Modulated photocurrent measurements in double junction solar cells

Frequency dependent external quantum efficiency (EQE) measurements were performed on double junction solar cells by a custom-designed system consisting of an array of various monochromatic LEDs. LEDs were operated both at constant intensity and pulsed at various frequencies to explore the frequency response of each junction under various conditions. An equivalent circuit model, incorporating the effects of shunt resistances, junction capacitances, optical light coupling and the series resistance was then used to explain the various features and findings obtained from these measurements.