Metal nanowires (NWs) enable versatile applications in printed electronics and optoelectronics by serving as thin and flexible transparent electrodes. The performance of metal NWs as thin electrodes is highly correlated to the connectivity of NW meshes. The percolation threshold of metal NW films corresponds to the minimum density of NWs to form the transparent, yet conductive metal NW networks. Here, we determine the percolation threshold of silver NW (AgNW) networks by using morphological analysis and terahertz (THz) reflection spectroscopy. From the divergent behavior of carrier scattering time and the increase of carrier backscattering factor, the critical NW density at which crossover from Drude to non-Drude behavior of THz conductivity occurs can be unambiguously determined for AgNW thin films. Furthermore, the natural oxidation of AgNWs which causes the gradual reduction of the connectivity of the AgNW network is also realized by the THz spectroscopy. The selective oxidation of NW-to-NW junctions weakens the ohmic contact, and for AgNWs near a critical density, it can even lead to metal-insulator transition. The presented results offer invaluable information to accelerate the deployment of metal nanowires for next-generation electronics and optoelectronics on flexible substrates.

In this work, we demonstrate sputtered amorphous indium-gallium-zinc oxide thin-film transistors (a-IGZO TFTs) with a record high effective field-effect mobility of 174 cm(2)/V s by incorporating silver nanowire (AgNW) arrays to channel electron transport. Compared to the reference counterpart without nanowires, the over 5-fold enhancement in the effective field-effect mobility exhibits clear dependence on the orientation as well as the surface coverage ratio of silver nanowires. Detailed material and device analyses reveal that during the room-temperature IGZO sputtering indium and oxygen diffuse into the nanowire matrix while the nanowire morphology and good contact between IGZO and nanowires are maintained. The unchanged morphology and good interfacial contact lead to high mobility and air-ambient-stable characteristics up to 3 months. Neither hysteresis nor degraded bias stress reliability is observed. The proposed AgNW-mediated a-IGZO TFTs are promising for development of large-scale, flexible, transparent electronics.

In this study, an Ar/O2 plasma mixture treatment with different proportions of O2 was used to reduce the oxygen vacancy density in an amorphous indium gallium zinc oxide (a-IGZO) thin film. The objective was to enhance the field-effect carrier mobility in a thin-film transistor (TFT) with the IGZO film as the channel layer. Atomic force microscopy revealed that the roughness of the IGZO film after plasma treatment was higher than that of the untreated film; however, the surface roughness of the IGZO film decreased after the proportion of O2 was increased in the plasma. The Hall measurement results showed that the resistivity of the plasma-treated IGZO film increased with a decrease in the electron concentration in the film; in addition, the carrier mobility considerably increased. The IGZO TFT fabricated from this film exhibited a high field-effect carrier mobility of 36 cm2 V−1 s−1, a subthreshold swing (SS) of 1.25 V/decade, an I OFF current of 4.58 × 10−11 A, and an I ON/I OFF current ratio of 7.55 × 105. To further improve the device performance, the plasma-treated IGZO films were subjected to thermal annealing with the annealing temperature ranging from 100 °C to 300 °C. After the annealing process, the plasma-treated IGZO TFTs demonstrated a further improvement in the device performance with a field-effect carrier mobility of 38.8 cm2 V−1 s−1, SS of 0.7 V/decade, I OFF current of 1.04 × 10−11 A, and an I ON/I OFF current ratio of 9.93 × 106. In addition, a reliability test was performed to evaluate the stability of the IGZO TFT devices, which revealed that the threshold voltage maintained a high degree of stability during the long-term tests. Therefore, the plasma-treated IGZO TFTs with subsequent postgrowth annealing could be helpful for the fabrication of next-generation flat-panel displays.

This study developed flexible light-emitting diodes (LEDs) with warm white and neutral white light. A simple ultraviolet flip-chip sticking process was adopted for the pumping source and combined with polymer and quantum dot (QD) films technology to yield white light. The polymer-blended flexible LEDs exhibited higher luminous efficiency than the QD-blended flexible LEDs. Moreover, the polymer-blended LEDs achieved excellent color-rendering index (CRI) values (Ra = 96 and R9 = 96), with high reliability, demonstrating high suitability for special applications like accent, down, or retrofit lights in the future. In places such as a museum, kitchen, or surgery room, its high R9 and high CRI characteristics can provide high-quality services.

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