Light-Emitting Field-Effect Transistors Consisting of Bilayer-Crystal Organic Semiconductors

A novel device structure for organic light‐emitting field‐effect transistors has been developed. The devices comprise bilayer‐crystal organic semiconductors of a p‐type and an n‐type. The pn‐junction can readily be formed by successively laminating two crystals on top of a gate insulator. This structure enables the efficient injection and transport of electrons and holes, leading to their effective recombination. As a result, bright emissions are attained. The devices are operated by AC gate voltages. Gate‐voltage phase‐resolved drain‐current and emission‐intensity measurements enable us to study the relationship between the emissions and carrier transport. The maximum external quantum efficiency reaches 0.045%. A novel organic light‐emitting field‐effect transistors is presented, consisting of bilayer‐crystal organic semiconductors of a p‐type and an n‐type. In the devices, we observe strong emissions with maximum emission intensities that are larger by hundred times than those of single‐layer crystal devices of each type. Emissions come from both of the crystals. The external quantum efficiency of the bilayer devices reaches 0.045%.