Conductivity and thermal properties of N-alkylated-heterocyclic compound-TCNQ complex salts and application to organic capacitor

7,7,8,8-Tetracyanoquinodimethane (TCNQ) was complexed with alkylated heterocyclic compound to evaluate the conductivity and melting point. Pyridine, quinoline, iso-quinoline, acridine, picoline and 3-methyl quinoline were quaternized by n-alkyl iodide to prepare electron-donating compounds. Among a series of complex salts, hexylpyridinium— and butyl-iso-quinolinium-TCNQ complex salts showed high conductivity of 4.3 × 10−1 and 2.2 × 10−2 S cm−1, respectively. There was a large temperature difference between melting point and decomposition point of about 50°C for these complex salts. These conductive complex salts were strongly suggested as potential candidates for the basic material to construct an effective capacitor. All solid-state capacitor (5 mm φ × 10 mm h) composed of Al/TCNQ complex salt/Al2O3 insulator/Al showed an electric capacity of 7–8 μF.