ABSTRACT
Photovoltaics (PV) is defined as the science and technology of converting light to electricity, the most common form being the utilization of light from the sun. The concept was first demonstrated by French physicist Edmond Becquerel in 1839 via electrochemical studies of AgCl-coated Pt electrodes (Becquerel 1839). It took another 115 years for the demonstration of the first semiconductor solar cell using silicon (Si) to occur by researchers from AT&T Bell Labs (Chapin et al. 1954), with an initial power conversion efficiency of ~6%. In the intervening years there were various photovoltaic developments, the most important related to the use of a solid substance, selenium (Se), as an active layer (Adams and Day 1876) and the use of Se in a crude module (Fritts 1883). However, it was the application of a known semiconductor and the accompanying complete picture of the band structure of such materials (which was developed in the first part of the twentieth century) that enabled rapid developments in the field of PV in the last 50+ years. It has taken 40 to 50 years to develop a detailed understanding of the physics, materials science, optics, and chemistry of PV materials/devices, and the methods to manipulate them, such that record efficiencies close to that of the single-bandgap entitlement could be developed. Reasons for this will be described below and in more detail in subsequent chapters of this book.
