Engineered doping of organic semiconductors for enhanced thermoelectric efficiency

Significant improvements to the thermoelectric figure of merit ZT have emerged in recent years, primarily due to the engineering of material composition and nanostructure in inorganic semiconductors (ISCs). However, many present high-ZT materials are based on low-abundance elements that pose challenges for scale-up, as they entail high material costs in addition to brittleness and difficulty in large-area deposition. Here we demonstrate a strategy to improve ZT in conductive polymers and other organic semiconductors (OSCs) for which the base elements are earth-abundant. By minimizing total dopant volume, we show that all three parameters constituting ZT vary in a manner so that ZT increases; this stands in sharp contrast to ISCs, for which these parameters have trade-offs. Reducing dopant volume is found to be as important as optimizing carrier concentration when maximizing ZT in OSCs. Implementing this strategy with the dopant poly(styrenesulphonate) in poly(3,4-ethylenedioxythiophene), we achieve ZT=0.42 at room temperature.clos

Nanomaterials: electromagnetic wave energy loss

The utilization of electromagnetic (EM) wave energy for various appliances and tools in GHz frequency range, in accordance to the development of advanced technology, is rapidly progressing. Simultaneously, the development and research related to EM wave absorbing/shielding materials is also growing fast, in order to cut off and to defend human beings and electronic devices from excessive or unnecessary EM radiation exposure. Nanomaterials is one of the ideal EM wave absorber material, due to their properties such as lightweight, remarkable electrical properties, strongly absorb EM waves, possess tunable absorption frequency, and multifunctionality. This chapter provides introduction of EM wave absorbers; introduction of EM wave energy loss that is highly associated with EM wave absorption performance; discussion on influence factors that affect EM wave absorption capability; and reviews on research and fabrication process of nanomaterials related to EM wave absorber

Conducting Polymer Nanomaterials and Their Applications

A paradigm shift takes place in the fabrication of conducting polymers from bulky features with microsize to ultrafine features with nanometer range. Novel conducting polymer nanomaterials require the potential to control synthetic approaches of conducting polymer on molecular and atomic levels. In this article, the synthetic methodology of conducting polymer has been briefly considered with chemical oxidation polymerization and electrochemical polymerization. The recent achievements in the fabrication of conducting polymer nanomaterials have been extensively reviewed with respect to soft template method, hard template method and template-free method. It also details the morphological spectrum of conducting polymer nanomaterials such as nanoparticle, core-shell nanomaterial, hollow nanosphere, nanofiber/nanorod, nanotube, thin film and nanopattern and nanocomposite. In addition, their applications are discussed under nanometer-sized dimension.This work has been financially supported by the Brain Korea 21 program of the Korean Ministry of Education and the Hyperstructured Organic Materials Research Center supported by Korea Science and Engineering Foundation