Amine-Free CsPbBr₃ Perovskite Nanocrystals with a Near-Unity Photoluminescence Quantum Yield for a Superfast Photodetector

Herein, we have prepared halide and mixed-halide all-inorganic perovskite nanocrystals (PNCs) using an amine-free synthetic approach. Generally, monohalo-containing halide sources and their mixture have been used to prepare cesium lead halide and mixed-halide PNCs, respectively. In the current study, we made CsPbBr 3 PNCs using a low concentration of 1,3-dibromopropane compared to other bromide sources in the earlier reports. The optimized sample has shown a near-unity (98.5%) relative photoluminescence quantum yield with ambient stability for over 3 months and excellent thermal stability. Rhomicuboctahedron- and dodecahedron-shaped orthorhombic CsPbBr 3 PNCs were formed with average particle sizes of 25–34 nm. To show the generality of the synthesis method, we have also prepared CsPbCl 3 and CsPb(Cl, Br) 3 PNCs using 1,3-dichloropropane, 1-bromo-3-chloropropane, and 1,2-dibromo-3-chloropropane. The synthesis method offers to tune the halide concentration in the mixed-halide PNCs by properly selecting multihalogen groups containing a single precursor. This amine-free CsPbBr 3 PNC-based photodetector can detect ultraviolet (UV), blue, and green light. It has shown a superfast rise/fall time of 104/35 μs with a responsivity of 3.03 mA/W and a detectivity of 5.55 × 10 9 Jones at 40 mW/cm 2 under the UV light.