As a class of optoelectronic integrated devices, organic light-emitting field-effect transistors (OLETs) integrate two device functions, organic field-effect transistors (OFETs) and organic light-emitting diodes (OLEDs), in the same device, with high integration and simpler integration processes. It has important scientific and technical significance in the fields of novel flexible display and organic pumped laser.
In recent years, Dong Huanli's research group from the Organic Solids Laboratory, Institute of Chemistry, Chinese Academy of Sciences has been working on the preparation of OLET core high-mobility light-emitting organic semiconductor materials ( Nat. Commun., 2015, 6, 100032; J. Am. Chem. Soc., 2017, 139, 17261; J. Am. Chem. Soc., 2020, 142, 6332; Angew. Chem. Int. Ed., 2021. 60, 14902) and OLET device construction (Adv. Mater., 2019, 31, 1903175; Angew. Chem. Int. Ed., 2021, 60, 20274; Adv. Mater., 2021, 2007149; Adv. Mater., 2021, 2100704).
Facing the needs of diversified display applications such as morphological, low-cost, and easy customization, researchers have proposed a new type of traditional vertical OLET device with complex process, poor stability, and low aperture ratio caused by the linear light-emitting form of planar OLET devices. The planar surface light source exits the OLET device structure (CTB-OLET, Figure 1).
Figure 1 A new type of flat surface light source OLET display device primitive
In the device structure, a charge transport buffer layer (CTB layer) is introduced between the light-emitting unit and the transport layer, which effectively regulates the current distribution under the drain light-emitting layer and plays an important role in the emission of surface light sources. effect.
Simulations show that the introduction of the CTB charge transport layer in the planar OFET device changes the lateral electric field distribution in the traditional planar OFET device, thereby improving the uniformity of charge distribution under the drain electrode. This phenomenon is achieved by designing the split electrode device structure. Well confirmed.
Based on this device structure, a suitable light-emitting layer was introduced to prepare a flat surface light source OLET display device element with RGB three primary colors, which showed good gate control capability (on-off ratio>10 6 ) and was not immune to gate voltage. Affects the shape of the area light's glow.
Further due to the flexible design of the device structure, a large aperture ratio OLET display device based on a U-shaped drain electrode was studied and prepared (in the case of considering the area occupied by necessary components such as supporting circuits and switching transistors in the actual pixel, the opening rate can still be >80 percent ).
At the same time, as a unique voltage-driven display device, it is easy to achieve a saturated operating region, thus showing good stability independent of source-drain voltage. This large aperture ratio, flat-integrated OLET display device has unique advantages in low-temperature processing, light flexibility, and compatibility with OLED processes. good application prospects.
Recently, the related research results were published in Advanced Materials. The research work was supported by the National Natural Science Foundation of China, the Ministry of Science and Technology and the Chinese Academy of Sciences.