Zinc-porphyrin dyes with different meso-aryl substituents for dye-sensitized solar cells: experimental and theoretical studies.

A series of new zinc-porphyrin dyes that contain different meso substituents (phenyl, carbazole phenyl, and carbazole thiophenyl groups) and bithiophenyl cyanoacrylic acid as the π-conjugated anchoring moiety were designed, synthesized, and characterized as sensitizers for dye-sensitized solar cells (DSSCs). The effects of these meso substituents on the properties of the porphyrin dyes were theoretically and experimentally investigated. By meso substitution of the porphyrin ring with carbazole-aryl moieties, the short-circuit current (Jsc ) and open-circuit voltage (Voc ) of the DSSCs were improved as was the power conversion efficiency (η) owing to the influence of both the suppression of dye aggregations and the enhanced charge separation and charge-injection efficiency of the dye to TiO2 films. Among these dyes, ZnPCPA made of the carbazole phenyl meso substituents gave rise to the highest η of 6.24 % (Jsc =13.38 mA cm(-2) , Voc =0.66 V, and fill factor of 0.71).

Novel bis[5-(fluoren-2-yl)thiophen-2-yl]benzothiadiazole end-capped with carbazole dendrons as highly efficient solution-processed nondoped red emitters for organic light-emitting diodes.

A series of novel red-emitting bis[5-(fluoren-2-yl)thiophen-2-yl]benzothiadiazole-cored dendrimers containing carbazole dendrons up to the third generation are synthesized. Their photophysical, thermal, electrochemical, and electroluminescent properties as nondoped solution-processed red light-emitters for OLEDs are investigated. By using carbazole dendrons as the end caps, we are able to reduce the crystallization and retain the high emissive ability of a planar fluorescent core in the solid state as well as improve the thermal stability of the material. These dendrimers show a bright-red fluorescence and can form morphologically stable amorphous thin films with glass-transition temperatures as high as 283 °C. Simple structured solution-processed OLEDs using these materials as hole-transporting nondoped emitters and BCP as the hole-blocking layer emit a stable red color around 622-645 nm, with high luminance efficiencies (up to 4.80 cd A(-1) at 1.2 mA cm(-2)) and CIE coordinates of (0.65, 0.33), which are close to the pure red color.

Novel bis(fluorenyl)benzothiadiazole-cored carbazole dendrimers as highly efficient solution-processed non-doped green emitters for organic light-emitting diodes.

Bis(fluorenyl)benzothiadiazole-cored carbazole dendrimers show high thermal and electrochemical stability, and great potential as solution processed hole-transporting non-doped green emitters for OLEDs. A pure green device with CIE coordinates of (0.27, 0.62) and high luminance efficiencies (up to 10.01 cd A(-1)) is achieved, respectively.

Bis(carbazol-9-ylphenyl)aniline end-capped oligoarylenes as solution-processed nondoped emitters for full-emission color tuning organic light-emitting diodes.

A series of bis(3,6-di-tert-butylcarbazol-9-ylphenyl)aniline end-capped oligoarylenes, BCPA-Ars, are synthesized by double palladium-catalyzed cross-coupling reactions. By using this bis(carbazol-9-yl)triphenylamine moiety as an end-cap, we are able to reduce the crystallization and retain the high-emission ability of these planar fluorescent oligoarylene cores in the solid state, as well as improve the amorphous stability and solubility of the materials. The results of optical and electrochemical studies show that their HOMOs, LUMOs, and energy gaps can be easily modified or fine-tuned by either varying the degree of π-conjugation or using electron affinities of the aryl cores which include fluorene, oligothiophenes, 2,1,3-benzothiadiazole, 4,7-diphenyl-4-yl-2,1,3-benzothiadiazole, and 4,7-dithien-2-yl-2,1,3-benzothiadiazole. As a result, their emission spectra measured in solution and thin films can cover the full UV-vis spectrum (426-644 nm). Remarkably, solution-processed nondoped BCPA-Ars-based OLEDs could show moderate to excellent device performance with emission colors spanning the whole visible spectrum (deep blue to red). Particularly, the RGB (red, green, blue) OLEDs exhibit good color purity close to the pure RGB colors. This report offers a practical approach for both decorating the highly efficient but planar fluorophores and tuning their emission colors to be suitable for applications in nondoped and solution-processable full-color emission OLEDs.

An efficient solution processed non-doped red emitter based on carbazole-triphenylamine end-capped di(thiophen-2-yl)benzothiadiazole for pure red organic light-emitting diodes.

New carbazole-triphenylamine end-capped di(thiophen-2-yl)benzothiadiazole showed high thermal and electrochemical stability, and great potential as a solution processed hole-transporting non-doped red emitter for OLEDs. A pure red device with CIE coordinates and a high luminance efficiency of (0.66, 0.33) and 3.97 cd A(-1), respectively, was achieved.

Carbazole dendronised triphenylamines as solution processed high Tg amorphous hole-transporting materials for organic electroluminescent devices.

Carbazole dendrimers up to 4th generation were synthesized. They showed significantly high T(g), amorphous and stable electrochemical properties, and great potential as solution processed hole-transporting materials for OLEDs. Alq3-based green devices exhibited high luminance efficiency and CIE coordinates of 4.45 cd A(-1) and (0.29, 0.53), respectively.

Bifunctional anthracene derivatives as non-doped blue emitters and hole-transporters for electroluminescent devices.

New highly fluorescent bifunctional anthracenes showed high thermal and electrochemical stability, and great potential as both blue emitters and hole-transporters for OLEDs. Deep-blue and Alq3-based green devices with maximum efficiencies and CIE coordinates of 1.65 and 6.25 cd A(-1), and (0.15, 0.16) and (0.26, 0.49) were achieved, respectively.