Tetra-methyl substituted copper (II) phthalocyanine as a hole injection enhancer in organic light-emitting diodes

Abstract

We have enhanced hole injection and lifetime in organic light-emitting diodes (OLEDs) by incorporating the isomeric metal phthalocyanine, CuMePc, as a hole injection enhancer. The OLED devices containing CuMePc as a hole injection layer (HIL) exhibited higher luminous efficiency and operational lifetime than those using a CuPc layer and without a HIL. The effect of CuMePc thickness on device performance was investigated. Atomic force microscope (AFM) studies revealed that the thin films were smooth and uniform because the mixture of CuMePc isomers depressed crystallization within the layer. This may have caused the observed enhanced hole injection, indicating that CuMePc is a promising HIL material for highly efficient OLEDs.

Evaluation of the Intramolecular Charge-Transfer Properties in Solvatochromic and Electrochromic Zinc Octa(carbazolyl)phthalocyanines

“…Phthalocyanines (Pcs) are planar macrocyclic compounds with extended 18 π-electron conjugated system that display unique electronic and optical properties. − Because of their fascinating properties as well as their thermal and chemical stability, Pcs were intensively studied as prospective compounds for photodynamic therapy (PDT) of cancer, − near-IR imaging agents, − organic-based solar cells, − and organic light-emitting diodes (OLEDs). − The aggregation behavior exhibited by the large and planar Pc macrocycles results in a drastic change of their optical properties, thus limiting their use in many applications. − For example, such undesired behavior can greatly affect the PDT activity and nonlinear optical properties by reducing the active absorbing excited-state lifetime. , Therefore, the large architectural flexibility characterized by the Pc structure can be exploited to tune the molecular properties in pursuit of optimized optical features (color, aggregation, optical absorption, etc.) for the required applications.…”

Tetraalkyl-substituted zinc phthalocyanines used as anode buffer layers for organic light-emitting diodes*

“…[8,9] Since the first demonstration of the use of copper phthalocyanine (CuPc) to modify the ITO anode of an OLED by Tang and VanSlyke in 1996, [5] the use of metal phthalocyanines (MPcs) as anode buffer layers has been subject to intensive investigation with the aim of achieving higher OLED efficiencies and stabilities. [5,9,10,[25][26][27][28][29][30] In most cases, these MPc layers are fabricated via the vacuum sublimation method because of the poor solubility of typical MPcs in organic solvents. [5,25,30] While vacuum processing eases the fabrication of complex OLED configurations with the desired performance and high reliability on a laboratory scale, this approach is very costly because of the expense of maintaining an ultrahigh vacuum combined with its high energy consumption, high operating temperatures, and huge materials losses.…”

Fabrication of organic light-emitting diode using molybdenum trioxide interlayer between electrode and organic interface

“…Akanksha Uniyal and Poornima Mittal [23] provide a comparison of the bilayer and multilayer OLED. Yu-Long Wang et al [24] used tetramethyl substituted copper (II) phthalocyanine as a hole-injection enhancer in OLED. More recently, Xu et al [25] developed a multilayer transparent conducting electrodes for OLEDs, while Meiling Shan et al [26] reported an enhanced hole injection in OLEDs utilizing a copper iodidedoped hole-injection layer.…”