Dr. Ido Hadar

Abstract:

Hybrid halide perovskites are a novel class of semiconductor materials with promising and versatile optoelectronic properties, enabled by their chemically adjustable structures and dimensionality. The diversity in the metal ions, halide anions, and organic spacers enables a wide range of materials with highly tunable properties and variable dimensionalities. These materials are studied for various applications such as solar cells, detectors, and light-emitting diodes. The ability to control and adjust the optical properties for a required application is significant. Thus, an improved understanding of the structure and optical mechanisms is crucial.

Specific low-dimensionality hybrid halide perovskites exhibit white-light emission at room temperature, associated with self-trapped excitons (STE), making them ideal candidates for illumination applications. We study the correlation between structural and chemical motifs of low dimensionality (2D, 1D) halide perovskites and their STE emission. 

Specifically, we have studied how exchanging the halide anions while maintaining the structure affects the STE properties in a unique 1D perovskite structure based on edge-sharing dimers. These structures exhibit strong, broad emission with PLQY of approximately 40%. By changing the halide from I to Br and Cl, we can see the widening of the bandgap, as expected. However, the broad emission shows an anti-correlated behavior, resulting in red-shifted emission for the Cl sample, with a significantly larger stokes shift. We further study how mixing Br and Cl in a single structure affects the broad emission properties and how different synthetic approaches can be utilized for the fabrication of these compounds.