Single-Crystal Pentacene Valence-Band Dispersion and Its Temperature Dependence

Area of Science:

• Solid-state physics
• Materials science
• Organic electronics

Background:

• The highest occupied molecular orbital (HOMO) and derived valence bands govern hole transport in organic semiconductors.
• Understanding these electronic structures is crucial for developing advanced organic electronic devices.

Purpose of the Study:

• To investigate the valence-band structures of single-crystal pentacene.
• To determine the temperature dependence of energy-momentum dispersion relations for holes.
• To evaluate key charge transport parameters like transfer integrals and effective mass.

Main Methods:

• Utilizing angle-resolved ultraviolet photoelectron spectroscopy (ARUPS) to probe electronic band structures.
• Analyzing the energy-momentum dispersion of valence bands in single-crystal pentacene.
• Measuring ARUPS spectra at various temperatures to observe thermal effects.

Main Results:

• Successfully mapped the valence-band structures of single-crystal pentacene.
• Quantified the intermolecular transfer integral at 43.1 meV and hole effective mass at 3.43 m_e at room temperature.
• Observed a ~20% enhancement in transfer integral and a reduction in hole effective mass upon cooling to 110 K.

Conclusions:

• The study provides detailed insights into hole transport mechanisms in pentacene.
• Temperature significantly influences charge carrier dynamics, affecting transfer integrals and effective mass.
• These findings are vital for optimizing organic semiconductor performance in electronic applications.