Disorder is found to drastically affect the electronic bandgap, while avoiding the detrimental presence of localised states. By controlling the crystal annealing temperature as well as the subsequent crystal cooling rate, the disorder and thus bandgap energies of this and potentially other A 2 BCh 2 X 3 materials could be finely tuned, allowing the targeted application of these emerging earth-abundant absorber materials in single-junction or tandem solar cells.