UV/Ozone‐Induced Interface Engineering for High‐Performance Horizontal Organic Light‐Emitting Transistors Operating at Low Voltage

Abstract Multifunctional organic light‐emitting transistors (OLETs), which combine electric‐switching and light‐producing capabilities into a single device, are attracting increasing interest as promising candidates for new‐generation display technology. Despite advancements in the design of organic luminescent materials and the optimization of device geometry configurations, maintaining operating voltage low while enhancing optical performances remains a key challenge in horizontally structured OLETs. Here, a simple and effective interfacial engineering strategy is employed to improve the optical properties of horizontal OLETs operating at low voltage, by introducing ultraviolet ozone (UVO)‐induced surface modification on high‐k dielectrics. It takes the role to not only control the surface activation states of dielectric layers but also optimize the growth dynamics behavior of channel film benefitting from the strong interfacial interaction between chemically modified dielectric surface and channel seed molecules. The optimized horizontal‐channel OLET exhibits a significantly high brightness of 9,484 cd m⁻², more than 25 times greater than that of untreated OLETs (347 cd m⁻²), along with a peak EQE of 9.64%, a low operating voltage of 15 V, and good dynamic gate stress stability, outperforming other reported horizontal‐channel high‐performance OLETs. This work demonstrates that dielectric/semiconductor interface engineering is essential for high‐performance transistor‐based optoelectronic devices including horizontal OLETs.