Electrical properties of a series of carbazole polymers

Abstract

The electrical transport properties of three vinyl carbazole polymers have been examined to determine if the observed variations in NMR chemical shifts resulting from inter−ring shielding effects could be correlated with carrier mobilities in the polymers. Drift mobilities were measured in films of the polymers overcoated with thin layers of amorphous Se using a xerographic discharge technique. Under the conditions for observing trap free space charge limited currents the hole mobilities were calculated from Child’s law. The three polymers exhibited mobilities varying as the square of the electric field over the range of fields examined. P2VK which showed the overall largest upfield shift of the aromatic protons exhibited a mobility of 1.4×10−6 cm2/V⋅sec at a field of 4×105 V/cm. PVK which exhibit an intermediate degree of shielding had a mobility of 1.4×10−7 cm2/V⋅sec and P3VK which exhibits the smallest shielding effect had a mobility of 2.4×10−8 cm2/V⋅sec both at equivalent fields. Although P2VK showed the highest mobility it also accumulated the largest amount of trapped charge. At present not enough is known about the detailed microstructure of the polymers to identify the reason for this phenomon.

Synthesis of n‐alkyl methacrylate polymers with pendant carbazole moieties and their derivatives

“…PVK was found to utilize pendant carbazole groups as the main charge carrier and has been shown to have high hole mobility . It initially found prominence as a highly photosensitive organic conductor and was extensively studied by the Xerox Corporation primarily due to its role in electrophotography leading to further understanding of the charge transport properties and excimer formation . The charge transport of PVK is based on the pendant carbazole groups, thus their alignment and spatial proximity is key for efficient charge mobility.…”

“…The charge transport of PVK is based on the pendant carbazole groups, thus their alignment and spatial proximity is key for efficient charge mobility. The importance of the carbazole spacing was demonstrated by chemically altering the polymer to adjust the alignment of the carbazole groups resulting in varied electrical properties . Therefore, conformational changes in the carbazole groups allow for the alteration of conductivity in the polymer leading to the development of resistive memory applications using pendant carbazole groups …”

Controlled Synthesis of Poly(N-ethyl-3-vinylcarbazole) and Block Copolymers via RAFT Polymerization

“…N -Ethyl-3-vinylcarbazole (E3VC), which can be regarded as a styrene derivative, was chosen as a carbazole-containing monomer because the carbazole unit is directly bound to the polymer main chain formed after the polymerization. Poly(E3VC) was reported to be synthesized by cationic polymerization with a boron trifluoride initiator, , while detailed investigation of the polymerization behavior was not given. The direct linkage of the carbazole unit to the polymer main chain is an important feature of this monomer because it may affect not only the polymerization behavior but also electronic and photonic properties.…”

Carbazole Derivatized n‐Alkyl Methacrylate Polymeric Memristors as Flexible Synaptic Substitutes

“…In these polymers, charge carriers are assumed to have a higher intra‐ & inter‐chain mobility when the overlapping of related orbitals is large between two adjacent carbazoles. [ 27,28 ] The transition from a bistable to a continuously variable response is due to the increased flexibility of the pendant carbazoles. Achieving this overlap is directly related to the local electric field that the moieties experience that force them to adopt an overlapping conformation, as well as their rotational activation energy.…”