Search query: Organic Semiconductors for Thermoelectric Applications

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abstract: The thermoelectric performance of thin films fabricated from two commercially available, highly conductive polymer formulations based on poly (3,4 ethylendioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) was investigated. In order to enhance the electrical conductivity, the high boiling solvent dimethyl sulfoxide (DMSO) was added. By changing the content of DMSO the electrical conductivity was increased by a factor of two without changing the Seebeck coefficient or the thermal conductivity. We achieved ZT 9.2 x 10 3 at room temperature upon the addition of 5 vol. DMSO to the PEDOT:PSS formulation.
author_names: M Scholdt

Hung Manh Do

John F Lang

Andre Gall

Alexander Colsmann

Uli Lemmer

Jan D Koenig

Mark T Winkler

Harald Dr Boettner
title: Organic Semiconductors for Thermoelectric Applications
year: 2010

abstract: Doping is essential to manipulate the electrical performance of both thermoelectric (TE) materials and organic semiconductors (OSCs) Although organic thermoelectric (OTE) materials have experienced a rapid development over the past decade, the chemical doping of OSCs for TE applications lags behind, which has limited further breakthroughs in this cutting edge field. Recently, increasing efforts have been devoted to the development of energetically matched host and dopant molecules, exploring novel doping methods and revealing the doping mechanisms. This tutorial review covers the basic mechanisms, fundamental requirements, recent advances and remaining challenges of chemical doping in OSCs for TE applications. We first present the basic knowledge of the trade off relationship in TE materials and its critical requirements for doped OSCs, followed by a brief introduction of recent advances in the molecular design of OSCs and dopants. Moreover, we provide an overview of the existing categories of doping mechanisms and methods, and more importantly, emphasize the summarized doping strategies for the state of the art OTE materials. Finally, challenges and perspectives on the chemical doping of OSCs are proposed to highlight the research directions that deserve attention towards a bright future of OTE materials.
author_names: Wenrui Zhao

Jiamin Ding

Ye Zou

Chong-an Di

Daoben Zhu
title: Chemical doping of organic semiconductors for thermoelectric applications.
venue: Chemical Society reviews
year: 2020

abstract: First principles band structure calculations coupled with the Boltzmann transport theory are used to study the thermoelectric properties in pentacene and rubrene crystals. In the constant relaxation time and rigid band approximations, the electronic contribution to the Seebeck coefficient is obtained. The absolute value of Seebeck coefficient and its temperature and carrier density dependences are in quantitative agreement with the recent field effect modulated measurement. The dimensionless thermoelectric figure of merit is further evaluated based on the calculated transport coefficients and experimental parameters. The peak values of figure of merit in pentacene fall in the range of 0.8 1.1, which are close to those of the best bulk thermoelectric materials. Our investigations show that organic semiconductors can be potentially good thermoelectric materials for near room temperature applications.
author_names: Dong Wang

Ling Tang

Mengqiu Long

Zhigang Shuai
title: First principles investigation of organic semiconductors for thermoelectric applications.
venue: The Journal of chemical physics
year: 2009

abstract: We have predicted that organic semiconductor crystals with several percent carrier doping might show a considerable thermoelectric effect caused by transition in conduction mechanism from hopping to band like[1] Figure 1 shows the simulated density of states of thin film phase pentacene which shows narrowing of HOMO states as the temperature is lowered due to decreased thermal motion of the molecule. If the carriers are chemically doped to the organic semiconductors, it can be expected that the narrowing will lead to the shift in the Fermi energy which can be estimated as
author_names: Yuji Ikuta

Yuya Tsuchida

Naoki Muraya

Taro Nagahama

Toshihiro Shimada
title: Bulk crystal growth of organic semiconductors for thermoelectric applications
year: 2011

abstract: Organic thermoelectric (OTE) materials have attracted intensive attention because of their promising applications in flexible electricity generators and ultrathin solid cooling elements. The well d.
author_names: Fengjiao Zhang

Chong-an Di
title: Exploring Thermoelectric Materials from High Mobility Organic Semiconductors
year: 2020

abstract: Unlike the conventional p doping of organic semiconductors (OSCs) using acceptors, here, an efficient doping concept for diketopyrrolopyrrole based polymer PDPP[T]2 EDOT (OSC 1) is presented using an oxidized p type semiconductor, Spiro OMeTAD(TFSI)2 (OSC 2) exploiting electron transfer from HOMOOSC 1 to HOMOOSC 2 A shift of work function toward the HOMOOSC 1 upon doping is confirmed by ultraviolet photoelectron spectroscopy (UPS) Detailed X ray photoelectron spectroscopy (XPS) and UV vis NIR absorption studies confirm HOMOOSC 1 to HOMOOSC 2 electron transfer. The reduction products of Spiro OMeTAD(TFSI)2 to Spiro OMeTAD(TFSI) and Spiro OMeTAD is also confirmed and their relative amounts in doped samples is determined. Mott Schottky analysis shows two orders of magnitude increase in free charge carrier density and one order of magnitude increase in the charge carrier mobility. The conductivity increases considerably by four orders of magnitude to a maximum of 10 S m 1 for a very low doping ratio of 8 mol% The doped polymer films exhibit high thermal and ambient stability resulting in a maximum power factor of 0.07 uW m 1 K 2 at a Seebeck coefficient of 140 uV K 1 for a very low doping ratio of 4 mol% Also, the concept of HOMOOSC 1 to HOMOOSC 2 electron transfer is a highly efficient, stable and generic way to p dope other conjugated polymers.
author_names: Mahima Goel

Marie Siegert

Gert Krauss

John Mohanraj

Adrian Hochgesang

David C Heinrich

Martina Fried

Jens Pflaum

Mukundan Thelakkat
title: HOMO HOMO Electron Transfer: An Elegant Strategy for p Type Doping of Polymer Semiconductors toward Thermoelectric Applications.
venue: Advanced materials
year: 2020

abstract: Abstract Thermoelectrics currently attracts considerable attention as a promising branch in the field of organic electronics, with the prospect that organic semiconductors (OSCs) allow the development of light, flexible, and inexpensive thermoelectric devices, which act as alternative power sources, generating electricity from heat gradients. Thermoelectric generators are solid state devices that convert heat directly to electricity. They do not contain any moving parts and are able to operate over an extended period of time, and furthermore can function with small heat sources and limited temperature differences, which facilitates their use in situations where traditional engines are not feasible. The absence of moving parts, low need for maintenance, and a large variety of possible device architectures render organic thermoelectrics attractive for numerous applications, ranging from waste heat recovery to wearable textiles. In this chapter, we give a short introduction to the fundamentals of the thermoelectric effect, as well as to the design principles for thermoelectric generators and their characterization. Furthermore, we discuss the role of doping (i.e. the introduction of charge carriers through the addition of dopant molecules) and of the nanostructure and present strategies for the optimization of the thermoelectric properties of OSCs. Finally, we give an overview of processing methods and point out major achievements, as well as the remaining challenges.
author_names: Anna I Hofmann

Renee Kroon

Christian Muller
title: Doping and processing of organic semiconductors for plastic thermoelectrics
year: 2019

abstract: Thermoelectric materials with stable mechanical and chemical properties at high temperature are required for power generation applications. For example, gas temperatures up to 1000degC are normally present in the waste stream of industrial processes and this can be used for electricity generation. There are few semiconductor materials that can operate effectively at these high temperatures. One solution may be the use of wide bandgap materials, and in particular GaN based materials, which may offer a traditional semiconductor solution for high temperatures thermoelectric power generation. In particular, the ability to both grow GaN based materials and fabricate them into devices is well understood if their thermoelectric properties are favorable. To investigate the possibility of using III Nitride and its alloys for thermoelectric applications, we synthesized and characterized room temperature thermoelectric properties of metal organic chemical vapor deposition grown GaN and InGaN with different carrier concentrations and indium compositions. The promising value of Seebeck coefficients and power factors of Si doped GaN and InGaN indicated that these materials are suitable for thermoelectric applications.
author_names: Bahadir Kucukgok

Qinyue He

A Carlson

Andrew Geier Melton

Ian T Ferguson

Na Lu
title: Investigation of Wide Bandgap Semiconductors for Thermoelectric Applications
year: 2013

abstract: The feasibility of using organic thermoelectric devices to power sensors for different applications is a critical area of interest for researchers. Organic semiconductors possess lower thermoelectric performance than their inorganic counterparts, however, this can be compensated for by certain advantages, such as their light weight, low fabrication costs, and low fabrication temperatures. For practical applications, they face competition with Li ion batteries, which are known for their high energy densities and long lifetimes. Thus, in addition to having a suitable corresponding power output, ideal organic thermoelectric devices require excellent stability. In this study, such a perspective was examined via primarily focusing on recent studies of organic thermoelectric devices and, particularly, their practical applications. The impact of contact resistance on device performance has been discussed, together with suggestions of certain promising device structures for organic thermoelectric devices. Experimentally, it was confirmed that light and compact organic thermoelectric devices with a size of ~10 cm2 should be sufficiently suitable to power sensors. Moreover, these devices were confirmed to operate under natural cooling conditions without a heat sink, thus showing excellent stability for >70 days under continuous working conditions at 100 degC.
author_names: Masakazu Mukaida

Kazuhiro Kirihara

Shohei Horike

Qingshuo Wei
title: Stable organic thermoelectric devices for self powered sensor applications
year: 2020

abstract: Abstract Organic semiconductors have traditionally been studied for applications related to light emission (LEDs) light absorption (solar cells) and logic (transistors) As of recent years, there has been an additional interest in thermoelectric applications, which goes hand in hand with an increased interest in doping these materials as thermoelectric applications require highly conductive active materials. At the date of writing, the (sub)field of organic thermoelectrics is still in rapid development and has not yet converged on a (set of) quantitative and physics based pictures in which electrical and thermal conductivity and thermopower of doped organic semiconductors can be understood. Such models would be needed to arrive at design rules for optimal performance that have predictive power. At the same time, clear trends are visible in the field. The purpose of this chapter is first to provide an overview of recent experimental results, focusing not on (record) numbers but rather on generic trends. In the second, larger part of this chapter, a critical review of currently available interpretational frameworks is given, and the predictions of these models are compared to the experimental results. The chapter ends with a short outlook.
author_names: Dorothea Scheunemann

Martijn Kemerink
title: Thermoelectric properties of doped organic semiconductors
year: 2021