Electroluminescent (EL) devices have been extensively integrated into multi-functionalized electronic systems in the role of the vitally constituent light-emitting part. However, the lifetime and reliability of EL devices are often severely restricted by concomitant damage, especially when the strain exceeds the mechanical withstanding limit. We report a self-healable EL device by adopting a modified self-healable polyacrylic acid hydrogel as the electrode and a self-healable polyurethane as a phosphor host to realize the first omni-layer-healable light-emitting device. The physicochemical properties of each functionalized layer can be efficiently restored after experiencing substantial catastrophic damage. As a result, the luminescent performance of the self-healable EL devices is well recovered with a high healing efficiency (83.2% for 10 healing cycles at unfixed spots, and 57.7% for 20 healing cycles at a fixed spot). In addition, inter-device healing has also been developed to realize a conceptual “LEGO”-like assembly process at the device level for light-emitting devices. The design and realization of the self-healable EL devices may revive their performance and expand their lifetime even after undergoing a deadly cut. Our self-healable EL devices may serve as model systems for electroluminescent applications of the recently developed ionically conductive healable hydrogels and dielectric polymers.

In this paper, we have demonstrated the dual role of boron doping in enhancing the device performance parameters as well as the device stability in low temperatures (200 °C) sol-gel processed ZnO thin film transistors (TFTs). Our studies suggest that boron is able to act as a carrier generator and oxygen vacancy suppressor simultaneously. Boron-doped ZnO TFTs with 8 mol. % of boron concentration demonstrated field-effect mobility value of 1.2 cm2 V−1 s−1 and threshold voltage of 6.2 V, respectively. Further, these devices showed lower shift in threshold voltage during the hysteresis and bias stress measurements as compared to undoped ZnO TFTs.

Abstract

Weakly coupled relaxors based on compositions (1‐x) BaTiO3‐xBiMeO3, where Me is a metal ion, have attracted attention as potential candidates for high‐temperature high‐energy density capacitors. However, the necessary Bi content is typically high with x = 0.3‐0.4. In order to reduce problems associated with compatibility for base metal electrodes and due to additional problems due to Bi volatility, it is desirable to lower the Bi content in the overall composition for these materials. Here, we have explored a possible way to reduce BiMeO3 content through additional A‐site substitutions viz. Ca and Sn. The relaxor nature and energy storage properties of Sn‐modified (Ba,Ca)(Ti)O3‐BiScO3 ceramics were determined from their dielectric and ferroelectric behaviors. The material showed attractive properties in terms of a frequency‐independent (200 Hz‐1 MHz) dielectric response from room temperature to 200°C, extremely low loss and high‐energy storage efficiency. The structural phenomena underlying the functional properties of Sn‐modified (Ba,Ca)TiO3‐BiScO3 are characterized from temperature‐dependent X‐ray diffraction and pair distribution function analysis. In broader terms, the study illustrates the potential for tailoring relaxor behavior in Pb‐free ferroelectrics by combining phenomena, such as quantum fluctuations and lone pair stereochemical effect associated with different solid‐solution substitutions.

In many ferroelectrics, large electromechanical strains are observed near regions of composition- or temperature- driven phase coexistence. Phenomenologically, this is attributed to easy re-orientation of the polarization vector and/or phase transition, although their effects are highly convoluted and difficult to distinguish experimentally. Here, we used synchrotron X-ray scattering and digital image correlation to differentiate between the microscopic mechanisms leading to large electrostrains in an exemplary Pb-free piezoceramic Sn-doped barium calcium zirconate titanate. Large electrostrains of ~0.2% measured at room-temperature are attributed to an unconventional effect, wherein polarization switching is aided by a reversible phase transition near the tetragonal-orthorhombic phase boundary. Additionally, electrostrains of ~0.1% or more could be maintained from room temperature to 140 °C due to a succession of different microscopic mechanisms. In situ X-ray diffraction elucidates that while 90° domain reorientation is pertinent below the Curie temperature (TC), isotropic distortion of polar clusters is the dominant mechanism above TC.