ABSTRACT
This chapter explains the purpose of enabling the reader to become familiar with the challenges facing those engineers and physicists who spend their lives working on processes and materials aimed at reducing the cost and increasing the efficiency of photovoltaic (PV) cells. Most readers will have already had at least an exposure to the theory of operation of the pn junction and the semiconductor diode in an electronics course, so it will be assumed that the reader will at least be familiar with the basic diode equation. Semiconductor materials are characterized as being perfect insulators at absolute zero temperature, with charge carriers being made available for conduction as the temperature of the material is increased. A more complete representation of semiconductor bandgaps must show the relationship between bandgap energy and bandgap momentum. Some semiconducting materials are classified as direct bandgap materials, while others are classified as indirect bandgap materials.
