Strain Balanced Quantum Well Monolithic Tandem Solar Cells

The effect of incorporating strain balanced multi-quantum well structures in InGaP/GaAs monolithic tandem solar cells is investigated. At present the majority of InGaP/GaAs tandem cells are current limited by the bottom GaAs junction. Incorporation of multi-quantum well structures in the GaAs bottom junction extends the cell absorption to longer wavelengths. This allows current matched dual junction tandem cells to achieve higher efficiencies. InGaP/GaAs tandem cells have been studied by overgrowing different top cells on two similar quantum well structures and compared to a InGaP/GaAs control cell. A current matched top cell is presented and efficiency enhancement of a tandem by a quantum well cell demonstrated experimentally for the first time