Temperature-dependent electronic structure of γ-phase CuI: first-principles insights

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid State Chemistry

Background:

• Copper iodide (CuI) is a promising material for next-generation transparent displays.
• Understanding its electronic properties under varying temperatures is crucial for device optimization.

Purpose of the Study:

• To investigate the temperature-dependent electronic structures of the room-temperature phase of CuI (γ-CuI).
• To elucidate the contributions of electron-phonon interaction and thermal expansion to bandgap changes.
• To evaluate the impact of temperature on hole mobility in CuI.

Main Methods:

• Density-functional-theory (DFT)-based calculations.
• Analysis of bandgap renormalization due to electron-phonon (el-ph) coupling and lattice expansion.
• Application of the Drude model to assess temperature-dependent effective masses and hole mobilities.

Main Results:

• The bandgap of CuI widens with increasing temperature, a behavior contrary to most semiconductors.
• Bandgap widening was quantified as 88.3 meV across a temperature range of 0–600 K.
• Calculated hole mobilities, considering phonon scattering, show good agreement with experimental data.

Conclusions:

• The study provides fundamental insights into the temperature effects on CuI's electronic structure.
• Findings offer guidance for enhancing the performance of electronic and thermoelectric devices utilizing CuI.