The lifetime of minority carriers is of particular interest in solar cells due to its effect on potential cell efficiency. While "lifetime" is frequently described by a single value parameter, it is a quite complex concept and varies according to material quality, doping level, illumination level and the injection of carriers.
There are two primary categories of carrier lifetime:
The decay of excess minority carriers because of recombination.
The average time taken to generate an electron-hole pair in regions where there is a dearth of carriers such as the space charge region.
The simple term lifetime almost always what refers to the recombination lifetime of excess minority carriers.