Structural, optical and electrical properties of low-temperature deposition Cu(InxGa1−x)Se2 thin films

In this paper, we study the structural, optical and electrical properties of polycrystalline Cu(In, Ga)Se2 (CIGS) thin films fabricated by the three-stage co-evaporation process on glass substrate at low substrate temperature (TSub). The structural, optical and electrical properties of the as-grown CIGS films have been investigated by X-ray diffraction spectra, transmittance and reflectance spectra, scanning electron microscope and temperature dependent Hall Effect measurement. The results reveal that the properties of the CIGS film deposited at low temperature strongly depend on the chemical composition. A CIGS solar cell with competitive conversion efficiency of 13.2% without anti-reflection layer using low-temperature process at TSub of 450 °C has been demonstrated. Our results suggest that the CIGS absorber for high efficiency solar cells via the low TSub process has a relatively narrow compositional ratio compared to the high TSub process.