The effect of sodium doping to CuInSe2 monograin powder properties

The effect of sodium doping to the electrical and photoluminescence properties of CuInSe2 monograin powders was studied. Sodium was added in controlled amounts from 5 × 1016 cm− 3 to 1 × 1020 cm− 3. The photoluminescence spectra of Na-doped stoichiometric CuInSe2 powders had two bands with peak positions at 0.97 and 0.99 eV. The photoluminescence 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 1 × 1019 cm− 3. This material had the highest carrier concentration 2 × 1017 cm− 3. In the case of stoichiometric CuInSe2 (Cu:In:Se = 25.7:25.3:49.0), Na doping at concentrations of 3 × 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 × 1018 cm− 3 resulted in the best open-circuit voltage.