Highly Efficient and Stable Organic Light‐Emitting Diodes with Inner Passivating Hole‐Transfer Interlayers of Poly(amic acid)‐Polyimide Copolymer

Abstract

Ensuring the long‐term stability of high‐performance organic light‐emitting diodes (OLEDs) has remained a great challenge due to their limited lifetime and durability. Herein, a novel functional interlayer consisting of a poly(amic acid)‐polyimide copolymer is introduced for use in OLEDs. It is shown that an OLED sample with a polyimide‐copolymer interlayer exhibits high peak brightness of nearly 96 000 cd m−2 and efficiency of ≈92 cd A−1, much higher than those (≈73 000 cd m−2 and ≈83 cd A−1) of a well‐organized reference OLED. Moreover, the growth of dark spots is strongly suppressed in the sample OLED and the device lifetime is extended considerably. Further, highly stable and uniform large‐area OLEDs are successfully produced when using the interlayer. These improvements are ascribed not only to the excellent film‐forming and hole‐transferring properties but also to the inner passivating capability of the polyimide‐copolymer interlayer. The results here suggest that the introduction of an inner passivating/encapsulating hole‐transferable polyimide‐copolymer interlayer together with conventional external encapsulation technology represents a promising breakthrough that enhances the longevity of high‐performance next‐generation OLEDs.

Research Progress and Application of Polyimide-Based Nanocomposites

“…The deposition method uses physical deposition, chemical deposition, electroless coating, and other techniques to deposit nanostructures on the surface of PI and obtain the composite materials [ 121 , 122 , 123 , 124 ]. Wang et al [ 125 ] used the electroless coating process to prepare blended fabrics with a multilayer structure of nickel–cobalt–ferrum–phosphorus/polyaniline/PI(Ni-Co-Fe-P/PANI/PI), which prepared high-efficiency electromagnetic shielding materials with dense metal layers, low reflection, and strong absorption characteristics, especially meeting the requirements of high temperature, high pressure, or foldable systems ( Figure 11 ).…”

Electric‐Field‐Induced Alignment of Functionalized Carbon Nanotubes Inside Thermally Conductive Liquid Crystalline Polyimide Composite Films

“…Polyimide (PI) films are known for their exceptional electrical insulation, mechanical strength, heat resistance, and radiation resistance, etc. [1][2][3] These properties have made them a popular choice for high-precision intelligent control systems, 5G communication terminals, and base stations. However, their intrinsic thermal conductivity coefficients (λ) are typically quite low, which limits their ability to effectively conduct or dissipate heat in high-power electronic and electrical equipments.…”

“…Polyimide (PI) films are known for their exceptional electrical insulation, mechanical strength, heat resistance, and radiation resistance, etc [1–3] . These properties have made them a popular choice for high‐precision intelligent control systems, 5G communication terminals, and base stations.…”

Ligand‐Mediated Revival of Degraded α‐CsPbI3 to Stable Highly Luminescent Perovskite

“…Lead halide perovskites (LHPs) (APbX 3 , where A is CH 3 NH 3 + , Cs + , or FA + and X is Cl − , Br − , or I − ) have drawn immense interest to the scientific community due to their tuneable optical properties along with high quantum yields (QY≈100 %) [1, 2] . However, one of the challenging issues in these materials is environmental stability, because those perovskites are vulnerable in moisture, ambient oxygen, incident light, and applied external bias [3] . The chemical composition, crystallite size, surface ligands, defect states, and synthetic conditions affect the stability [4] .…”