Facet-Engineered Rubidium Lead Halide Nanocrystals for Pyro-Phototronic Broadband Photodetection.

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• Cesium lead halides are well-studied optoelectronic materials.
• Exploration of other monovalent cations like Rubidium (I) in colloidal nanocrystals is limited.
• Rubidium (I) presents a potential alternative for novel optoelectronic applications.

Purpose of the Study:

• To investigate the role of Rubidium (I) as an A-site cation in colloidal nanocrystals.
• To synthesize and characterize monoclinic-phase RbPb2Cl5 nanocrystals.
• To explore the optoelectronic properties, specifically the pyro-photocurrent response, of these novel materials.

Main Methods:

• Template-mediated cation exchange using 0D Rb4CdCl6 host nanocrystals.
• Introduction of Lead (II) to induce Cd to Pb ion exchange.
• Formation of 2D RbPb2Cl5 nanocrystals with varying morphologies (rhombic prism, hexagonal prism, hexagonal platelet) based on reaction conditions.
• Photo response measurements to assess optoelectronic properties.
• Density Functional Theory (DFT) calculations to investigate surface polarization.

Main Results:

• Successful formation of monoclinic-phase RbPb2Cl5 nanocrystals.
• Synthesis of 2D RbPb2Cl5 nanocrystals with diverse morphologies.
• Observation of significant pyro-photocurrent response across UV to NIR spectral range, even under ultra-low light intensity (7 nW cm⁻²).
• DFT calculations confirmed surface polarization (|ΔP| = 0.173 C m⁻²) as the origin of pyro-photocurrent in the centrosymmetric structure due to surface halide deficiencies.

Conclusions:

• Rubidium (I) plays a crucial role in stabilizing RbPb2Cl5 nanostructures.
• The synthesized RbPb2Cl5 nanocrystals exhibit promising pyro-photocurrent properties for optoelectronic applications.
• This work opens new avenues for utilizing Rb-based inorganic materials in advanced optoelectronic devices.