Environmental Engineering Reference
In-Depth Information
Chapter 9
Effects of Defects on Photovoltaic Solar
Cell Characteristics
9.1 Introduction
The photovoltaic market currently consists mainly of Si, CdTe, CIGS,
and III-V compound-based solar panels. There are some issues,
especiallyonvariationsinperformancemeasurements,stability,and
lifetime.Someofthesevariationsandbehaviours,especiallyinthin-
film solar cells, are not well understood at present. This chapter,
therefore, addresses this subject. The experimental attempts made
on this front, with possible explanations to the observed results
and some solutions to reduce these undesirable behaviours, are
presented in this chapter.
The experimental results are interpreted based on the obser-
vation of defect levels present in thin-film solar cells. The recently
revealednewscience[1,2],asdescribedinchapter4,hasshownthe
effect of several defect levels on CdTe-based solar cells. These ideas
have also been extended to CIGS-based solar cells [3] in chapter 5.
Developing the new ideas further, multi-layer graded bandgap solar
cell structures have been proposed [4, 5], and these concepts have
been experimentally tested using the well-researched GaAs/AlGaAs
