Polymorphism in Organic Semiconductor Thin Films: A Nanoscale Investigation of Thermal and Interfacial Effects

Date: Friday, 18 October 2024

Time: 10.30 AM

Venue: Institut de Ciència de Materials de Barcelona (ICMAB, CSIC) - Sala d'Actes Carles Miravitlles

Abstract

Organic semiconductor (OSC) thin films based on π-conjugated molecules have garnered significant interest in electronic devices.
In recent years, substantial progress has been made in this field, resulting in a growing market for organic semiconductor electronic products, such as organic light-emitting diodes (OLED) display technology. Although the development of organic field-effect transistors (OFETs) has not progressed as rapidly as OLEDs, OFETs have emerged as a commercially viable technology. However, many fundamental research questions remain unresolved. Carrier mobility is a primary performance indicator for OFETs. It depends on structural details at different length scales, which are not yet fully understood or satisfactorily controlled. One critical issue is polymorphism.

In this thesis, we combined surface characterization techniques such as synchrotron-based grazing incidence wide-angle X-ray scattering (GIWAXS), atomic force microscopy (AFM), and local Kelvin probe force microscopy (KPFM) to provide a systematic and detailed characterization of polymorphism in C8O-BTBT-OC8 and Ph-BTBT-10 thin films, with particular focus on the role of the interface. Based on our findings, we provide recommendations for optimizing and controlling film quality, which are of significant importance for enhancing the performance and reproducibility of organic field-effect transistor (OFET) devices.

Supervisors

Esther Barrena

PhD comitte

President:  Dra. Carmen Munuera, ICMM, Spain

Secretari: Dr. Cristian Rodríguez, ICN2, Spain

Vocal: Dra. Mercedes Linares, Graz University of Technology, Austria

University: Universitat Autònoma de Barcelona (UAB)

PhD Programme: Material Science