Suchergebnisse

Thermoelectrics have emerged as a strategy for solar‐to‐electricity conversion, as they can complement photovoltaic devices as IR harvesters or operate as stand‐alone systems often under strong light and heat concentration. Inspired by the recent success of inorganic‐based solar thermoelectric generators (STEGs), in this manuscript, the potential of benchmark organic thermoelectric materials for solar harvesting is evaluated. It is shown that the inherent properties of organic semiconductors allow the possibility of fabricating organic STEGs (SOTEGs) of extraordinary simplicity. The broadband light absorption exhibited by most organic thermoelectrics combined with their low thermal conductivities results in a significant temperature rise upon illumination as seen by IR thermography. Under 2 sun illumination, a temperature difference of 50 K establishes between the illuminated and the non‐illuminated sides of a poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) film, and ≈40 K for a carbon nanotube/cellulose composite. Moreover, when using light as a heat source, the Seebeck coefficient remains unaffected, while a small photoconductivity effect is observed in PEDOT:PSS and carbon nanotubes. Then, the effect of several geometrical factors on the power output of a solar organic thermoelectric generator is investigated, enabling us to propose simple SOTEG geometries that capitalize on the planar geometry typical of solution‐processable materials. Finally, a proof‐of‐concept SOTEG is demonstrated, generating 180 nW under 2 suns. ; The authors acknowledge financial support from the Spanish Ministry of Economy, Industry, and Competitiveness through the ''Severo Ochoa'' Program for Centers of Excellence in R&D (SEV‐2015‐0496), MAT2015‐70850‐P and PGC2018‐095411‐B‐I00 projects; from the Generalitat de Catalunya through grants 2017SGR488 and AGAUR 2018 PROD 00191; from CSIC through project 201560I032; and from the European Research Council (ERC) under grant agreement no. 648901. This project has received funding from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska‐Curie grant agreement No. 713673. J.P.J. has received financial support through the "la Caixa" INPhINIT Fellowship Grant for Doctoral studies at Spanish Research Centers of Excellence (Grant code: LCF/BQ/IN17/11620035), "la Caixa" Banking Foundation (ID100010434), Barcelona, Spain. O.Z.A. acknowledges CONACYT‐SENER for his Ph.D. scholarship (No 472571). The authors thank Dr. Deyaa Abol‐Fotouh (ICMAB) for the CNT:cellulose sample preparation. The authors thank Dr. Anna Laromaine (ICMAB), Dr. Sebastian Reparaz (ICMAB), and Dr. Carlos Prieto (ICMM) for fruitful discussions. The authors also thank Mr. Martí Gibert Roca for his help with the 3D printer and Dr. Alexander Stangl for his help with the nanovoltmeter. ; Peer reviewed

A combinatorial study of the effect of in-mixing of various guests on the thermoelectric properties of the host workhorse polymer poly[2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene] (PBTTT) is presented. Specifically, the composition and thickness for doped films of PBTTT blended with different polymers are varied. Some blends at guest weight fractions around 10–15% exhibit up to a fivefold increase in power factor compared to the reference material, leading to zT values around 0.1. Spectroscopic analysis of the charge-transfer species, structural characterization using grazing-incidence wide-angle X-ray scattering, differential scanning calorimetry, Raman, and atomic force microscopy, and Monte Carlo simulations are employed to determine that the key to improved performance is for the guest to promote long-range electrical connectivity and low disorder, together with similar highest occupied molecular orbital levels for both materials in order to ensure electronic connectivity are combined. ; The authors acknowledge financial support from the Spanish Ministry of Science and Innovation through the Severo Ochoa" Program for Centers of Excellence in R&D (No. CEX2019-000917-S) and projects PGC2018-095411- B-I00, PGC2018-094620-A-I00, and MAT2017-90024-P (TANGENTS)-EI/Fondo Europeo de Desarrollo Regional and from the European Research Council (ERC) under Grant Agreements Nos. 648901 and 963954. J.M. thanks Ministerio de Ciencia, Innovación y Universidades for the Ramón y Cajal contract. The authors are thankful to Dr. Agustín Mihi for access and support with the FTIR equipment. The authors acknowledge the European funding (European Regional Development Fund and European Social Fund). The authors thank Andrés Gómez Rodríguez from the Scanning Probe Microscopy Laboratory (ICMAB-CSIC) for a set of fine AFM measurements. GIWAXS experiments were performed at NCD-SWEET beamline at ALBA Synchrotron with the collaboration of ALBA staff. Finally, the authors acknowledge the support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unidad de Recursos de Información Científica para la Investigación (URICI). M.K. thanks the Carl Zeiss Foundation for financial support. G.Z. acknowledges the support from Alexander von Humboldt Foundation. ; With funding from the Spanish government through the 'Severo Ochoa Centre of Excellence' accreditation (CEX2019-000917-S). ; Peer reviewed

Doping of organic semiconductors is a powerful tool to optimize the performance of various organic (opto)electronic and bioelectronic devices. Despite recent advances, the low thermal stability of the electronic properties of doped polymers still represents a significant obstacle to implementing these materials into practical applications. Hence, the development of conducting doped polymers with excellent long-term stability at elevated temperatures is highly desirable. Here, we report on the sequential doping of the ladder-type polymer poly-(benzimidazobenzophenanthroline) (BBL) with a benzimidazole-based dopant (i.e., N-DMBI). By combining electrical, UV-vis/infrared, X-ray diffraction, and electron paramagnetic resonance measurements, we quantitatively characterized the conductivity, Seebeck coefficient, spin density, and microstructure of the sequentially doped polymer films as a function of the thermal annealing temperature. Importantly, we observed that the electrical conductivity of N-DMBI-doped BBL remains unchanged even after 20 h of heating at 190 degrees C. This finding is remarkable and of particular interest for organic thermoelectrics. ; Funding Agencies|Swedish Research CouncilSwedish Research Council [2016-03979]; AForsk [18-313, 19310]; Olle Engkvists Stiftelse [204-0256]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009 00971]; Finnish Cultural FoundationFinnish Cultural Foundation; Finnish Foundation for Technology Promotion; Knut and Alice Wallenberg FoundationKnut & Alice Wallenberg Foundation; Knut and Alice Wallenberg FoundationKnut & Alice Wallenberg Foundation [Dnr KAW 2014.0041]

A combinatorial study of the effect of in-mixing of various guests on the thermoelectric properties of the host workhorse polymer poly[2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene] (PBTTT) is presented. Specifically, the composition and thickness for doped films of PBTTT blended with different polymers are varied. Some blends at guest weight fractions around 10-15% exhibit up to a fivefold increase in power factor compared to the reference material, leading to zT values around 0.1. Spectroscopic analysis of the charge-transfer species, structural characterization using grazing-incidence wide-angle X-ray scattering, differential scanning calorimetry, Raman, and atomic force microscopy, and Monte Carlo simulations are employed to determine that the key to improved performance is for the guest to promote long-range electrical connectivity and low disorder, together with similar highest occupied molecular orbital levels for both materials in order to ensure electronic connectivity are combined. ; Funding Agencies|Spanish Ministry of Science and InnovationSpanish Government [CEX2019-000917-S, PGC2018-095411- B-I00, PGC2018-094620-A-I00, MAT2017-90024-P]; European Research Council (ERC)European Research Council (ERC)European Commission [648901, 963954]; Ministerio de Ciencia, Innovacion y UniversidadesSpanish Government; European Regional Development FundEuropean Commission; European Social FundEuropean Social Fund (ESF); CSIC Open Access Publication Support Initiative through its Unidad de Recursos de Informacion Cientifica para la Investigacion (URICI); Carl Zeiss Foundation; Alexander von Humboldt FoundationAlexander von Humboldt Foundation

This is the peer reviewed version of the following article: K. Pudzs, A. Vembris, M. Rutkis, S. Woodward, Adv. Electron. Mater. 2017, 1600429, which has been published in final form at http://onlinelibrary.wi.002/aelm.201600429/full This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. ; Thin films of p- and n- type organic semiconductors for thermo-electrical (TE) applications are produced by doping of tetrathiotetracene (TTT). To obtain p-type material TTT is doped with iodine during vacuum deposition of thin films or by post-deposition doping using controlled exposure to iodine vapors. Thermal co-deposition in vacuum of TTT and TCNQ is used to prepare n-type thin films. The attained thin films are characterized by measurements of Seebeck coefficient and electrical conductivity. Seebeck coefficient and conductivity could be varied by altering the doping level. P-type TTT:iodide thin films with a power factor of 0.52 μWm-1K-2, electrical conductivity of 130 S m-1 and Seebeck coefficient of 63 μV K-1 and n-type TCNQ:TTT films with power factor of 0.33 μWm-1K-2, electrical conductivity of 57 S m-1 and Seebeck coefficient of -75 μV K-1 are produced. Engineered deposition of both p- and n-type thermoelectric conducting elements on the same substrate is demonstrated. A proof of concept prototype of planar thin film TE generator based on a single p-n couple from the organic materials is built and its power generation characterized. ; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union's Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART²

The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013) / ERC Grant Agreement n. 339478. Acronym LAYERENG-HYBMAT. | openaire: EC/FP7/339478/EU//LAYERENG-HYBMAT ; The thermoelectric properties of both pristine ZnO and ZnO-organic superlattice thin films deposited on a cotton textile are investigated. The thin films are fabricated by atomic layer deposition/molecular layer deposition, using hydroquinone as the organic precursor for the superlattices. The resulting thin-film coatings are crystalline, in particular when deposited on a textile substrate with a thin predeposited Al2O3 seed layer. The thermoelectric properties of the ZnO and ZnO-organic superlattice coatings are comparable to those for thin films deposited on conventional inorganic substrates; Al doping can be employed to further improve the thermoelectric properties. The ZnO-organic superlattice thin films moreover show enhanced resistance to mechanical strain. Due to the higher flexibility and lower thermal conductivity in comparison to pristine ZnO thin films, the ZnO-organic superlattice thin films are a possible material platform for flexible thermoelectrics that can be integrated in textiles and applied in wearable electronics. ; Peer reviewed

This study shows an approach to combine a high electrical conductivity of one composite layer with a high Seebeck coefficient of another composite layer in a double-layer composite, resulting in high thermoelectric power factor. Flexible double-layer-composites, made from Bi2Te3-based-alloy/polylactic acid (BTBA/PLA) composites and Ag/PLA composites, are synthesized by solution additive manufacturing. With the increase in Ag volume-ratio from 26.3% to 41.7% in Ag/PLA layers, the conductivity of the double-layer composites increases from 12 S cm(-1)to 1170 S cm(-1), while the Seebeck coefficient remains approximate to 80 mu V K(-1)at 300 K. With further increase in volume ratio of Ag until 45.6% in Ag/PLA composite layer, the electrical conductivity of the double-layer composites increases to 1710 S cm(-1), however, with a slight decrease of the Seebeck coefficient to 64 mu V K-1. The electrical conductivity and Seebeck coefficient vary only to a limited extent with the temperature. The high Seebeck coefficient is due to scattering of low energy charge carriers across compositionally graded interfaces. A power factor of 875 mu W m(-1) K(-2)is achieved at 360 K for 41.7 vol.% Ag in the Ag/PLA layers. Solution additive manufacturing can directly print this double-layer composite into intricate geometries, making this process is promising for large-scale fabrication of thermoelectric composites. ; Funding Agencies|Shanghai Innovation Action Plan Project [17090503600]; National Natural Science Foundation of ChinaNational Natural Science Foundation of China [11811530636, 61504081, 61611530550]; Program for Professor of Special Appointment (Young Eastern Scholar Program) at Shanghai Institutions of Higher Learning [QD2015039]; Swedish Research Council (VR)Swedish Research Council [2016-3365]; Swedish Energy AgencySwedish Energy Agency [46519-1]; Knut and Alice Wallenberg Foundation through the Wallenberg Academy Fellows program; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009 00971]

We present a method to dissolve carbon nanotubes that simultaneously allows to prepare n-doped films. These films are composed of thinner bundles of longer tubes when compared to films prepared using surfactants and sonication. Their negative Seebeck coefficient and high electrical conductivity make them good candidates for thermoelectric applications. We investigate their stability in air by aging them at elevated temperatures, showing stabilities over 500 h, which is further improved by the use of crown ethers. Finally, we demonstrate the usefulness of the prepared materials by fabricating an organic thermoelectric generator comprising 40 legs. ; The authors acknowledge financial support from the Spanish Ministry of Science and Innovation through the "Severo Ochoa" Program for Centers of Excellence in R&D (No. CEX2019-000917-S), Nos. PGC2018-095411-B-I00 and MAT2017-90024-P (TANGENTS)-EI/FEDER; from the Generalitat de Catalunya and European Union (FEDER) through AGAUR 2018 PROD 00191; and from the European Research Council (ERC) under Grant Agreement No. 648901. We also thank Professor Alejandro R. Goñi (ICMAB) for fruitful discussions. ; Peer reviewed

Organic-based energy harvesting devices can contribute to a sustainable solution for the transition to renewable energy sources. The concept of ionic thermoelectrics (iTE) has been recently proposed and motivated by the high values of thermo-voltage in electrolytes. So far, most research has focused on developing new electrolytes with high Seebeck coefficient. Despite the major role of the electrode materials in supercapacitors and batteries, the effect of various electrodes on energy harvesting in iTE devices has not been widely studied. In this work, the conducting polymer poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is investigated as the functional electrodes in iTE supercapacitors. Through investigating the thermo-voltage of iTEs of the same electrolyte with varying composition of PEDOT electrodes, it is identified that the different PSS content greatly affects the overall thermo-induced voltage coefficient, S-eff (i.e., effective thermopower). The permselective polyanion in the electrode causes cation concentration differences at the electrode/electrolyte interface and contributes to an interfacial potential drop that is temperature dependent. As a result, the overall thermo-voltage of the device possesses both an interfacial and a bulk contribution. The findings extend the fundamental understanding of iTE effect with functional electrodes, which could lead a new direction to enhance the heat-to-electricity conversion. ; Funding Agencies|Swedish Government Strategic Research Area in Materials Science on Advanced Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [200900971]; Knut and Alice Wallenberg Foundation (Tail of the sun); Swedish Research CouncilSwedish Research CouncilEuropean Commission [2016-05990, 2016-06146, 202005218, 2018-04037]

Coupling thermoelectrics (TE) with photovoltaics (PV) has emerged as an approach to solid-state solar harvesting, directly converting light and infrared heat into electricity. In this work, we compare PV-TE hybrid devices based on organic semiconductors in three different geometries: a reflection geometry, a non-contact transmission geometry, and a contact transmission geometry. The temperature rises of films of common organic thermoelectric materials, including poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), single-walled carbon nanotubes (swCNT), and poly[2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene] (PBTTT), were measured in configurations representative of the proposed geometries. Because organic semiconductors possess broadband light absorption and low thermal conductivities, a significant rise in temperature was observed under illumination for all geometries. We find, however, that the best configuration is, in fact, the transmission contact mode because it sums two effects. Operating under 1 sun illumination, the temperature of a commercial organic PV module increased by ≈30 K, which leads to an enhancement in OPV performance compared to room temperature. After attaching a thermoelectric to the OPV module, losses from convection are reduced, and the OPV module heats up even more, further increasing its efficiency while additionally enabling thermoelectric generation. Finally, we calculate theoretical thermoelectric efficiencies for the materials and their respective power densities. ; The authors acknowledge financial support from the Spanish Ministry Science and Innovation through the "Severo Ochoa" Program for Centers of Excellence in R&D SEV-2015-0496 (FUNMAT) and CEX2019-000917-S (FUNFUTURE), and PGC2018-095411-B-I00 (RAINBOW) projects; from the Generalitat de Catalunya through grants 2017SGR488 and AGAUR 2018 PROD 00191; and from the European Research Council (ERC) under grant agreement no. 648901. This project has received funding from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement no. 713673. J. P. J. has received financial support through the "la Caixa" INPhINIT Fellowship Grant for Doctoral studies at Spanish Research Centers of Excellence (Grant code: LCF/BQ/IN17/11620035), "la Caixa" Banking Foundation (ID100010434), Barcelona, Spain. O. Z. A. acknowledges CONACYT-SENER for his PhD scholarship (no. 472571). J. P. J. acknowledges the departments of Physics, Chemistry and Geology of the Autonomous University of Barcelona (UAB) as coordinators of the PhD programme in Materials Science. The authors thank Dr A. Roig, Dr A. Laromaine and Dr D. Abol-Fotouh (ICMAB-CSIC) for the CNT:cellulose sample preparation and fruitful discussions. The authors thank Dr Aleksandr Perevedentsev for his help with sample preparation, and Mr Pau Molet for his help with the FTIR measurements. We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI). ; Peer reviewed