Synthesis of Cu-Poor copper-indium-gallium-diselenide nanoparticles by solvothermal route for solar cell applications

Abstract

Copper-indium-gallium-diselenide (CIGS) thin films were fabricated using precursor nanoparticle ink and sintering technology. The precursor was a Cu-poor quaternary compound with constituent ratios of C u / (I n + G a) = 0.603, G a / (I n + G a) = 0.674, and S e / (C u + I n + G a) = 1.036. Cu-poor CIGS nanoparticles of chalcopyrite for solar cells were successfully synthesized using a relatively simple and convenient elemental solvothermal route. After a fixed reaction time of 36 h at 180°C, CIGS nanocrystals with diameters in the range of 20-70 nm were observed. The nanoparticle ink was fabricated by mixing CIGS nanoparticles, a solvent, and an organic polymer. Analytical results reveal that the Cu-poor CIGS absorption layer prepared from a nanoparticle-ink polymer by sintering has a chalcopyrite structure and a favorable composition. For this kind of sample, its mole ratio of Cu: In: Ga: Se is equal to 0.617: 0.410: 0.510: 2.464 and related ratios of G a / (I n + G a) and C u / (I n + G a) are 0.554 and 0.671, respectively. Under the condition of standard air mass 1.5 global illumination, the conversion efficiency of the solar cell fabricated by this kind of sample is 4.05%. © 2014 Chung Ping Liu et al.