CU-IN-GA-SE NANOPARTICLE COLLOIDS AS SPRAY DEPOSITION PRECURSORS FOR CU(IN,GA)SE-2 SOLAR-CELL MATERIALS

The use of nanoparticle colloids for spray deposition of Cu(In,Ga)Se-2 (CIGS) precursor films and subsequent fabrication of CIGS solar cells has been investigated. According to this approach, amorphous Cu-In-Ga -Se nanoparticle colloids were first prepared by reacting a mixture of CuI, InI3, and GaI3 in pyridine with Na2Se in methanol at reduced tem perature. Purified colloid was sprayed onto heated molybdenum-coated s odalime glass substrates to form Cu-In-Ga-Se precursor films. After th ermal processing of the precursor films under a selenium ambient, CIGS solar cells were fabricated. Cu-In-Ga-Se colloids and films were char acterized by inductively coupled plasma atomic emission spectroscopy, thermogravimetric analysis; transmission electron microscopy, x-ray di ffraction, scanning electron microscopy, and Auger electron spectrosco py. Standard current-voltage characterization was performed on the CIG S solar cell devices with the best film exhibiting a solar conversion efficiency of 4.6%.