A study is presented of the formation and optical properties of polymeric heterostructures from poly(p-phenylene vinylene) (PPV) and poly(o-methoxyaniline) (POMA) produced via the self-assembly technique. POMA layers were obtained in a non self-limiting process from its emeraldine salt, semiconducting form in HCl solution. Thermal conversion of PPV was performed at low temperatures with the substitution of the counter-ion Cl in the PPV precursor by a long sulfonic chain, the dodecylbenzenesulfonate (DBS) ion. The optical properties of PPV films converted in this way are not affected by POMA, which can be used as transparent electrode of PPV luminescent devices.

A brief review is provided of the ways electrical properties of semiconducting polymers can be exploited. Emphasis is given to the analysis of electrical conductivity data, in particular to the importance of interchain processes that must be considered along with intrachain processes for bulk conductivity. Among the large variety of possible applications of thin films of semiconducting polymers, the focus is placed on recent breakthroughs in producing diodes, field effect transistors and electroluminescent devices out of these materials. The fabrication of ultrathin films from semiconducting polymers, using the Langmuir-Blodgett and the self-assembly techniques, is discussed to illustrate the importance of processibility issues for any real application including these polymers.

RESUMO: Esse artigo apresenta resultados sobre fabricação e caracterização de um transistor por efeito de campo (FET) tendo a poli(o-metoxianilina) - POMA - como material ativo. Uma adaptação de processos de microeletrônica tradicional foi feita para a confecção desse dispositivo. O FET desenvolvido apresentou modulação por voltagem de porta Vg, mas operou mesmo em Vg=0. A corrente de dreno I D aumentou significativamente sob iluminação na região da radiação visível e infravermelho próximo, mostrando o caráter fotocondutor da POMA dopada e, portanto, do dispositivo. Um modelo teórico baseado nos mecanismos de condução eletrônica da POMA, e de efeitos de interface metal-polímero foi elaborado, ajustando-se muito bem aos resultados experimentais.

ABSTRACT: A field effect transistor - FET made from poly(o-methoxyaniline) (POMA), which is a conductive polymer, was developed. Several modifications were carried out to adapt the procedures generally used in traditional device developments. The characteristic of the FET produced was sensible to the gate modulation, but it operates even for V G = 0. The drain current I D enhanced under visible and near infrared radiation, showing the photoconductor character of POMA and, consequently, of the device. A theoretical model, based on the electronic properties of POMA and on the metal-polymer interface, was developed which is in good agreement with the experimental results.