Dark current-voltage characteristic of triple-junction solar cells: Their relation with the efficiency and the influence of passivating treatments

A correlation between the main parameter of a solar cell, the conversion efficiency, and its dark I – V characteristic is investigated. A formula is derived that expresses an increment (decrement) of the efficiency through a decrement (increment) of the current measured at a certain voltage (here at 2.4 V). Relationships are deduced based on which six methods for passivating the sidewalls of triple-junction InGaP/GaAs/Ge heterostructures grown by metal-organic vapor-phase epitaxy are tested to see how they influence the dark I – V characteristic. The influence of different factors, such as post-growth annealing, damaging radiation, etc., on the solar cell efficiency can be estimated by taking the dark I – V characteristic.