OVERVIEW

The course describes the physical mechanisms underlying the direct conversion of solar radiation into electrical energy through the photovoltaic effect. Students will gain an understanding of the fundamental thermodynamic limits to efficiency, as well as the constraints on material selection and design parameters for high-efficiency devices.

The course also includes a laboratory activity focused on the electro-optical and morphological characterization of commercial solar cells.

AIMS AND CONTENT

LEARNING OUTCOMES

The course, delivered in the second semester, will guide students toward a thorough understanding of the potential of solar energy to meet humankind’s power needs by exploring a diverse portfolio of renewable energy conversion technologies, with a strong emphasis on photovoltaics (PV). First, they will gain insight into the physical basis of light-matter interaction, linking the optical response to the electronic band structure of materials relevant to PV technologies. Subsequently, they will acquire knowledge about solar energy radiation potential and learn how to apply solar radiation databases to assess the performance of a PV plant in a specific location. They will understand the physical foundation of the photovoltaic effect and first-generation PV technologies, which are primarily based on single-junction silicon solar cells and account for 90% of the PV market. They will also explore the physical and material-related constraints that limit PV conversion efficiency, addressing cutting-edge solutions and new materials currently being researched for high-efficiency devices. Finally, the students will gain hands-on laboratory experience conducting the electro-optical characterization of PV cells. During the third semester, students interested in PV may attend the course titled Inorganic Materials: From the Ground to Photovoltaics, where they will delve into the chemistry of inorganic PV materials, with a focus that goes beyond silicon technologies.

AIMS AND LEARNING OUTCOMES

(i) The learning objectives of the course include the acquisition of theoretical knowledge related to: the solar energy resource and the estimation of photovoltaic production potential, evaluated through the use of reference simulation software (PVGIS) available on Open Access platforms; the physical principles of light–matter interaction, linking the optical response to the electronic band structure of materials relevant to photovoltaic technologies; optical absorption processes in semiconductors; the physics of solar cells and semiconductors, with a particular focus on silicon junction-based devices; thermodynamic limits to the efficiency of photovoltaic converters and new concepts and materials for enhancing solar cell performance.

(ii) Students will be able to critically discuss the physical limits of conversion efficiency in both thermal and photovoltaic solar devices, and will be able to describe how efficiency is affected by physical parameters and constituent materials.

(iii) Students will also be able to apply the acquired knowledge to correctly size a photovoltaic system and to estimate solar irradiance and photovoltaic production potential at a specific location, including through the use of open-source simulation tools (PVGIS).

(iv) The course also aims to provide experimental skills related to the electro-optical and morphological characterization of commercial solar cells.

The specific educational activities and competencies (i–iv) are defined for both the “Materials Scientist: Research Specialist” and “Materials Scientist: Technology Specialist” profiles. Activities (iii) and (iv) are particularly suited to the “Technology Specialist” profile.

The course also aims to foster the acquisition of transversal skills such as functional literacy, personal and social competencies, learning-to-learn ability, and project development capacity.

PREREQUISITES

A solid understanding of the fundamental concepts of Solid State Physics is assumed, with particular reference to the behavior of electrons in semiconductors, as well as basic knowledge of General Physics, especially concerning electromagnetism, optics, and radiation-matter interaction.

TEACHING METHODS

The course includes approximately 42 hours of lectures in which the theoretical topics are presented. Additionally, around 8 hours of laboratory activities are planned, during which various solar cells are characterized in terms of their optical response, the morphology and structure of anti-reflective layers, and their electro-optical response under illumination, by measuring I-V curves and quantum efficiency.

The laboratory work is preceded by a preparatory/planning phase carried out either in class with the instructor or within the student group. Students are expected to learn how to manage the limited time available for conducting measurements, analyzing data, and writing the lab report. Each report will be assessed by the instructors after each activity, allowing students to reflect on and improve their level of preparation. This process will support the development of the transversal skills outlined in the LEARNING OBJECTIVES section.

SYLLABUS/CONTENT

1 - Introduction:
Renewable energy sources, global warming, energy policy.

2 - The Solar Energy Resource:
Solar radiation. Blackbody spectrum; effects of the solar and terrestrial atmosphere: absorption by atoms and molecules, and the spectral distribution of solar radiation.

3 - Dielectric Function and Complex Refractive Index of Semiconductors in the Linear Response Regime:
Models for bound electrons. Multiple resonances. Kramers-Kronig relations. Dense dielectrics. Band structure of semiconductors. Fundamental absorption edge in direct-gap semiconductors. Indirect gap: phonon-assisted transitions. Transitions far from the threshold and band-related effects.

4 - Physics of Solar Cells:
Review of semiconductor physics, with particular reference to the course “Metals, Insulators, Semiconductors” offered in the first semester. Electron-hole recombination (radiative and non-radiative). Recombination at grain boundaries, defects, and surfaces. Minority carrier diffusion; carrier lifetimes and diffusion lengths.

5 - Basic Structure of a Silicon Solar Cell:
Review of p-n and p-i-n junction physics and the Shockley equation. The photovoltaic effect, electron-hole separation. I-V characteristics of a solar cell. Monocrystalline and polycrystalline solar cells. Theoretical limits to energy conversion (Shockley–Queisser limit); efficiency and energy gap; spectral response; effects of parasitic resistances and temperature.

6 - New Concepts and Materials to Improve Solar Cell Efficiency:
Reflection losses; concentrated solar cells. Thin-film solar cells. Photon collection enhancement in nanostructured cells. Overview of other semiconductor materials of interest for photovoltaics. Thermodynamic limits to the efficiency of solar thermal converters. Tandem (multi-junction) solar cells (overview).

7 - Laboratory Activities:
Electro-optical and morphological characterization of commercial solar cells.

RECOMMENDED READING/BIBLIOGRAPHY

• “Handbook of Photovoltaic Science and Engineering” Eds. A.Luque and S. Hegedus, Wiley
• “The Physics of Solar cells” by Jenny Nelson (Imperial College, UK) World Scientific Press
•  “Materials Concepts for Solar Cells” by Thomas Dittrich (Imperial College Press) 2nd edition

TEACHERS AND EXAM BOARD

LESSONS

LESSONS START

At the start of the second semester, as indicated in the academic calendar

Class schedule

The timetable for this course is available here: Portale EasyAcademy

EXAMS

EXAM DESCRIPTION

The exam will consist of an oral interview lasting approximately 45 minutes, on a date that can be arranged with the instructors, who must be contacted well in advance.
The oral examination will be conducted in the presence of two faculty members from the examination committee.
During the exam, the student may present one topic of their choice from the course syllabus (approximately one-third of the total exam time), while the remaining time will be dedicated to an in-depth discussion of the other topics covered in the course.

For students with disabilities or specific learning disorders (SLD), please refer to the section "Additional Information."

ASSESSMENT METHODS

During the oral examination, the actual achievement of the expected learning outcomes will be assessed. The evaluation will focus on the level of knowledge acquired on specific topics covered in the course, the degree of understanding of the physical mechanisms that determine the operation and efficiency of a photovoltaic device, and the student’s critical ability in addressing specific cases presented by the teacher.

In addition, the quality of the presentation, the correct use of specialized terminology, and the ability to engage in critical reasoning in relation to the cases proposed by the instructor will also be evaluated.

FURTHER INFORMATION

During the oral exam, the actual achievement of the expected learning outcomes will be assessed. The level of knowledge acquired on the specific topics of the syllabus, the degree of understanding regarding the role of the physical mechanisms that determine the operation and efficiency of a photovoltaic device, and the critical ability to address specific cases posed by the instructor will be evaluated. Additionally, the quality of the presentation, the correct use of specialized terminology, and the critical reasoning skills with respect to the specific cases posed by the instructor will be assessed.

ADDITIONAL INFORMATION
Students with disabilities or specific learning disorders (SLD) are reminded that in order to request accommodations for the exam, they must first upload the relevant certification on the University website at servizionline.unige.it under the “Students” section. The documentation will be verified by the University’s Inclusion Services Sector for students with disabilities and SLD, as indicated on the affiliated website at the following link: SCIENZA E TECNOLOGIA DEI MATERIALI 11430 | Students with disabilities and/or SLD | UniGe | University of Genoa | UniGe Degree Programs.

Subsequently, at least 10 days before the exam date, students must send an email to the instructor with whom they will take the exam, copying both the School’s Disability and SLD Inclusion Coordinator (sergio.didomizio@unige.it) and the above-mentioned Inclusion Services Sector. The email must specify:

• the name of the course

• the date of the exam session

• the student’s surname, first name, and student ID number

• the compensatory tools and dispensatory measures considered functional and requested.

The coordinator will confirm to the instructor that the student is entitled to request accommodations during the exam and that such accommodations must be agreed upon with the instructor. The instructor will respond indicating whether it is possible to use the requested accommodations.

Requests must be sent at least 10 days before the exam date to allow the instructor time to evaluate their content. In particular, if the student intends to use concept maps during the exam (which must be much more concise than those used for study), failure to meet the deadlines will not allow sufficient time to make any necessary adjustments.

For further information regarding the request for services and accommodations, please consult the document: Guidelines for the request of services, compensatory tools and/or dispensatory measures and specific aids.