Silicon phthalocyanine-based n-type organic mixed ionic-electronic conductor in organic electrochemical transistors

Abstract

Phthalocyanines have evolved from their early role as dyes and pigments into a versatile class of small-molecule semiconductors used in thin-film electronics, including organic photovoltaics and thin-film transistors. Using a silicon phthalocyanine with hydrophilic (2-[2-(2-methoxyethoxy)ethoxy]acetate) axial substitutions, we report the first application of phthalocyanine films as an n-type organic mixed ionic-electronic conductor material in organic electrochemical transistors. The devices demonstrate a figure of merit (μC*) of 0.011 F cm⁻¹ V⁻¹ s⁻¹, volumetric capacitance (C*) of 79.3 F cm⁻³ and resulting charge mobility (μ) of 1.4 × 10⁻⁴ cm² V⁻¹ s⁻¹. Characterization of the films using atomic force microscopy and Raman spectroscopy points towards a rearrangement of the thin films post-swelling, which ultimately results in poor cycling stability. Nonetheless, this application broadens the use of phthalocyanines and enlarges the library of organic mixed ionic-electronic conductors to include this inexpensive and biocompatible material.