Vapor phase infiltration (VPI) and doping of conducting polymers

Abstract

In this thesis, the "Vapor Phase infiltration"(VPI), a vacuum based process derived from the atomic layer deposition (ALD), is used for the top-down infiltration and doping of various conducting polymers. In the first part of this thesis, a single precursor vapor phase infiltration (VPI) process to dope polyaniline (PANI) is presented. As dopants, the vaporized Lewis acidic precursors SnCl4 and MoCl5 were used at a process temperature of 150 °C. After 100 cycles, the MoCl5-infiltrated PANI showed the highest conductivity, 2.93 × 10-4 S/cm, which is a significant enhancement of up to 6 orders of magnitude in comparison to undoped PANI. SnCl4-infiltrated PANI showed highest conductivity after 60 cycles with a value of 1.03 × 10-5 S/cm. The second part of this thesis describes the single precursor VPI and doping of poly(3-hexyl)thiophene (P3HT). For the infiltration processes, the Lewis acid MoCl5 was used as precursor at a process temperature of 70ºC. The room-temperature I-V plots show a dependency on the VPI cycles numbers. The highest values show an increase of 5 orders of magnitude for the conductivity, namely from 1.44 x 10-5 S/cm in the as prepared P3HT to 3.01 S/cm after infiltration 100 cycles In the last part of this thesis, the multiple pulsed vapor phase infiltration (MPI) process was applied to dope polyaniline (PANI). For the process, the two typical ALD precursors diethylzinc (DEZ) and deionized water (H2O) were used at a process temperature of 155ºC. The room-temperature I-V polts showed the conductivity of Zn-infiltrated PANI increasing to 18.42 S/cm, up to three orders of magnitude higher than obtained upon conventional doping with 1 M HCl in wet-chemical ways (8.23 x 10-2 S/cm).