The effect of sodium doping to the electrical and photoluminescence properties of CuInSe2 monogram powders was studied. Sodium was added in controlled amounts from 5 x 10(16) cm(-3) to 1 x 10(20) cm(-3). The photoluminescence spectra of Na-doped stoichiometlic CuInSe2 powders had two bands with peak positions at 0.97 and 0.99 eV. The photolurninescence bands showed the shift of peak positions depending on the Na doping level. Peak positions with maximum energy were observed if added sodium concentration was I x 10 19 cm(-3). This material had the highest carrier concentration 2 x 10(17) cm(-3). In the case of stoichiometric CuInSe, (Cu:In:Se=25.7:25.3:49.0), Na doping at concentrations of 3 x 1017 cm(-3) and higher avoided the precipitation of Cu-Se phase. Solar cells output parameters were dependent on the Na doping level. Sodium concentration 3 x 10(18) cm(-3) resulted in the best open-circuit voltage. (C) 2007 Elsevier B.V. All rights reserved.