Redistributed Current Density in Lateral Organic Light-emitting Transistors Enabling Uniform Area Emission with Good Stability and Arbitrary Tunability.

Organic light-emitting transistors (OLETs), integrating the functions of an organic field-effect transistor (OFET) and an organic light-emitting diode (OLED) in a single device, have unique advantages to meet the miniaturization and integration trend for the next-generation display technology. However, the great challenge of achieving uniform area emission in OLETs, especially in lateral OLETs that with good planar integration significantly hinders their development in this field. Herein, we propose an effective solution to obtain well-defined area emission in lateral OLETs in which a charge transport buffer (CTB) layer is introduced between the conducting channel and emitting layer beneath the drain electrode. Comprehensive theoretical simulation and experimental results demonstrate that the potential beneath the drain electrode is well-redistributed, which is mainly attributed to the shielding effect of the CBT-layer on the equipotential drain electrode. As a result, a highly uniform current density under the drain electrode was observed. In this case, uniform recombination of balanced holes and electrons can be guaranteed, which is essential for the formation of area emission in the following OLETs. Furthermore, well-defined uniform RGB area emission OLETs were constructed by incorporating 2,7-dioctyl[1] benzothieno[3,2-b][1]benzo-thiophene (C8 -BTBT) as the conducting layer, 1,1-bis[(di-4-tolamino)phenyl]cyclohexane (TAPC) as CTB-layer and three phosphorescent materials as the emitting layer. These RGB area-emission OLETs demonstrate good gate tunable ability (ON/OFF ratio 106 ), high loop stability (over 200 cycles) as well as high aperture ratio (over 80%) due to the arbitrary tunability of device geometry. This work provides a new avenue for constructing area-emission lateral OLETs, which have great potential for display technology because of their good compatibility with conventional fabrication techniques. This article is protected by copyright. All rights reserved.