Photovoltaic Energy Conversion – Fundamentals and Applications

Climate Change and Energy Economy: This part of chapter 1 discusses the world´s energy reserves and annual energy consumption and introduces photovoltaics as an interim solution to the world´s growing demand for electrical energy.

Quantum Statistics: I derive distribution functions for integer spin particles (bosons) and half-integer spin particles (fermions) and discuss their properties with regard to the already known Maxwell-Boltzmann statistics of particles. Then, I introduce Fermi-Dirac (FD) quantum statistics and its application to the physical description of the valence electron gas in metals.

Semiconductors and pn-junctions: We discuss the intrinsic properties of semiconductors, specifically their energy levels (band structure), the density of states and carrier distribution functions, as well as intrinsic carrier concentrations. Then, we discuss the effect of doping on the intrinsic carrier concentration and Fermi levels in semiconductors. Finally, what happens when a semiconductor is exposed to light and how the generation of excess charge carriers in a solar cell leads to the so-called quasi-Fermi level splitting, resulting in work performed by the solar cell.

Radiative recombination and charge transport: We discuss radiative carrier recombination in the framework of the detailed balance principle and the continuity equation, as well as charge carrier transport by drift and diffusion.

Non-radiative recombination: We discuss non-radiative (dark, radiation-less) carrier recombination processes including Shockley-Read-Hall (SRH), surface recombination (SR), and Auger-Meitner recombination (AMR) processes and their impact on photovoltaic device performance.

pn junctions: What happens when you bring together in physical contact an n-type and a p-type semiconductor to create what is called a pn-junction, which is the core of any photovoltaic device.

The efficiency of ideal solar cells: In this final chapter, we discuss the theoretical efficiency limit of the ideal solar cell and compare it with the efficiency of real solar cells.