Graphene‐Based Intrinsically Stretchable 2D‐Contact Electrodes for Highly Efficient Organic Light‐Emitting Diodes

Abstract

Intrinsically stretchable organic light‐emitting diodes (ISOLEDs) are becoming essential components of wearable electronics. However, the efficiencies of ISOLEDs have been highly inferior compared with their rigid counterparts, which is due to the lack of ideal stretchable electrode materials that can overcome the poor charge injection at 1D metallic nanowire/organic interfaces. Herein, highly efficient ISOLEDs that use graphene‐based 2D‐contact stretchable electrodes (TCSEs) that incorporate a graphene layer on top of embedded metallic nanowires are demonstrated. The graphene layer modifies the work function, promotes charge spreading, and impedes inward diffusion of oxygen and moisture. The work function (WF) of 3.57 eV is achieved by forming a strong interfacial dipole after deposition of a newly designed conjugated polyelectrolyte with crown ether and anionic sulfonate groups on TCSE; this is the lowest value ever reported among ISOLEDs, which overcomes the existing problem of very poor electron injection in ISOLEDs. Subsequent pressure‐controlled lamination yields a highly efficient fluorescent ISOLED with an unprecedently high current efficiency of 20.3 cd A−1, which even exceeds that of an otherwise‐identical rigid counterpart. Lastly, a 3 inch five‐by‐five passive matrix ISOLED is demonstrated using convex stretching. This work can provide a rational protocol for designing intrinsically stretchable high‐efficiency optoelectronic devices with favorable interfacial electronic structures.

Intrinsically Stretchable Phosphorescent Light-Emitting Materials for Stretchable Displays

“…The increased luminance and decreased current of the isp- EML at 10:1:1 and 10:1:2.5 ratios improved the device efficiency. To the best of our knowledge, the maximum efficiency of an intrinsically stretchable fluorescent light-emitting layer obtained by a solution process is 20.3 cd/A. , On the other hand, the isp- EML showed a much higher current efficiency (25.3 cd/A) than other stretchable fluorescence-emitting materials, as shown in Figure g. Furthermore, in contrast with the theoretical EQE limit of first-generation fluorescence emitters such as SY (EQE ∼ 5%), the isp- EML showed an EQE of 6.8%, resulting in substantial improvements in both EL efficiency and stretchability …”

Stable and Transparent Ca2+-Cross-Linked Alginate Composite Films for EMI Shielding and Joule Heating

“…The conventional indium tin oxide film possesses strong EMI shielding efficiency and ideal transparency (30 dB@80%), whereas its inherent brittleness limits further application for flexible electronics. Alternative materials such as graphene, MXene, , carbon nanotubes (CNTs), ultrathin silver layer, − metallic mesh, − and metal nanowires, , were developed for high-quality transparent EMI shielding materials with favorable flexibility. One-dimensional (1D) silver nanowires (AgNWs) with high electrical conductivity and an appropriate aspect ratio can be fabricated as a continuous conductive network on a transparent substrate to design composite films with less thickness, extremely high conductivity, and strong EMI shielding ability. − The assembled AgNW networks are easily formed via facile full solution methods.…”

Intrinsically stretchable three primary light-emitting films enabled by elastomer blend for polymer light-emitting diodes

“…In the case of intrinsic stretchability, substantial developments have been reported in molecular design, molecular interaction control, and nanoconfinement effects (19)(20)(21)(22)(23)(24)(25)(26)(27). Kim and Park (22) introduced intrinsically stretchable light-emitting polymer films based on molecular interaction engineering using plasticizers.…”