. The resulting phosphorescence features both in solution and as a solid film, in combination with the MO calculation, lead us to conclude that the emissions originate from mixed halide-to-ligand (XLCT approximately 70%) and metal-to-ligand (MLCT approximately 30%) transitions instead of the typical MLCT transition.

Derivative of alpha,beta-dicyanostilbene: convenient precursor for the synthesis of diphenylmaleimide compounds, E-Z isomerization, crystal structure, and solid-state fluorescence.

A convenient and efficient procedure was developed for preparing 3,4-diaryl-substituted maleimides through the improved synthesized diaryl-substituted fumaronitrile. The synthesis of diphenyl-substituted fumaronitrile derivatives from phenylacetonitrile compounds was analyzed and improved. We found the stoichiometry of the sodium methoxide and the concentration of the starting material, phenylacetonitrile derivatives, were crucial for the high yield and easy purification of the products.

Readily synthesised arylamino fumaronitrile for non-doped red organic light-emitting diodes.

Bright (maximum 10034 cd m(-2), 455 cd m(-2) at 20 mA cm(-2)) and efficient (maximum 2.4% at 4 mA cm(-2)) red (lambda(max)el 634-636 nm) organic light-emitting diodes employ arylamino-substituted fumaronitrile as the novel host emitter, which is readily prepared and easily purified.