Nowadays, the fields of electronic and opto-electronic devices are basing future applications on organic semiconductors and on the study of thin film morphology made up by those materials, in order to determine and tailor the performances and the efficiency of the devices. In particular, this thesis deals with thin films of PTCDI-C8, a ntype organic semiconductor made up by conjugated molecule which has proven to have potential in organic opto-electronics, such as organic solar cells, and organic electronics, such as organic field effect transistors. In this case, an important parameter that influences the performances and the efficiency of the devices is the charge carrier mobility. In order to better understand how this aspect can be tailored, studies on the thin film morphology are necessary. In the framework of this thesis an upstream study of the PTCDI-C8 thin film morphology evolution with temperature changes will be presented. In particular the focus will be on the evolution of the crystal structure at different temperatures, analyzing the unit cell parameters and their modifications. In the first part an introduction regarding organic semiconductors and PTCDI-C8 will be illustrated. Then an overview of the experimental techniques and methods used to study the thin film crystal structure will be provided: X-ray techniques and organic molecular beam deposition growth method. Afterwards, the experimental results will be discussed. It has been seen that PTCDI-C8 unit cell parameters follow a trend while changing the temperature, and at the temperature of T=200°C a different crystal structure appears from grazing incident X-ray diffraction measurements.
Al giorno d’oggi, i settori dei dispositivi elettronici ed optoelettronici stanno sviluppando applicazioni basate su semiconduttori organici e sullo studio della morfologia dei film sottili di tali materiali al fine di determinare e modulare le prestazioni e l’efficienza dei dispositivi. In particolare, questa tesi si occupa dello studio di film sottili di PTCDI-C8, un semiconduttore organico di tipo n costituito da molecole coniugate che ha dimostrato di avere potenziale applicativo nell’optoelettronica organica, come le celle solari organiche, e nell’elettronica, come i transistor organici ad effetto di campo. In questo caso, un parametro importante che influenza le prestazioni e l’efficienza dei dispositivi è la mobilità dei portatori liberi di carica. Per comprendere meglio come questo aspetto possa essere sviluppato, sono necessari studi sulla morfologia del film sottile. Nel quadro di questa tesi verrà presentato uno studio a monte dell’evoluzione della morfologia di film sottile di PTCDI-C8 al variare della temperatura. In particolare, l’attenzione sarà focalizzata sull’evoluzione della struttura cristallina a diverse temperature, analizzando i parametri della cella unitaria e le loro modifiche. Nella prima parte verrà illustrata un’introduzione relativa ai semiconduttori organici e al PTCDI-C8. In seguito, verrà fornita una panoramica delle tecniche e dei metodi sperimentali utilizzati per studiare la struttura a cristalli del film sottile: tecniche a raggi X e metodo di crescita del film secondo deposito di molecole organiche. Quindi, saranno discussi i risultati sperimentali. Si è visto che i parametri della cella unitaria del film sottile di PTCDI-C8 al variare della temperatura seguono una tendenza, e alla temperatura di T=200°C appare una diversa struttura cristallina osservata attraverso misure di diffrazione con piccoli angoli di incidenza.
Temperature dependent investigation of PTCDI-C8 thin film structure
BOITANO, SUSANNA
2017/2018
Abstract
Nowadays, the fields of electronic and opto-electronic devices are basing future applications on organic semiconductors and on the study of thin film morphology made up by those materials, in order to determine and tailor the performances and the efficiency of the devices. In particular, this thesis deals with thin films of PTCDI-C8, a ntype organic semiconductor made up by conjugated molecule which has proven to have potential in organic opto-electronics, such as organic solar cells, and organic electronics, such as organic field effect transistors. In this case, an important parameter that influences the performances and the efficiency of the devices is the charge carrier mobility. In order to better understand how this aspect can be tailored, studies on the thin film morphology are necessary. In the framework of this thesis an upstream study of the PTCDI-C8 thin film morphology evolution with temperature changes will be presented. In particular the focus will be on the evolution of the crystal structure at different temperatures, analyzing the unit cell parameters and their modifications. In the first part an introduction regarding organic semiconductors and PTCDI-C8 will be illustrated. Then an overview of the experimental techniques and methods used to study the thin film crystal structure will be provided: X-ray techniques and organic molecular beam deposition growth method. Afterwards, the experimental results will be discussed. It has been seen that PTCDI-C8 unit cell parameters follow a trend while changing the temperature, and at the temperature of T=200°C a different crystal structure appears from grazing incident X-ray diffraction measurements.File | Dimensione | Formato | |
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https://hdl.handle.net/10589/141285