Back to Search
Start Over
Seebeck Effects in N-Type and P-Type Polymers Driven Simultaneously by Surface Polarization and Entropy Differences Based on Conductor/Polymer/Conductor Thin-Film Devices
- Source :
- ACS Nano. 9:5208-5213
- Publication Year :
- 2015
- Publisher :
- American Chemical Society (ACS), 2015.
-
Abstract
- This paper reports Seebeck effects driven by both surface polarization difference and entropy difference by using photoinduced intramolecular charge-transfer states in n-type and p-type conjugated polymers, namely IIDT and IIDDT, respectively, based on vertical conductor/polymer/conductor thin-film devices. We obtain large Seebeck coefficients of -898 μV/K from n-type IIDT and 1300 μV/K from p-type IIDDT when the charge-transfer states are generated by a white light illumination of 100 mW/cm(2), compared with the values of 380 and 470 μV/K in dark condition, respectively. Simultaneously, the electrical conductivities are increased from almost insulating state in dark condition to conducting state under photoexcitation in both n-type IIDT and p-type IIDDT based devices. The large Seebeck effects can be attributed to the following two mechanisms. First, the intramolecular charge-transfer states exhibit strong electron-phonon coupling, which leads to a polarization difference between high and low temperature surfaces. This polarization difference essentially forms a temperature-dependent electric field, functioning as a new driving force additional to entropy difference, to drive the energetic carriers for the development of Seebeck effects under a temperature difference. Second, the intramolecular charge-transfer states generate negative or positive majority carriers (electrons or holes) in the n-type IIDT or p-type IIDDT, ready to be driven between high and low temperature surfaces for developing Seebeck effects. On the basis of coexisted polarization difference and entropy difference, the intramolecular charge-transfer states can largely enhance the Seebeck effects in both n-type IIDT and p-type IIDDT devices. Furthermore, we find that changing electrical conductivity can switch the Seebeck effects between polarization and entropy regimes when the charge-transfer states are generated upon applying photoexcitation. Therefore, using intramolecular charge-transfer states presents an approach to develop thermoelectric effects in organic materials-based vertical conductor/polymer/conductor thin-film devices.
- Subjects :
- chemistry.chemical_classification
Materials science
Condensed matter physics
business.industry
General Engineering
General Physics and Astronomy
Polymer
Conjugated system
Conductor
Photoexcitation
chemistry
Seebeck coefficient
Intramolecular force
White light
Optoelectronics
General Materials Science
Thin film
business
Subjects
Details
- ISSN :
- 1936086X and 19360851
- Volume :
- 9
- Database :
- OpenAIRE
- Journal :
- ACS Nano
- Accession number :
- edsair.doi.dedup.....b2b0c892ef96ff5178882a0744c20159