Charge accumulation and transport in degenerately doped semiconducting polymers with mixed ionic and electronic conductivity
Contribuinte(s) |
Cramer, Tobias Decataldo, Francesco |
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Data(s) |
23/10/2020
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Resumo |
This thesis is part of the fields of Material Physics and Organic Electronics and aims to determine the charge carrier density and mobility in the hydrated conducting polymer–polyelectrolyte blend PEDOT:PSS. This kind of material combines electronic semiconductor functionality with selective ionic transport, biocompatibility and electrochemical stability in water. This advantageous material properties combination makes PEDOT:PSS a unique material to build organic electrochemical transistors (OECTs), which have relevant application as amplifying transducers for bioelectronic signals. In order to measure charge carrier density and mobility, an innovative 4-wire, contact independent characterization technique was introduced, the electrolyte-gated van der Pauw (EgVDP) method, which was combined with electrochemical impedance spectroscopy. The technique was applied to macroscopic thin film samples and micro-structured PEDOT:PSS thin film devices fabricated using photolithography. The EgVDP method revealed to be effective for the measurements of holes’ mobility in hydrated PEDOT:PSS thin films, which resulted to be <μ>=(0.67±0.02) cm^2/(V*s). By comparing this result with 2-point-probe measurements, we found that contact resistance effects led to a mobility overestimation in the latter. Ion accumulation at the drain contact creates a gate-dependent potential barrier and is discussed as a probable reason for the overestimation in 2-point-probe measurements. The measured charge transport properties of PEDOT:PSS were analyzed in the framework of an extended drift-diffusion model. The extended model fits well also to the non-linear response in the transport characterization and results suggest a Gaussian DOS for PEDOT:PSS. The PEDOT:PSS-electrolyte interface capacitance resulted to be voltage-independent, confirming the hypothesis of its morphological origin, related to the separation between the electronic (PEDOT) and ionic (PSS) phases in the blend. |
Formato |
application/pdf |
Identificador |
Bonafè, Filippo (2020) Charge accumulation and transport in degenerately doped semiconducting polymers with mixed ionic and electronic conductivity. [Laurea magistrale], Università di Bologna, Corso di Studio in Physics [LM-DM270] <http://amslaurea.unibo.it/view/cds/CDS9245/> |
Idioma(s) |
en |
Publicador |
Alma Mater Studiorum - Università di Bologna |
Relação |
http://amslaurea.unibo.it/21710/ |
Direitos |
cc_by_nc_sa4 info:eu-repo/semantics/embargoedAccess end:2022-10-03 |
Palavras-Chave | #PEDOT:PSS,Electrolyte-gated van der Pauw's method,Organic electrochemical transistors,Drift-diffusion modelling of organic semiconductors #Physics [LM-DM270] |
Tipo |
PeerReviewed info:eu-repo/semantics/masterThesis |