Isolation and Purification of CsPbBr2Cl Nanocrystals. CsPbBr2Cl NCs were collected by centrifuging the suspension (7000 rpm, 10 min), decanting the supernatant, and collecting the precipitate. The precipitate was centrifuged again without addition of a solvent (7000 rpm, 5 min), and the resulting supernatant was removed with a syringe, to separate the traces of residual supernatant. The precipitate was dissolved in 2 mL hexane and centrifuged again (2500 rpm, 5 min) to remove aggregates and larger particles. The resulting supernatant was filtered through a 0.2 µm PTFE syringe filter and stored as stock solution inside of a glovebox with a typically concentration of 10 mg/mL.