Improved bandgap-voltage offset in InGaAs/InAlGaAs quantum well solar cells

In recent years, the implementation of bandgap engineering techniques for solar energy conversion has been demonstrated with exciting results, using both quantum wells (QWs) and quantum dots. Here, the exploitation of a fully lattice-matched QW / barrier system is introduced as an attractive new possibility for this type of device. Photovoltaic characterization is performed and relevant solar cell parameters are reported. For these devices, sixteen layers of 5 nm InGaAs QWs / 10 nm InAlGaAs barriers were embedded into the i-region of a 1.0 eV InAlGaAs solar cell, and the results compared to a 1.0 eV InAlGaAs control solar cell. One-sun J_sc is enhanced in the QW cell by 5.3% compared to that of the InAlGaAs control device, while the open circuit voltage is reduced by 153 mV compared to the control. External quantum efficiency measurements reveal a 1.6 mA/cm² gain from the QW absorption region.