The ac electrical properties of monoclinic lithium phthalocyanine (LiPc) and of the iodinated compound LiPcI have been investigated in the frequency and temperature regimes 20 Hz≤ν≤1 GHz and 1.5 K≤T≤300 K, respectively. Both compounds are semiconductors with dielectric constants ε∞≊6 (LiPc) and 20 (LiPcI). Up to room temperature tunneling of charge carriers is the dominant conduction process in both compounds, yielding intrinsic dc conductivities σdc≊5.3×10−4 Ω−1 cm−1 (LiPc) and 0.2 Ω−1 cm−1 (LiPcI). The frequency and temperature dependence of the complex ac conductivity suggests polarons as the dominant species of charge carriers. The higher conductivity of the iodinated compound can be attributed to an enhanced mobility of the polaronic charge carriers which is most probably due to a better overlap of the π orbitals along the stacking direction of the molecules.
The ac electrical properties of monoclinic lithium phthalocyanine (LiPc) and of the iodinated compound LiPcI have been investigated in the frequency and temperature regimes 20 Hz≤ν≤1 GHz and 1.5 K≤T≤300 K, respectively. Both compounds are semiconductors with dielectric constants ε∞≊6 (LiPc) and 20 (LiPcI). Up to room temperature tunneling of charge carriers is the dominant conduction process in both compounds, yielding intrinsic dc conductivities σdc≊5.3×10−4 Ω−1 cm−1 (LiPc) and 0.2 Ω−1 cm−1 (LiPcI). The frequency and temperature dependence of the complex ac conductivity suggests polarons as the dominant species of charge carriers. The higher conductivity of the iodinated compound can be attributed to an enhanced mobility of the polaronic charge carriers which is most probably due to a better overlap of the π orbitals along the stacking direction of the molecules.