Study of Cu2CdGeSe4 monograin powders synthesized by molten salt method for photovoltaic applications

Abstract Cu 2 CdGeSe 4 monograin powders were synthesized by molten salt method for photovoltaic applications. The effects of salt material (CdI 2 and KI), synthesis temperature and time on the structural, morphological, compositional and optoelectronic properties were investigated. Phase analysis by Raman spectroscopy and X-ray diffraction methods showed that the Cu 2 CdGeSe 4 powder crystals synthesized at 500 °C had tetragonal structure and those synthesized at 600 °C and 700 °C had orthorhombic structure. The band gap values determined from external quantum efficiency measurements were 1.27 eV for orthorhombic Cu 2 CdGeSe 4 and 1.14 eV for tetragonal Cu 2 CdGeSe 4 powder crystals. The monograin layer solar cell on the base of orthorhombic Cu 2 CdGeSe 4 powder showed the best conversion efficiency of 4.21% (active area), with an open-circuit voltage of 0.46 V, a short-circuit current density of 23.3 mA/cm 2 and fill factor of 39%.