Facet‐Engineered Rubidium Lead Halide Nanocrystals for Pyro‐Phototronic Broadband Photodetection

Abstract

Abstract Cesium lead halide has been extensively studied as efficient materials for optoelectronic device applications. Beyond Cs(I), the exploration of other inorganic A‐site monovalent cations remains limited, though Rb(I) stands out as a potential alternative whose role in colloidal nanocrystals is largely unexplored. Here, Rb (I) is employed as an effective A‐site cation in forming monoclinic‐phase RbPb 2 Cl 5 , where Pb (II) heptahedrally coordinated. A template‐mediated cation exchange strategy is employed where 0D Rb 4 CdCl 6 used as host nanocrystals. Upon introduction of Pb (II), fast Cd to Pb ion exchange triggers and 2D RbPb 2 Cl 5 in rhombic prism, hexagonal prism or hexagonal platelet‐shaped nanocrystals are formed depending on the reaction conditions. Further to explore the optoelectronic properties, photo response measurements are carried out which exhibit significant pyro‐photocurrent response from these nanocrystals even under ultra‐low‐intensity light illumination (7 nW cm −2 ) across ultraviolet (UV) to near‐infrared (NIR) spectral range. Despite its centrosymmetric structure, RbPb 2 Cl 5 generates pyro‐photocurrent due to surface halide deficiencies, supported by DFT which shows surface polarization of |𝝙P| = 0.173 C m −2 . These findings highlight the pivotal role of Rb (I) in stabilizing these nanostructures and open a new avenue for their application in advanced optoelectronic devices.