Microscale Thermal Inhomogeneity Enabled Bandgap Engineering in Perovskite Nanowire Arrays

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Physics

Background:

• Thermal transport is typically viewed as rapid and random at the microscopic level.
• Perovskite nanowires (NWs) are promising materials for optoelectronic applications.

Purpose of the Study:

• To investigate and report the formation of microscale thermal inhomogeneity in single halide perovskite nanowires (NWs).
• To demonstrate the conversion of temperature gradients into compositional gradients for bandgap engineering.
• To explore the application of these gradient NWs in miniaturized optoelectronic devices.

Main Methods:

• Fabrication of composition-graded NWs using anion-exchange with halogen-containing vapor.
• Employing heat sources/sinks to induce thermal gradients.
• Quantitative analysis using spatial-resolved scanning probe characterizations.
• Thermal simulations to determine temperature gradients.

Main Results:

• Significant microscale thermal inhomogeneity was observed in perovskite NWs.
• A prominent temperature gradient of up to 3.6 °C µm⁻¹ was revealed along the NWs.
• The thermal inhomogeneity is attributed to the ultra-low thermal conductivity of perovskites and reduced NW diameter.
• Composition-graded NWs with excellent optoelectronic features were successfully fabricated.

Conclusions:

• Microscale thermal inhomogeneity in perovskite NWs can be leveraged for compositional grading via bandgap engineering.
• This approach provides guidelines for manipulating perovskite composition through phononic engineering.
• Gradient NWs hold potential for ultracompact microspectrometers, spectral imaging sensors, and other miniaturized optoelectronic devices.