Rear-emitter n/p ⁺ cells were investigated as an alternative to conventional n ⁺ /p front-emitter cells for potentially increased tolerance against threading dislocation-induced lifetime degradation. A comparison of MOCVD-grown front- and rearemitter GaAs _0.75 P _0.25 cells for use in III-V/Si tandem solar cells demonstrates that the rear-emitter design has lower dark current and higher V _OC , but lower J _SC . Analysis of the collection dynamics in the rear-emitter cell structure indicates a heightened sensitivity to front-surface and Al _0.66 In _0.33 P/GaAs _0.75 P _0.25 (window/base) interface recombination, which is exacerbated by Fermi level pinning at the window/air interface. This work indicates that the rear-emitter design is a promising alternative to front-emitter structures due to its improved minority carrier lifetime and therefore V _OC , but careful optimization of device structure, and possibly material quality, is necessary to improve the minority carrier collection.