A robust vertical nanoscaffold for recyclable, paintable, and flexible light-emitting devices

Abstract

Organic light-emitting devices are key components for emerging opto- and nanoelectronics applications including health monitoring and smart displays. Here, we report a foldable inverted polymer light-emitting diode (iPLED) based on a self-suspended asymmetrical vertical nanoscaffold replacing the conventional sandwich-like structured LEDs. Our empty vertical-yet-open nanoscaffold exhibits excellent mechanical robustness, proven by unaltered leakage current when applying 1000 cycles of 40-kilopascal pressure loading/unloading, sonication, and folding, with the corresponding iPLEDs displaying a brightness as high as 2300 candela per square meter. By using photolithography and brush painting, arbitrary emitting patterns can be generated via a noninvasive and mask-free process with individual pixel resolution of 10 μm. Our vertical nanoscaffold iPLED can be supported on flexible polyimide foils and be recycled multiple times by washing and refilling with a different conjugated polymer capable of emitting light of different color. This technology combines the traits required for the next generation of high-resolution flexible displays and multifunctional optoelectronics.

Large‐Area Deep‐Blue Polymer Light‐Emitting Diodes with Well‐Resolved Emission from Planar Conformational Segments Fabricated via Brush Coating

“…To verify this hypothesis, we also explored the horizontal emitting dipole orientation (EDO) of PODPF in various states by performing angle‐dependent polarization‐resolved PL intensity measurements (Figures 2e and S7, Supporting Information). [ 13 ] As shown in Figure 2e, the Θ // values of the pristine spin‐coated and brush‐coated PODPF films estimated from the simulated curves are equal to ≈100% and 99%, respectively, indicating isotropic behavior. However, the Θ // of the brush‐coated β‐conformational film is 92%, which is lower than that of the spin‐coated β‐conformational film (99%), suggesting preferentially horizontal EDO.…”

“…[ 18 ] Unlike other methods, brush coating is a unique and efficient technique that not only enables the preparation of continuous and uniform emissive films but also induces anisotropic intrachain and interchain arrangements, which can precisely tune their conformational behavior and improve photophysical properties. [ 12,13,19–21 ] Therefore, optimizing the hierarchical structure of LCPs in solid films via brush coating is an effective strategy for fabricating highly efficient large‐area PLEDs ( Scheme a). [ 20 ] However, compared with the small‐area uniform films obtained via spin coating, the large‐area LCP films produced via brush coating exhibit uncontrollable nonuniform morphologies, which may induce undesirable photophysical characteristics such as long‐wavelength green‐band emission and low efficiency, although these problems may be partially resolved by optimizing technological conditions (Scheme 1b).…”

“…[3,[5][6][7] Compared with the smallarea PLEDs fabricated via spin coating, printed large-area PLEDs have several advantages, such as high material yield, low fabrication cost, and room-temperature processing. [8][9][10][11] Up to date, various printing techniques have been developed to fabricate large-area PLEDs, including brush coating, [12,13] blade coating, [14][15][16] inkjet printing, [17] and others. [18] Unlike The fabrication of large-area printed deep-blue polymer light-emitting diodes (PLEDs) is a prerequisite for solid-state lighting and flat-panel displays.…”

“…[ 3,5–7 ] Compared with the small‐area PLEDs fabricated via spin coating, printed large‐area PLEDs have several advantages, such as high material yield, low fabrication cost, and room‐temperature processing. [ 8–11 ] Up to date, various printing techniques have been developed to fabricate large‐area PLEDs, including brush coating, [ 12,13 ] blade coating, [ 14–16 ] inkjet printing, [ 17 ] and others. [ 18 ] Unlike other methods, brush coating is a unique and efficient technique that not only enables the preparation of continuous and uniform emissive films but also induces anisotropic intrachain and interchain arrangements, which can precisely tune their conformational behavior and improve photophysical properties.…”

Increasing the operating lifetime of green phosphorescent organic light emitting diodes by reducing charge accumulation at the interface

“…In recent years, organic light-emitting diodes (OLEDs) have been developed rapidly due to their excellent performance characteristics, such as being self-luminous, highly efficient, flexible and enabling full-color displays. [1][2][3][4][5][6][7][8] However, the stability problem of OLEDs still exists, which hinders the commercial application of OLEDs. Therefore, it has become an important research topic to explore the degradation mechanisms and fabricate long lifetime OLEDs.…”