Ligand derived slow growth and passivation of small CsPbX3 nanocrystals with high brightness and stable tunable emitting

Small CsPbBr 3 and CsPbI 3 nanocrystals (NCs) with tunable sizes and high photoluminescence (PL) were prepared by ligand (Dodecylbenzenesulfonic acid (DBSA)) derived slow growth and surface passivation to decrease structure and surface defects. Namely, the powerful binding of sulfonic acid groups with Pb 2+ and the steric hindrance effect of benzene rings are the key for the preparation of small-sized NCs. The minimum size of CsPbBr 3 NCs is approximately 2.28 nm. Meanwhile, the PL peaks of CsPbBr 3 and CsPbI 3 NCs are adjustable from 461 to 516 nm and 660–685 nm, respectively. The treatment of CsPbX 3 NCs by ZnX 2 (X = Br and I) effectively passivated halide vacancies. The PL quantum yields (PLQYs) reach to 93.8 % for blue-emitting CsPbBr 3 NCs and 89.6 % for red-emitting CsPbI 3 NCs. The strong binding of DBSA to Pb ions enabled small NCs to maintain their initial PL intensity of 80 % after storage for 130 days and ultraviolet light irradiation for 140 min. The ZnX 2 (X = Br and I) treatment did not change the structural stability of CsPbX 3 NCs. Finally, CsPbBr 3 and CsPbI 3 NCs were applied to fabricate white light emitting diodes (LEDs). The color coordinates, as defined by the Commission Internationale de l'Eclairage, are positioned at (0.34, 0.33), accompanied by a correlated color temperature measuring 4441 K, which highlights the successful production of warm white LEDs. This result provides an efficient way for creating CsPbBr 3 NCs with blue emitting and CsPbI 3 with red emitting in short wavelength region.