Fabrication of Hybrid Membranes Containing Nylon-11 and Organic Semiconductor Particles with Potential Applications in Molecular Electronics

Abstract

Chemical degradation is a major disadvantage in the development of organic semiconductors. This work proposes the manufacture and characterization of organic semiconductor membranes in order to prevent semiconductor properties decreasing. Semiconductor membranes consisting of Nylon-11 and particles of π-conjugated molecular semiconductors were manufactured by high-vacuum evaporation followed by thermal relaxation. Initially, and with the aim of obtaining semiconductor particles, bulk heterojunction (BHJ) was carried out using green chemistry techniques between the zinc phthalocyanine (ZnPc) and the zinc hexadecafluoro-phthalocyanine (F₁₆ZnPc) as n-type molecular semiconductors with the p-type molecular semiconductor dibenzotetrathiafulvalene (DBTTF). Consequently, the π-conjugated semiconductors particles were embedded in a Nylon-11 matrix and characterized, both structurally and considering their optical and electrical properties. Thin films of these materials were manufactured in order to comparatively study the membranes and precursor semiconductor particles. The membranes presented bandgap (E_g) values that were lower than those obtained in the films, which is an indicator of an improvement in their semiconductor capacity. Finally, the membranes were subjected to accelerated lighting conditions, to determine the stability of the polymer and the operating capacity of the membrane. After fatigue conditions, the electrical behavior of the proposed semiconductor membranes remained practically unaltered; therefore, they could have potential applications in molecular electronics. The chemical stability of membranes, which did not degrade in their polymer compound, nor in the semiconductor, was monitored by IR spectroscopy.

Keywords: high-vacuum evaporation; molecular semiconductor; optoelectronic properties; semiconductor membrane; thin film.

Figure 1

Molecular structure for: (a) ZnPc, (b) F₁₆ZnPc, (c) DBTTF and (d) IR spectrum for ONs.

Figure 2

(a) X-ray diffraction patterns of the two thin films, and SEM images of (b) ONs-1 and (c) ONs-2 films at 500x magnification.

Figure 3

SEM images of (a) membrane-1 at 500x, (b) membrane-1 at 5000x, (c) membrane-2 at 500x, and (d) membrane-2 at 5000x magnification.

Figure 4

(a) Schematic structure of the electrical measurements on membranes and J-V characteristic of (b) ONs-1 and (c) ONs-2 films.

Figure 5

J-V characteristic of (a) ONs-1 film and membrane-1 and (b) ONs-2 film and membrane-2.

Figure 6

J-V characteristic of (a) membrane-1 and (b) membrane-2, compared in natural light and darkness conditions. (c) IR spectrum for membrane after irradiation.

Figure 7

Plot of (αhν)1/2 vs. photon energy of the (a) ONs-1 film and membrane-1, (b) ONs-2 film and membrane-2, and Photoluminescence spectra of (c) films and (d) membranes.