Laser Annealing of CZTS Absorber Layers: Molecular Ink vs. Nano Ink Comparison

Kesterite Cu<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>ZnSn(S<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf>Se<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1−x</inf>)<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> (CZTSSe) has demonstrated efficiencies of 14.9% through a non-toxic, eco-friendly solution-based method, making it an attractive option for practical applications. This study investigates the effects of diode laser annealing (DLA) on solution-processed CZTS thin films. Samples were prepared by slot die coating of nano particle CZTS suspensions and by molecular ink deposited via spin coating on molybdenum (Mo) foils. A continuous wave (CW) 808 nm diode laser was employed, with precise control over the laser’s beam profile, including power, scan velocity, and ambient conditions enabling fine-tuned control of the annealing process. Annealing was performed at various power levels under an argon atmosphere to examine its influence on the structural and compositional properties of the films. This approach led to an improvement in the crystallinity and grain size of the as-deposited films. A comparative analysis was conducted to assess the differences between diode laser annealing of CZTS films derived from nanoparticle ink and molecular precursors. The results demonstrate that diode laser annealing effectively improves the quality of CZTS films, potentially providing a viable alternative to traditional furnace annealing techniques for thin-film solar cell applications.