The demand for spacecraft power has dramatically increased recently. Higher efficiency, multi-junction devices are being developed to satisfy the demand. The multi-junction cells presently being developed and flown do not employ optimized bandgap combinations for ultimate efficiency due to the traditional constraint of maintaining lattice match to available substrates. We are developing a new approach to optimize the bandgap combination and improve the device performance that is based on relaxing the condition of maintaining lattice match to the substrate. We have designed cells based on this approach, fabricated single junction components cells and tested their performance. We will report on our progress toward achieving beginning-of-life AMO multi-junction device conversion efficiencies above 30%.