Physics of photovoltaic processes
This course concerns the main physical phenomena that occur in the active material of a photovoltaic cell: the absorption of light, the charge generation, transport.
The approach is phenomenological even if it makes extensive use of the concepts and basic tools of quantum mechanics, which are anyway briefly introduced. The proposed models are then compared with existing technologies, describing the photovoltaic cells of the first, second and third generation. The goal is to provide the wealth of basic knowledge needed to design new materials for photovoltaics.
Ultimate theoretical limit of a cell and detailed balance
Two level system,
Susceptibility and refractive index.
Molecular absorption. Adibatic approximation, Vibronic linewidth and Franck-Condon principle.
Einstein A and B coefficients. Strickler-Berg relation.
Kasha molecular exciton in aggregates.
Energy transfer (Foerster, Dexter, Frenkel exciton).
Absorption in a crystal (band structure, carrier relaxation,
Wannier-Mott exciton, dimensionality)
Jablonski diagram, internal conversion, vibrational energy redistribution, radiative decay, inter system crossing, phosphorescence. Mono and bi molecular recombination. Vavilov-Kasha rule.
Charge transfer states.
Band to band transition, Onsager, Poole-Frenkel. Donor-Acceptor system.
Hopping in disordered systems.
Experimental techniques to determine mobility.
General characteristics of a PV cell
Polymer solar cells
Dye sensitized solar cells
Inorganic semiconductor cells (Si p-n junction and thin films)
Luminescent solar collectors