OVERVIEW

Organic and polymer semiconductors are revolutioning the consummer electronic market. Nowdays, mobile telephones and TV-sets are often equipped with OLED screens while wearable electronics is more and more important. However, the knowledge of materials allowing for this revolution is poor. Aim of this class is to provide a knowledge of chemistry and physics fundamentals, the understanding of material properties and working principles of electronic devices made by organic semiconductors.  

AIMS AND CONTENT

LEARNING OUTCOMES

Basic knowledge of chemical and physical properties of conjugated polymers and organic semiconductors. Use of such materials in organic optoelectronics and photonic devices (sensors, transistor, led and photovoltaic cells)

AIMS AND LEARNING OUTCOMES

At the end of the class, students are expected to understand:

Main differences between the electronic structure of organic and inorganic semiconductors. Main qualitative differences of the electronic structure of isolated and interacting chains. The concept of energy gap, bandwidth, carrier mobility and intermolecular interactions. The meaning of conjugation length. The qualitative role of disorder in polymer semiconductors on the carrier mobility. 

The importance of solubility in pocessing. The qualitative effect of side chains on processability, controlling intermolecular interactions, the supramolecular structure and the electronic structure.

Methods to  make conjugated polymers oriented and the qualitative effect on the optical properties

Main synthetic strategies to prepare conjugated polymers. The role of regioregularity. Tuning of the ionization potential, electron affinity and energy gap.

Fundamentals of spectroscopy and photophysics in organic semiconductors. The vibronic structure in absorption/fluorescenc espectra of organic semiconductors.

Working principlies of  sensors, transistor, led and photovoltaic cells. Material properties requested to improve device performances.

They have to be able to extract simple information on physical and chemical properties from absorption/fluorescence spectra of a conjugated polymer/molecule as described during the class with several examples.

PREREQUISITES

Good knowledge of chemistry and physics of materials.

TEACHING METHODS

Lectures delivered by Power Point presentations (teachnig notes) available to students on AulaWeb since the first lesson. Simple classroom/lab experiments on light-matter interaction.

SYLLABUS/CONTENT

Section 1: electronic states & spectroscopy

Extended p-electron systems both in molecules and polymers. Conjugation length: ionization potential, electron affinity and HOMO-LUMO gap in the series ranging from ethylene to polyene. Electronic states for the polyene: introduction to the Hückel method for the isolated chain and for interacting macromolecules. Dimerization and Peierls distorsion: metal and semiconducting polymers. Conducting conjugated polymers: doping and applications. Charge transport in semiconducting and conducting polymers. Spectroscopy of conjugated systems: electronic transitions, Franck-Condon principle and vibronic transitions, fluorescence quantum efficiency and lifetime, singlet and triplet electronic states, Jablonski diagram and photophysics.

Section 2: Synthesis & material processing

Synthesis of main conjugated polymer families (polyacetylene, polythiophene, poly(p-phenylenevinylene)). Chemical and physical properties of conjugated materials  (solubility, ionization potential, electron affinity) engineering by chemical functionaization. Supramolecolar structure of conjugated polymers and role of aggregation in the solid state. Orientation techniques of conjugated polymers and anisotropy of their optical and electronic properties.

Section 3: Optoelectronic Devices

Working principles of devices made of conjugated molecules and polymers: sensors, devices for non-linear optics, OLED, PLED, OFET, photovoltaic cells and light harvesting based devices, wearable electronics. Role of the supramolecular structure on the main electronic properties of materials and of devices.

For studentes in Industrial Chemistry(Chemical Sciences, a shorter program holds (4 cfu instead of 6 cfu). In particular, they are allowed to skip the details of electronic structure calculations and light-matter interaction 

RECOMMENDED READING/BIBLIOGRAPHY

References & Books

• Lessons notes provided by the teacher (D. Comoretto)
• Selected papers published on international scientific journals.
• M. Pope and C. Swemberg “Electronic processes in organic crystals and polymers”, Oxford Sci Publ. New York 1999. (Chapter 1).
• M. Klessinger and J. Michl “Excited states and photochemistry of organic molecules”, VCH, New York 1995. (selected paragraphs)
• J.B. Birks “Photophysics of Aromatic Molecules”, Wiley monographs in chemical physics, 1970. (selected paragraphs)
• M.C. Petty "Molecular Electronics", Wiley 2007. (selected paragraphs)

TEACHERS AND EXAM BOARD

Exam Board

DAVIDE COMORETTO (President)

PAOLA LOVA

FRANCESCO BUATIER DE MONGEOT (President Substitute)

MARINA ALLOISIO (Substitute)

MAURIZIO CANEPA (Substitute)

LESSONS

LESSONS START

The class schedule is available at https://easyacademy.unige.it/portalestudenti/ .

Class schedule

The timetable for this course is available here: Portale EasyAcademy

EXAMS

EXAM DESCRIPTION

•Oral exam held by two professors, one of them being D. Comoretto.

•The duration of the exam is no shorter than 30 minutes.

•The student discusses an original power-point presentation or written relation on an item related to the class.

•The student selects the item more suitable to his/her aptitudes/needs with the help of the teacher among those reported in the scientific literature and/or provided on aula-web (usually one or two papers).

•The presentation has to be suitable for understanding by students of the same level.

•The student must show to have understood main physical/chemical/technological fundamentals related to the topics and  to use the suitable technical vocabulary (up to 20/30).

•The clarity of presentation (up to 5/30) and ability to answer questions (up 5/30) will be also evaluated.

ASSESSMENT METHODS

•Goal of the exam is to verify the achievement of the class aims.

•If aims are not achieved, the student is invited to make a deeper study and to ask the teacher for additional explanations before repeating the exam.

•In order to guarantee the correspondence between aims and exam topics, the detailed program is uploaded to AulaWeb and described at the beginning of the course.

For students with specific unparities, the assessment method will comply with the UNIGE rules summarized in https://unige.it/disabilita-dsa.

FURTHER INFORMATION

For any other information, students are invited to directly contact the teacher by email (davide.comoretto@unige.it), telephone (0103538736/8744) or visiting him in his office/lab (https://chimica.unige.it/rubrica/104).

Students who have valid certification of physical or learning disabilities on file with the University and who wish to discuss possible accommodations or other circumstances regarding lectures, coursework and exams, should speak both with the instructor and with Professor Sergio Di Domizio (sergio.didomizio@unige.it), the Department’s disability liaison.