Organic Emission Layer Research Articles

Organic Light‐Emitting Transistors Containing a Laterally Arranged Heterojunction

AbstractAn approach to produce organic light‐emitting transistors (OLETs) containing a laterally arranged heterojunction structure, which minimizes exciton quenching at the metal electrodes, is described. This device configuration provides an organic light‐emitting diode (OLED) structure where the anode (source) electrode, hole‐transport material (field‐effect material), light‐emitting material, and cathode (drain) electrode are laterally arranged, thus offering a chance to control the electroluminescent intensity by changing the gate bias. Pentacene and tris(8‐quinolinolato)aluminum (Alq3) are employed as the field‐effect and light‐emitting materials, respectively. The laterally arranged heterojunction structures are achieved by successively inclined deposition of the field‐effect and light‐emitting materials. After deposition of pentacene, a narrow gap of about 10–20 nm between the drain electrode and pentacene was obtained, thereby creating an opportunity to fabricate a laterally arranged heterojunction. In the OLETs, unsymmetrical source and drain electrodes, that is, Au and LiF/Al ones, are used to ensure efficient injection of holes and electrons. Visible‐light emission from OLETs is observed under ambient atmosphere. This result is ascribed to efficient carrier injection and transport, formation of a heterojunction, as well as good luminescence from the organic emissive layer. The device structure serves as an excellent model system for OLETs and demonstrates a general concept of adjusting the charge‐carrier injection and transport, as well as the electroluminescent properties, by forming laterally arranged heterojunctions.

Organic Photonic Crystal Band Edge Laser Fabricated by Direct Nanoprinting

A direct nanoprinting technique is used to fabricate a pit arrangement on the surface of an organic amorphous emissive layer. A pit arrangement with a closely packed hexagonal pattern with a 400 nm pitch is successfully fabricated within 60 s. Pit depth is more than 70 nm and depends on press pressure. The fabricated structure is considered to be a photonic crystal band edge laser, and laser oscillation is confirmed by optical excitation. It is also confirmed that the oscillation threshold can be controlled simply by changing the press pressure used in the direct nanoprinting procedure. The results show that the use of the direct nanoprinting technique enables the fabrication of organic nanostructure devices such as photonic crystal band edge lasers with an organic emissive material.

Study on the effect of organic emission layer in the fabrication of see-through organic light emitting diodes

Study on the effect of organic emission layer in the fabrication of see-through organic light emitting diodes