Strain Balanced Quantum Well Monolithic Tandem Solar Cells

Abstract

The effect of incorporating strain balanced multiquantum 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.

Solar Cells with InGaN/GaN and InP/InGaAsP and InGaP/GaAs Multiple Quantum Wells

“…The external quantum efficiency of the two tandem solar cells devices was characterized as described in [43], their results are shown in Figure 18. Left curves which are from top to bottom in Figure 18 The Shockley injection currents and Shockley-Read-Hall dark currents of two tandem solar cells devices are simulated using drift diffusion model.…”

Epitaxy for Energy Materials

“…There is vast literature on this topic, and the interested reader can refer to Refs [81][82][83][84][85]. Typically, the strain-balance method allows the absorption edge to be decreased by at least 0.1 eV, while maintaining a particular lattice constant and dark I-V characteristics roughly equivalent to a p-i-n bulk cell.…”

Effect of potential barrier height on the carrier transport in InGaAs/GaAsP multi-quantum wells and photoelectric properties of laser diode

“…InGaAs/GaAsP strain-compensated multiple quantum wells (MQWs), which are promising narrow-band gap materials pseudo-latticematched to GaAs, 1 have been widely used in laser diodes, 2 photodetectors, 3 modulators 4 and in other electronic devices, and now attention is also being paid to their applications in solar cells. 5,6 InGaAs/GaAsP MQWs, with a bandgap of 1.2 eV, can be used as an active region in laser devices and middle cell materials of tandem structures in solar cells to achieve good recombination efficiency and current match conditions, since they can be substantially lattice matched to GaAs by adjusting their average lattice constant. In order to avoid strain accumulation in MQWs that induces crystal defects and thus degrades recombination efficiency, strain balancing, using GaAsP as a tensile strain barrier, has been attempted to compensate the InGaAs compressive well.…”