Newly synthesised gadolinium bis-phthalocyanine sandwich complex: ambipolar organic semiconductor

Abstract

Time of flight photocurrent transient studies on 5 μm thick solution processed films of novel non-peripherally octa-octyl-substituted liquid crystalline gadolinium bis-1,4,8,11,15,18,22,25octakis(octyl) phthalocyanines (8GdPc 2 ) provide a quantitative analysis of the intrinsic ambipolar charge transport relative to mesomorphic structure of this lanthanide compound. Characteristic liquid crystalline phases of these molecules have been identified from differential scanning calorimetry supported by observation from the UV-visible absorption, showing crystal-columnar mesophase and columnar mesophase-isotropic liquid transitions at 64.2 °C and 162 °C, respectively. The TOF carrier mobility is found to be structure dependent and highest values of 4.73×10 −6 m 2 V −1 s −1 and 1.6×10 −6 m 2 V −1 s −1 have been estimated for hole and electron mobilities for hexagonally packed, columnar structures of the spin-coated films. These results are exploitable for development of single molecule based all organic complimentary analogue and digital circuits with tunable field effect performance.

Charge Mobility in Discotic Liquid Crystals

“…Besides triphenylene, other molecular systems were studied in recent years, such as those based on triindole [ 208 , 209 ], phthalocyanine [ 125 , 210 ], thiophene [ 211 , 212 ] and truxenone [ 213 , 214 ] cores, or on particular molecular architectures, such as dendrons [ 174 , 176 , 215 , 216 ]. Nakawa and coworkers reported the study of the mesomorphic and mobility properties of a blend of 1,4,8,11,15,18,22,25-octahexylphthalocyanine (C6PcH2) with its analogue 1,4,8,11,15,18,22,25-octahexyltetrabenzotriazaporphyrin (C6TBTAPH2) [ 125 ].…”

Ambipolar Discotic Liquid Crystals Built Around Platinum Diimine‐Dithiolene Cores

“…The number of ambipolar DLC systems built around metal complexes remains scarce. The only examples involve gadolinium or zinc phthalocyanines and, very recently, ambipolar carrier mobility was noted for a series of liquid crystalline platinum(II) complexes with 2‐phenylpyridine derivatives as the main ligand and 5‐substituted tetrazole as the auxiliary ligand …”

Channel length-dependent characterisations of organic thin-film transistors with solution processable gadolinium phthalocyanine derivatives

“…2. This compound shows the crystal-columnar mesophase and columnar mesophase-isotropic liquid transitions at 64.2 °C and 162 °C, respectively [22] and, therefore, the spectrum of the as-deposited film which exhibits absorptions at ~ 390, 475, 640 and 730 nm is characteristic of the crystal (K) structure [20]. The broad band at ~ 390 nm is assigned to the Soret band (π-π*) and the two broad bands, at ~ 640 and 730 nm are the characteristics Q-band, split into Q x [b 1u (π) → e g (π*)] and Q y [a 2u (π) → e g (π*)], respectively.…”