Positioning and doping effects on quantum dot multi-junction solar cell performance

The positioning of InAs quantum dot (QD) layers in a triple-junction GaInP/Ga(In)As/Ge solar cell is studied using numerical modeling techniques. An effective medium is used to describe the absorption characteristics and carrier dynamics in each QD layer. The effects of incorporating 110 layers in the emitter, base layers, as well as between these regions of the middle sub-cell are analyzed with current–voltage characteristics and energy band diagrams. The cell with QDs positioned between the emitter and base demonstrated an efficiency of 31% under 1 sun illumination at room temperature. The performance was then increased to 31.3% by optimizing the QD region doping. Copyright © 2014 John Wiley & Sons, Ltd.