Low-Temperature Solution Growth and Characterization of Halogen (Cl, I)-Doped CsPbBr3 Crystals

The all-inorganic halide perovskite CsPbBr3 exhibited extraordinary photoelectric properties as well as great potential for various optic-electronic devices. The introduction of a Cl/I dopant is an effective method to optimize their properties. However, it is still a challenge to grow doped CsPbBr3 single crystals from solution. In this work, we report on the crystal growth of Cl/I-doped CsPbBr3 crystals using the modified inverse temperature crystallization (ITC) method. The components of raw materials and solvent in precursors were precisely tailored. The resulting doping ratio between the actual content and the nominal content are 0.99 and 0.046 for Cl and I, respectively. It indicates that I ion doped crystals exhibit more severe stoichiometric deviation due to the lower decomposition energy. The crystal structure, morphology, and optical properties of doped crystals were also investigated systematically. The {101} and {010} facets of as-grown crystals were influenced by the doping process. PL and UV transmittance spectra exhibited changes in the band gap in Cl/I-doped crystals. Finally, the phase diagram of basic photoelectric properties was determined for CsPb(Br1–nCln)3 crystals and it reveals conductive type changes from the P type to N type with an increase in the doping content of the Cl element. The optimum component of CsPb(Br0.93Cl0.07)3 demonstrates the highest resistivity of 4.3 × 109 Ω cm, an on/off ratio of ∼40, and a mobility of 414 cm2 V–1 s–1 as well as the lowest carrier concentration of 3.57 × 107 cm–3. Our work provides a strategy to grow doped halide perovskite crystals and tailor their optical and electrical properties.