III-V multijunction solar cell technology demands high efficiency for its cost effective production. The proposed new combination of GaP/InGaAs/InGaSb triple junction solar cell is designed to convert more incident photons to electricity, executing higher internal quantum efficiency and promoting higher efficiency solar cells. The use of InGaSb (0.54 eV) as a bottom subcell layer empowers the collection of photons deeper in the infrared spectrum. The efficiency of the proposed multijunction solar cell is 23.53% under 1 sun concentration for AM 1.5 Global spectrum. This paper presents the optimization of quantum efficiency and current matching for each subcell layer with the change in thicknesses and doping concentrations. The work also maximizes open circuit voltage obtained from each of the subcell layers. (C) 2016 Elsevier Ltd. All rights reserved.