Characteristics of Perovskite Solar Cells According to Thickness of Doped ZnGa2O4 Down-Converting Thin Film

A ZnGa2O4:Eu3+ layer was deposited on the incident surface of a perovskite solar cell (PSC) to convert ultraviolet rays into current within the solar cell. The ZnGa2O4:Eu3+ layer was deposited using the sol–gel method, and the thickness of the film was controlled using the number of spin coatings. When the coating was applied six times, a layer with almost no oscillation due to reflection was fabricated. It was confirmed that the efficiency of the PSC was not adversely affected by the coating. In addition, generation of a current by converting ultraviolet radiation within the solar cell was confirmed.

A Green Process to Prepare Hydrophobic and Transparent CNT-Based Surface

A green process to prepare the hydrophobic and transparent CNT-based surface was developed without using any toxic chemicals, solvents or gases. CNT brush (CNT-b) powder, which was prepared by the repeated CVD, was the main material to prepare the desired surface. An adhesive layer of ethyl cellulose (EC) was spin coated on the glass substrate, where EC formed a networked porous microstructure. A low concentration CNT-b suspension was obtained by sonication of the mixture of CNT-b powders, sodium dodecylbenzenesulfonate (SDBS) and deionized water. To obtain the stabilized CNT-b suspension, it was found that 40 min of sonication time and SDBS/CNT-b weight ratio being 0.1 were required. The target surface was then prepared by spin coating CNT-b suspension on the EC coated glass. The contact angle of the prepared surface was around 120o and the optical transmittance was around 93% for the visible light. Either increasing the number of spin coatings or increasing the concentration of CNT-b suspension could slightly increase the contact angle to around 130o but the optical transmittance significantly reduce to about 75%, leading to a semi-transparent sample.

Fabrication and Electrical Properties of P(VDF-TrFE)/Bi3.5Nd0.5Ti3O12 Bi-Layer Composite Ferroelectric Thin Films

The microstructure and electrical properties of P(VDF-TrFE)/Bi3.5Nd0.5Ti3O12bi-layer composite ferroelectric thin films deposited on Pt/Ti/SiO2/Si using two successive spin coatings were investigated. It shows the pores in Bi3.5Nd0.5Ti3O12(BNT) films were effectively suppressed by the presence of P(VDF-TrFE) copolymer films by SEM. The ferroelectric, leakage and dielectric properties of the thin films with different thickness ratio of P(VDF-TrFE) and BNT thin films were measured. With increasing the thickness of P(VDF-TrFE), the remnant polarization, coercive electric field, leakage current density and dielectric constant of thin films were all decreased (except pure P(VDF-TrFE) thin film). Results indicate that the key electrical properties were improved effectively by a little loss of the remnant polarization, which infers potential application in the filed of ferroelectric memory.

Enhancement of Ionic Conductivity in La2Mo2O9-Based Nanocrystalline Films Synthesized by a PVP Assisted Sol-Gel Method

High-quality 5% W- and Gd-doped La2Mo2O9 nanocrystalline films were successfully synthesized on poly-alumina substrates via a PVP-assisted sol-gel method with inorganic salts as precursors, combined with the rapid thermal annealing and novel three stages annealing procedures. Dense and uniform La2Mo2O9-based films with 90 nm in grain size and 1 μm in thickness were obtained by only twice spin coatings and sintering at 600 oC. The electrical conductivity of the films at 600 oC reaches 0.028 and 0.025 S/cm for W- and Gd-doped samples, respectively.