Ambipolar Organic Thin Film Transistor-like Behavior of Cationic and Anionic Phthalocyanines Fabricated Using Layer-by-Layer Deposition from Aqueous Solution

Abstract

Organic thin film field effect transistors of water-soluble cationic and anionic phthalocyanine derivatives were successfully prepared using the layer-by-layer deposition technique. The alternating film growth and subsequent transistor properties were studied with a variety of techniques including ellipsometry, UV−vis spectroscopy, polarized UV−vis spectroscopy, AFM, and field effect transistor measurements. A stepwise and regular deposition of copper(II) phthalocyanine tetrakis(methyl pyridinium) chloride and copper(II) phthalocyanine tetrasulfonic acid, tetrasodium salt multilayers in both pure water and 0.03 M NaCl solution was observed. Differences in linear growth were observed between pure water and 0.03 M NaCl-based solutions. Polarized UV−vis spectra indicated that the conjugated phthalocyanine ring lies almost flat on the substrate surface with a random orientation within the plane of the substrate. Unusual “ambipolar” transistor-like behavior was found for the films that can be attributed to an ion-modulated electrical conduction mechanism, which relies on the assistance of mobile ions to stabilize the oxidized or reduced species in the channel region.

Effects of humidity on the electrical properties of thermal inkjet-printed films of copper tetrasulfonated phthalocyanine (CuTsPc) onto paper substrates

“…Nevertheless, despite the good perspectives for TsPcbased electronics, the number of reports related to this topic is rather limited [6,[18][19][20][21][22][23], principally involving the production of devices using printing methods [22,23]. Most of applications exploiting the water solubility of TsPc molecules are based on layer-by-layer (LbL) assembly for sensors [19,[24][25][26].…”

Thermal inkjet printing of copper tetrasulfonated phthalocyanine (CuTsPc) as a semiconducting layer on flexible MIS capacitors

“…Sulfonated-substituted phthalocyanines have been exploited mainly in OFETs [27][28][29] and OPVs [4][5][6]30 . Regarding OFETs, Locklin et al 27 have produced devices with ambipolar-like behavior using the layer-by-layer (LbL) technique to assemble thin films of cationic and anionic copper phthalocyanine derivatives.…”

“…Regarding OFETs, Locklin et al 27 have produced devices with ambipolar-like behavior using the layer-by-layer (LbL) technique to assemble thin films of cationic and anionic copper phthalocyanine derivatives. Thermal inkjet-printing of copper tetrasulfonated phthalocyanine (CuTsPc) films containing polyvinyl alcohol (PVA) plasticizer were used to fabricate flexible metal-insulator-semiconductor (MIS) capacitors using anodic aluminum oxide (Al 2 O 3 ) as the insulating layer.…”

Ambipolar Blends of Cu‐Phthalocyanine and Fullerene: Charge Carrier Mobility, Electronic Structure and their Implications for Solar Cell Applications

“…Recently, such donor-acceptor mixtures have been implemented also in organic field-effect transistors (OFETs). Ambipolar OFETs have been realized with a variety of material combinations, including polymer/fullerene blends [6], mixtures of soluble oligomers [7] as well as evaporated molecular hetero-layer structures and mixed layers [8].…”