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Highly piezoelectric lead-free thin films of (K0.5Na0.5)NbO3 + x mol% Na(I) and K(I) (KNN, x = 0–50 mol%) were fabricated using a sol-gel method on Pt (111)/Ti/SiO2/Si(100) substrates and the effects of additives on microstructure, oxygen vacancies, and electrical properties of the proposed samples were investigated. Excess quantities of Na(I) and K(I) were shown to decrease the formation of secondary phases and promote the effective growing of the grains. The addition of these elements was also shown to inhibit the formation of alkaline ion vacancies and decrease the leakage current density. Our findings indicate that the crystallinity and microstructure of the samples have a stronger effect than the oxygen vacancies on the piezoelectric properties of KNN films. Non-stoichiometric KNN films showed the highest remnant polarization (Pr = 11.2 μC/cm2), piezoelectric coefficient (d33 = 40.23 pm/V), voltage coefficient (g33 = 7.9 mm V/N), and lowest leakage current (∼3.46 × 10−7 A/cm2) when the excess ratio was 40 mol% following annealing at 700°C. Our results also demonstrate that the transport mechanism of the films is governed by Ohmic behavior under low electric fields and the effects of Poole-Frenkel emission under a strong electric field.

In this paper, a thermally crosslinkable 9,9-Bis[4-[(4-ethenylphenyl)methoxy]phenyl]-N2,N7-di-1-naphthalenyl-N2,N7-diphenyl-9H-fluorene-2,7-diamine (VB-FNPD) film served as the hole transporting layer (HTL) of perovskite CsPbBr3 quantum-dot light-emitting diodes (QD-LEDs) was investigated and reported. The VB-FNPD film crosslinked at various temperatures in the range of 100~230 °C followed by a spin-coating process to improve their chemical bonds in an attempt to resist the erosion from the organic solvent in the remaining fabrication process. It is shown that the device with VB-FNPD HTL crosslinking at 170 °C has the highest luminance of 7702 cd/m2, the maximum current density (J) of 41.98 mA/cm2, the maximum current efficiency (CE) of 5.45 Cd/A, and the maximum external quantum efficiency (EQE) of 1.64%. Our results confirm that the proposed thermally crosslinkable VB-FNPD is a candidate for the HTL of QD-LEDs.

The unipolar resistive switching behavior of Pt/LixZn1−xO/Pt structures fabricated via radio-frequency magnetron sputtering is investigated. Various Li doping concentrations influence the defect types (i.e., VO, Lii, and LiZn) in LixZn1−xO films for adjustable resistance ratio. The resistance ratio reaches 108 due to the minimized leakage current in the high-resistance state (HRS) at 6 at. % Li dopants. The dominant conduction mechanisms are explained in terms of Ohmic behavior and Poole-Frenkel (PF) emission. The coefficient r of the PF emission in the HRS is evaluated to confirm that the total number of defects in LixZn1−xO films decreases with increasing Li content.