(a) AFM image with (b) height profile of the printed 2D GaS layer confirming bilayer deposition. The profile is offset to the substrate’s surface. (c,d) Confocal PL map shows a patterned area made of 2D GaS (green) on a SiO2/Si substrate (black), demonstrating that a near-uniform 2D layer is obtained in a large area along with the PL spectra from areas noted on map (c, patterns 1 and 2). Due to the excitation wavelength limitation of confocal PL, the deep trap emission is used for assessing the uniformity of the PL pattern. (e) PL emission spectra demonstrating contributions of the interband transitions (red) and deep trap recombinations (black). The deep trap emission spectrum is scaled by a factor of 10 for clarity. (f) High-resolution transmission electron microcsopy (HRTEM) of a flake mechanically scratched from the printed GaS film. Additional HRTEM images are presented in Supplementary Fig. 5. A full discussion on continuity of the 2D films, grain boundaries and the concentration and nature of defects are presented in the Supplementary Information (Supplementary Figs 1c,d, 5 and 6).