Synthesis of CuIn_xGa_1−xSe₂ nanoparticles in organic solvent for thin film solar cells

Chalcopyrite CuIn_1−xGa_xSe₂ (CIGS; x < 0.3) nanoparticles were synthesized by reacting CuCl, InCl₃, GaCl₃ and Se in oleyl amine over 250 °C. Depending on the reaction temperature and duration, the obtained nanoparticles had sizes of less than 100 nm and different chemical compositions. Because the atomic percentage of Se decreased with increasing reaction time, the proportion of Se and Ga content also changed. Furthermore, the lattice parameters, a and c, changed with increasing reaction temperature and time. Lastly, the bandgap energies of the CIGS films coated on glass plates were ∼ 0.98 eV and did not significantly change with increasing heat-treatment temperature. - Highlights: • CuIn_1−xGa_xSe₂ (x < 0.3) nanoparticles synthesized by solution process in oleyl amine. • Se an Ga content in chalcopyrite particles increased with reaction time. • The nanoparticle lattice parameters changed with reaction temperature and time. • Band gaps remained fairly stable upon change of reaction temperature and time