• 091582 - FUNCTIONAL MATERIALS

Objectives:

The course aims at providing knowledge about organic materials for electronics and optoelectronics. The course deals with conducting materials, photochromic materials, liquid crystals, as distinct topics. For each class of materials, molecular structure-properties relationships are studied also considering the possible technological applications. Attention is focused on the design of devices such as LEDs, transistors, photovoltaic cells, LCDs, sensors and smart windows. Finally, techniques for the deposition of the organic materials into films are considered.

The expected learning outcomes are:

• knowledge of the principles of molecular engineering of electronic materials, i.e. organic semiconductors, and optically-active materials
• ability to apply the principles of molecular engineering to design functional materials for specific applications
• knowledge of the working principles of the main electronic devices, their characteristics, components and architecture.
• Ability to apply the above knowledge to a critical description and discussion of the devices and related materials properties, limitations and developments.

These learning outcomes are expected to provide the student basic knowledge tools necessary to i) understand the technology trends and i) perform future activities aimed at the development of materials for electronics optoelectronics and smart optics.

Functional materials: basic principles. Molecular machines: an example of smart molecules.

Fundamentals on organic functional materials: molecular skeleton, side groups; the electronic effect of side groups.

Conjugated materials

- Molecular design: from localized chemical bonding to delocalized chemical bonding (LCAO, the frontier energy levels)

- Structure to properties relationship: the UV-vis spectroscopy

- Polyacetylene: structure, synthesis, electrical properties; Shirakawa films

- Doping: chemical and electrochemical processes; charge carriers in organic materials; fundamentals of charge transport

- The deactivation from the excited state: the emissive properties (photoluminescence)

- Applications of conducting polymers: OLED, photovoltaic cells, thin film transistors, smart windows, sensors

Liquid crystals

- Fundamentals, mesogens, main LC phases; polymer liquid crystals; LC embedded in polymer matrix (preparation methods, drop configuration, smart windows).

- Liquid crystal displays.

Photochromic and thermochromic materials

- Fundamentals, main families

- Applications: ophthalmic lenses, inks

If possible, and if permitted by the schedule of lectures, at the end of the course a lecture from an external speaker will be organized.

See bibliography for suggested books (covering more than the programme of the course). Additional material or lecture notes are given by the lecturer. 

Although not strictly necessary, a basic background in organic chemistry is useful to understand the molecular design of functional materials.

A written examination, which consists in:

• A numerical exercise on OFETs, photovoltaic cells or OLEDs
• An open question of one of the main topics of the course
• An exercise on the structure-to-property relationship
• A series of multiple choice questions

In the open question, the student is required to clearly describe and critically discuss the proposed topic. Not only the knowledge about the topic is assessed, but also the correct use of a proper scientific language and clarity in the description. As for the numerical exercise, one type of device (i.e. FET, photovoltaic cell, LED) is proposed and the main characteristics have to be calculated starting from the given experimental data. Regarding this part, not only the correct calculation is assessed but also the proper use of significant decimals and units of measurement. Then, starting from the knowledge acquired during the course the efficiency of the device has to be assigned to a proper material (or to a specific material processing or post processing) and the assignment has to be properly supported. The structure-to-property exercise aims at evaluating the ability of the student to apply the acquired knowledge on molecular design to a case study, finding the right key to solve the problem.