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You are here: Home Events Dr. Mario Caironi "Charge Transport in Solution-Processed Polymer Semiconductors"

Dr. Mario Caironi "Charge Transport in Solution-Processed Polymer Semiconductors"

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Center for Nano Science and Technology @PoliMi, Istituto Italiano di Tecnologia, Milano, Italy

What
  • Seminar
When Oct 31, 2018
from 02:15 PM to 03:00 PM
Where Seminarraum A, FMF, Stefan-Meier-Str. 21, Freiburg
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Polymer semiconductors with steadily improved electronic properties are being synthesized, achieving charge mobility in excess of 5 cm2/Vs for electrons and holes. Such performances are sufficient for a large range of applications of printed, light-weight and mechanically robust circuits, in diverse fields such as wearable electronics, smart packaging, and bio-electronics. Yet, charge transport properties in high mobility donor-acceptor polymer films is still under debate. In this presentation I will show the useful information that can be gathered on the nexus between film microstructure and electronic properties, and on the nature of charge carriers thanks to charge modulation spectroscopy (CMS) and microscopy (CMM) [1], techniques which can selectively probe and map carriers at the buried semiconductor-dielectric interface in a working field-effect transistor (FET) [2]. In particular, I will show that CMS, combined with electrical measurements, allows to reveal a neat two-dimensional charge transport regime in molecularly ordered, nanometers thin, Langmuir-Schäfer monolayers of an electron transporting polymer, where charge transport and electro-optical properties do not depend on the number of layers deposited one on top of the other [3]. As another example, I will show how local charge-modulation spectra recorded with a focused probe in different points of a polymer FET channel allow to distinguish genuine charge-induced spectral features from field-dependent spurious effects related to non-optimal charge injection, thus allowing a proper spectral assignment and a correct assessment of the nature of carriers [4]. This allows to safely map the charge distribution of carriers in polymer FETs under different bias conditions, from unipolar to ambipolar accumulation regime. I will conclude with some examples on the use of such techniques in rationalizing transport properties in recent high-mobility systems.

 
[1] C. Sciascia, et al. "Sub-micrometer charge modulation microscopy of a high mobility polymeric n-channel
field-effect transistor" Advanced Materials 23 (2011) 5086
[2] N. Martino, et al. “Mapping Orientational Order of Charge-Probed Domains in a Semiconducting Polymer”
ACS Nano 8 (2014) 5968
[3] V. D’Innocenzo, et al. “Two-dimensional charge transport in molecularly ordered polymer field-effect
transistors” Journal of Materials Chemistry C 4 (2016) 11135-11142
[4] X.-Y. Chin, et al. “Ambipolar charge distribution in donor-acceptor polymer field-effect transistors” J. Mater. Chem. C 5 (2017) 754-762

invited by Dr. Till Biskup

 

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