Charge accumulation and transport in degenerately doped semiconducting polymers with mixed ionic and electronic conductivity


Autoria(s): Bonafè, Filippo
Contribuinte(s)

Cramer, Tobias

Decataldo, Francesco

Data(s)

23/10/2020

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

http://amslaurea.unibo.it/21710/1/Charge%20accumulation%20and%20transport%20in%20degenerately%20doped%20semiconducting%20polymers%20with%20mixed%20ionic%20and%20electronic%20conductivity.pdf

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