We proposed single-heterojunction and double-heterojunction cell structures to increase the open-circuit voltage in InGaAs/InP-based solar cells. Compared with a homojunction cell, an open-circuit voltage improvement for the single-heterojunction cell is not observed, but an increase of 30.2% in open-circuit voltage for the double hetero-junction cell is observed. As a result, the efficiency of the double-heterojunction cell is increased by 23.9% that of the homojunction cell.