Inverted Tand OLED Intermediate Layer Suppresses Metal Diffusion

The patent introduces an electron-relay layer as an intermediary between the charge generation layer and the electron-injection buffer layer. This relay layer acts as a mediator that prevents direct contact and metal diffusion between the charge generation layer and the alkali metal-containing buffer layer, while still enabling electron transport functionality. The relay layer thus resolves the contradiction by allowing electron injection efficiency to be maintained through the buffer layer while preventing the harmful metal diffusion into the charge generation layer.

The intermediate layer is segmented into three distinct sub-layers: a charge generation layer, an electron-relay layer, and an electron-injection buffer layer. This segmentation separates the functions of charge generation, electron relay/transport, and electron injection, while physically isolating the alkali metal-containing buffer layer from the charge generation layer to prevent metal diffusion. The segmentation allows each layer to optimize its specific function without interfering with or contaminating other layers.

The intermediate layer is divided into three functional sub-layers with distinct roles. While this segmentation increases structural complexity compared to a single-layer intermediate layer, it provides precise control over metal diffusion through the physical separation of the alkali metal-containing buffer layer from the charge generation layer. Each layer can be optimized and manufactured with specific material properties to achieve the desired diffusion control and emission efficiency.

The electron-relay layer serves as an intermediary that simplifies the manufacturing process by providing a universal interface between the charge generation layer and the electron-injection buffer layer. This relay layer can be formed using standard vacuum deposition techniques and provides a controlled barrier that prevents metal diffusion while maintaining electron transport, thus achieving both manufacturing ease and diffusion control.

The electron-relay layer acts as an intermediary that prevents metal diffusion from the electron-injection buffer layer into the charge generation layer and EL layers. By blocking metal contamination, the relay layer prevents the degradation of charge generation efficiency and electron transport properties that would otherwise lead to increased drive voltage. This allows the tandem structure to maintain high current efficiency without the penalty of elevated drive voltage caused by metal incorporation.

The three-layer segmented structure of the intermediate layer isolates the alkali metal-containing electron-injection buffer layer from the sensitive charge generation layer and EL layers. This segmentation prevents metal diffusion that would increase drive voltage, while still allowing the tandem structure to achieve high current efficiency through the combined operation of multiple EL layers with the intermediate layer facilitating efficient charge generation and electron injection.