The fabrication and performance of InGaAsSb thermophotovoltaic cells are described. The InGaAsSb layers, grown by organometallic vapor‐phase epitaxy in a multi‐wafer reactor, with a 0.53 eV bandgap are lattice‐matched to a GaSb substrate. Growth series with up to thirty 50 mm wafers have been done with good control of material composition and carrier transport properties. With improved materials and metallization and with a modification to the cell edges, fill factors near 70&percent; and a greater than 60&percent; peak external quantum efficiency are obtained. A two order‐of‐magnitude increase in shunt resistance with a consequent 15&percent; improvement in fill factor was achieved with the improved edge structure. Series resistance, about 20 m&OHgr;, is the remaining limitation to cell performance and is closely correlated with fill factor. © 2003 American Institute of Physics