No abstract

A novel approach for the fabrication of ultra-smooth and highly bendable substrates consisting of metal grid-conducting polymers that are fully embedded into transparent substrates (ME-TCEs) was successfully demonstrated. The fully printed ME-TCEs exhibited ultra-smooth surfaces (surface roughness ~1.0 nm), were highly transparent (~90% transmittance at a wavelength of 550 nm), highly conductive (sheet resistance ~4 Ω ◻−1), and relatively stable under ambient air (retaining ~96% initial resistance up to 30 days). The ME-TCE substrates were used to fabricate flexible organic solar cells and organic light-emitting diodes exhibiting devices efficiencies comparable to devices fabricated on ITO/glass substrates. Additionally, the flexibility of the organic devices did not degrade their performance even after being bent to a bending radius of ~1 mm. Our findings suggest that ME-TCEs are a promising alternative to indium tin oxide and show potential for application toward large-area optoelectronic devices via fully printing processes.

Organic light emitting diodes (OLEDs), which possess wonderful device performance and mechanical robustness have been extensively explored in textile lighting applications. In this work, an ITO‐free, PEDOT:PSS/Ag‐fiber hybrid transparent conducting electrode (TCE) embedded in polymeric substrate (denoted as hybrid‐fiber TCE henceforth) for the fabrication of large‐area OLEDs is designed. The optimum hybrid‐fiber TCE with a pitch of 150 µm shows extraordinarily low sheet resistance (Rsheet = 1.3 Ω ▫−1) and exceptional mechanical flexibility, exhibiting ≈100% Rsheet retention at a bending radius of up to ≈0.5 mm. The device performance of the resulting OLEDs based on hybrid‐fiber TCEs (fiber‐OLEDs) is on‐par with that of ITO‐based OLED analogues. More fascinatingly, organic light emitting fibers (OLEFs), obtained via slitting the fiber‐OLEDs, display a maximum luminance efficiency of ≈38.2 cd A−1 and a maximum external quantum efficiency of ≈10.9%, which surpasses all previously reported results. In addition, the OLEFs are mechanically robust and able to withstand a high degree of deformation, thus can be woven into fabric matrix for smart textile application. The vacuum‐free, scalable fabrication of the high performance OLEFs demonstrated herein is significant for the development of extremely large‐area smart textile applications.

Ecofriendly cation metal oxide quantum dots (QDs) are one of the promising candidates to replace for QDs containing expensive indium (In) or hazardous Cd-and Pb-elements. Super-E g excitation wavelength (λ ex ) dependent Zn i -V O complex defects related characteristic emissions of green, yellow, and orange-red from ZnO QDs are completely inhibited by reducing oxygen vacancies through the hybridization of Zn interstitials in ZnO QDs with antibonding Ostates of graphene oxide (GO) QDs. Thus, only λ ex independent violet-purple-blue (V-P-B) emission resulting from transitions among Frenkel pairs (Zn i 0 -V Zn ) and the defects Zn i 0 -O i in ZnO-GO QDs with a high photoluminescence quantum yield (PLQY) of 92% is successfully achieved. White-light emission from PL QD-LEDs is achieved using a mixture of ZnO and ZnO-GO QDs with CIE (0.32, 0.34) excited by a UV LEDs chip (λ = 365 nm). Further, ZnO-GO QD-based deep-blue LEDs (λ = 438 nm) with luminance of 1980 cd/m 2 , a luminous efficacy (LE) of 2.53 cd/ A, and external quantum efficiency (EQE) of 2.78% with CIE (0.16, 0.11) are also realized.

No abstract