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Received Oct 18, 2017; Revised Jan 11, 2018; Accepted Feb 7, 2018
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1. Introduction
Organic semiconductors have witnessed considerable development in recent years, with increasing research activity on this class of materials and their potential applications. The interest in this area is to obtain new organic compounds with improved, more efficient properties for the manufacture of organic, light-emitting diodes (OLEDs) [1], organic photovoltaic cells (OPVs) [2, 3], and thin film transistors (TFTs) [4]. The biosynthesis of new hybrid structures using natural organic compounds for development of photoreactive compounds is straightforward and significantly reduces the cost of organic devices.
Cochineal insects (Dactylopius coccus C.) from the city of Loja, Ecuador, were used here to form a new hybrid structure. Cochineal is not only the main red dye used in Central America, but it was also used in Ecuador and Peru by the Incas, before the Spanish conquest. Cochineal is made up of 80% carminic acid (CA). In the 16th century, it was exported to Europe and began to replace the domestic kermes insect (Kermes vermilio) [5, 6]. Cochineal insects are nowadays widely used in the food industry to replace synthetic colorants, and its antioxidant properties have been well known for a long time [7, 8].
In this study, we observed the increased UV-Vis spectral absorbance and electrical conductivity of the natural pigment through biosynthetic silver nanoparticles [5]. To improve the optical and electrical properties of cochineal, it was used as the reducing agent during the biosynthesis of silver nanoparticles (AgNPs) without submitting the cochineal to any kind of separation of its primary compounds. The cochineal extract was used as the reducing agent for the biosynthesis of AgNPs, since green synthesis of the AgNPs has been an easy, affordable, inexpensive technique and is potentially not harmful to human health and the environment [9–14]. Different volumes of cochineal dye (pH = 12, [5]) in 1 ml of AgNO3 solution (10 mM, pH = 5.6) were analyzed with UV-Vis spectrometry, Commission Internationale de l’Eclairage (CIE) chromaticity diagram, cyclic voltammetry (CV), scanning transmission electron microscopy (STEM), energy dispersive X-ray spectroscopy (EDS),...