Redistributed Current Density in Lateral Organic Light‐Emitting Transistors Enabling Uniform Area Emission with Good Stability and Arbitrary Tunability

Abstract Organic light‐emitting transistors (OLETs), integrating the functions of an organic field‐effect transistor (OFET) and organic light‐emitting diode (OLED) in a single device, are promising for the next‐generation display technology. However, the great challenge of achieving uniform area emission in OLETs with good stability and arbitrary tunability hinders their development in this field. Herein, an effective solution to obtain well‐defined area emission in lateral OLETs by incorporating a charge‐transport buffer (CTB) layer between the conducting channel and emitting layer is proposed. Comprehensive theoretical simulation and experimental results demonstrate redistributed potential beneath the drain electrode under the shielding effect of the CBT layer, resulting in a highly uniform current density. 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. RGB OLETs with uniform area emission are constructed, which show good gate tunable ability (ON/OFF ratio 106), high loop stability (over 200 cycles) and high aperture ratio (over 80%) due to the arbitrary tunability of the 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.