Solar cells: Optical and recombination losses

Abstract

In Sect. 4.1 on Optical Losses, we first look at the absorption of light in a semiconductor, distinguishing thereby between semiconductors with direct transition (direct bandgaps), like GaAs, CdTe etc. and semiconductors with indirect transitions (indirect bandgaps) like silicon. Thereafter we introduce various methods for achieving trapping of the light within the semiconductor, such as (a) the introduction of an ARC (antireflection coating layer), (b) texturing of the front and the back surfaces, (c) mirror formation on the back side of the solar cell. In Sect. 4.2 on Recombination, we will introduce the four main types of recombination processes (a) radiative recombination, (b) Shockley-Read-Hall (SRH) recombination, (c) Auger recombination and (d) surface recombination. In Chaps. 5 and 7 we will apply this basic information to design highly efficient solar cells.