(2014) . The concentration of the sulphur precursor was doubled in comparison to this method to increase the uniformity of the QDs due to faster injection. The sulphur precursor was prepared in a glovebox, by adding 80 mg elemental sulphur to 7.5 mL of dried oleylamine in a round-bottom flask and heating it to 100°C for 60 min. The lead precursor was prepared by mixing 5 g of lead chloride (PbCl 2 ) and 15 mL oleylamine and degassing at 120°C for 1 h. Then, under nitrogen, 2.25 mL S-precursor were swiftly injected. After a specific reaction time, depending on the target size of the PbS QDs according to Weidman, Tisdale et al., the reaction was stopped by injection of cold n-hexane (97%, Extra Dry over Molecular Sieve, AcroSeal®, Acros Organics) and placing the flask in an ice bath. The PbS QDs were purified by injecting 5 mL EtOH (99.5%, Extra Dry, absolute, AcroSeal®, Acros Organics) and centrifuging for 10 min at 4000 rpm. The supernatant was discarded, and the precipitate was redissolved in 3 mL n-hexane. This washing cycle was repeated twice more. 3 mL of dried oleic acid were added to the cleaned particle solution. After stirring, 3 mL EtOH were added, followed by centrifugation for 5 min at 4000 rpm to remove excess oleic acid. The supernatant was discarded and the PbS particles were solved in 6 mL n-hexane.