Ligand-Assisted Breaking Crystal Symmetry to Achieve Stable γ-CsPbI₃ Nanorods with Strong Polarization Response

Abstract

Generally, the properties of CsPbX3 (X = Cl, Br, I) are closely related to their morphology, size, composition and phase. Black phase (α, β, or γ) CsPbI3 easily transforms to yellow phase (δ) CsPbI3 accompanied by optical performance decay at room temperature. A temperature-dependent phase transition is a routine process for bulk CsPbI3, whereas there is a lack of an effective method to control the phase of CsPbI3 nanocrystals. It is still interesting and challenging to control the morphology and phase transition of black phase CsPbI3. Herein, we proposed a ligand-assisted strategy of breaking crystal symmetry via a short Pb–F bond to simultaneously achieve a phase transition and an nisotropic morphology. High-quality γ-CsPbI3 nanorods (NRs) could be obtained due to F– preferential adsorption on the γ-CsPbI3 (220) crystal plane to inhibit its growth and allow preferential growth orientation perpendicular to the γ-CsPbI3 (202) crystal plane. Benefiting from Pb–F bond passivation and the hydrophobic phenyl group of ligands, γ-CsPbI3 NRs exhibited good water resistance and crystal phase stability. Furthermore, a high-quality γ-CsPbI3 NR film was assembled with a strong emission anisotropy polarization degree of up to 0.63 and the demo experiment of polarization imaging confirmed that the γ-CsPbI3 NR film could meet the needs of practical applications.

Dual‐Site Passivation for Bright and Stable Blue‐emitting CsPbBr3 Nanoplatelets

“…Colloidal perovskite nanocrystals (NCs) have potential to be the next generation of full-color-gamut displays owing to their DOI: 10.1002/lpor.202301027 outstanding semiconducting properties. [1][2][3][4][5] Particularly, noteworthy is their capacity to achieve the three primary colors of red, green, and blue through the chemical tuning of halogen anion in perovskite analogs. However, lattice mismatches and deep defect level, as well as phase separation induced by halogen ions drift in Br─Cl mixed perovskites dramatically suppress the radiative recombination, thereby resulting in the poor efficiency of blue perovskite lightemitting diodes (PeLEDs).…”

Stable deep-blue FAPbBr3 quantum dots facilitated by amorphous metal halide matrices

“…15 Although ligands having strong affinity, functional groups can passivate vacancies and reduce ligand shedding, the dynamic adsorption and desorption process of ligands is a key factor to degrade the optoelectronic properties of LHP in the long term. 16–20 According to the properties of common quantum dots (QDs), the core–shell structure can stabilize the core from both chemical and physical factors. 21 Whereas, such a compact core–shell structure can hardly be achieved for LHP due to the incompatibility of the ionic LHP core and covalent shell (ZnS, PbS, etc.…”

Multidentate Ligand-Passivated CsPbI3 Perovskite Nanocrystals for Stable and Efficient Red-Light-Emitting Diodes

“…CsPbI 3 nanocrystals (NCs) have become the research hot spot in the field of light-emitting diodes (LEDs) due to their excellent optoelectronic properties such as high photoluminescence quantum yields (PLQY), high color saturation, and high defect tolerance. − Generally, CsPbI 3 NCs are usually synthesized by the hot-injection method with ligands of oleic acid (OA) and oleylamine (OLA). − Whereas, such ligands limit the promotion of their wide applications. (1) OA and OLA are weakly bonding to the CsPbI 3 NCs surface.…”