A Quantum Well GaAs/In<sub>0.10</sub>GaAs single junction solar cell, with p-i-n structure, has been fabricated by metal-organic
vapor-phase epitaxy (MOVPE). In this letter, we report on the study of a MQW solar cell structure with different
thickness of i-layers and pairs of QWs, which was used to extend the absorption region and reduce recombination
losses. The efficiency of varied design was discussed accompanying the carrier capture, carrier escape and radiative
recombinations in QWs. The optimized design parameters of the solar cell structures were determined. The
GaAs/InGaAs QW solar cell is proposed to extend the long-wavelength absorption, as a candidate for the next-generation
high-efficiency multi-junction solar cell.