Impact of a binary Ga₂Se₃ precursor on ternary CuGaSe₂ thin-film and solar cell device properties

CuGaSe₂ (CGS) thin-films grown by the three-stage coevaporation process using various Se-fluxes during each growth stage exhibited distinctive properties different from those grown with a constant Se-flux during all three stages. CGS grain size, growth orientation, and the depletion width in solar cell devices were found to depend strongly on the Ga₂Se₃ precursor formed during the first stage, whereas photo-absorption spectra and device parameters were largely determined by the Se-flux used during the second and third stages when the CGS film near-surface region was formed. A certified efficiency exceeding 10 demonstrated for a ternary CGS solar cell is also reported.