Effects of a metallic front gate on the temperature-dependent electronic property of pentacene films

• For the metal-capped and uncapped pentacene films, the mobility was researched.
• The mobility was dramatically increased by capping an In (Au) layer.
• The induced strain by capping a metal layer is found.
• The strain may lead to the electron–phonon coupling variation.
• The enhanced mobility is attributed to the weakened electron–phonon coupling.

The effect of a metallic front gate on the temperature-dependent electronic property of pentacene films was investigated in this study. The carrier mobility exhibits strong temperature dependence, implying the dominance of tunneling (hopping) at low (high) temperatures. The room-temperature mobility was drastically increased by capping an In (Au) layer on the pentacene front surface. However, the carrier concentration is not affected. An increase in the phonon energy occurs for In-capped or Au-capped pentacene samples, which corresponds to the abrupt transition to the nonlocal electron–phonon coupling. The enhanced mobility by capping a metal layer is attributed to a change in the electron–phonon coupling.