No abstract

No abstract

which opens the door to applications on flexible substrates. However, the surface hydrophobicity of plastic substrates remains a big obstacle that inhibits the initial nucleation for the ALD growth process. To solve this problem, an AZO buffer layer can be introduced on plastic substrates. Such a layer can be prepared via multiple physical methods, such as magnetron sputtering, [11] electron beam evaporation, [12] or pulsed laser deposition. [13] Different from chemical deposition methods, the physical deposition usually leads to a denser film without the basic requirements of the hydroxyl groups absorbed on the plastic surface. Here, we selected sputtering method because it is cheap and convenient. Unfortunately, the AZO films sputtered at low temperatures usually have a large sheet resistance and are not suitable to serve as the electrodes of capacitors. Hence, it is necessary to deposit an ALD-AZO layer on the sputtered-AZO film to improve the overall conductivity. To further improve the flexibility and conductivity, silver nanowires (AgNWs) have been added into AZO films to form the composite AZO/AgNWs/AZO electrodes which showed a very low sheet resistance below 10 Ω, as can be seen from our previous work. [14] In terms of dielectrics, high-k materials have always been regarded as promising candidates for transparent electronics because most of them have wide bandgaps. Capacitors with large capacitance, small featured size, and low power consumption can be realized by employing high-k materials as dielectrics. Many high-k materials including Al 2 O 3 , [15] TiO 2 , [16] HfO 2 , [17] and ZrO 2 [18] have been widely investigated during the past few years. Among them, ZrO 2 demonstrated a great potential due to its high permittivity of about 25 and a relatively large bandgap of about 5.6 eV. [19] In addition, its excellent temperature stability and low permeation rates for ambient gases are attractive to improve the device reliability. [20,21] In our recent work, the AZO/ ZrO 2 /AZO capacitors showed an ultralow leakage current while maintaining a large capacitance density. [22] In this work, transparent and flexible capacitors were directly fabricated on polyethylene naphthalate (PEN) substrates. The capacitors showed a relatively large capacitance density and an ultralow leakage current. Capacitors with and without AgNWs embedded in the AZO bottom electrode can both work normally under an outward bending radius of 7 mm. However, capacitors with the composite AZO/AgNWs/AZO electrodes showed superior antifatigue properties than capacitors with the ordinary AZO electrodes without AgNWs.Transparent and flexible capacitors with ZrO 2 as the dielectric layer are fabricated directly on polyethylene naphthalate (PEN) substrates by an in situ atomic layer deposition method. The hybrid AlZnO and silver nanowires serve as the bottom electrode. The capacitors exhibit a high capacitance density of 15.2 fF µm −2 and an ultralow leakage current (1.0 × 10 −9 A cm −2 at 1 V). Bending tests reveal that the capacitors can be ou...

No abstract

No abstract