ABSTRACT
In order to ensure high-performance semitransparent perovskite solar cells (ST-PSCs), the deposition of high-quality scalable transparent cathodes on ST-PSCs at room temperature is necessary. In this study, we designed an amorphous InGaTiO (IGTO) electrode, prepared by linear facing target sputtering (LFTS) as a transparent cathode for ST-PSCs. Even in the room temperature sputtering process, the amorphous IGTO cathode showed a low sheet resistance of 9.895 Ohm/square and a high optical transmittance of 87.53% without the occurrence of in situ or postannealing, unlike Sn-doped In2O3 (ITO) electrodes. Due to its complete amorphous structure and low energy sputtering, the amorphous IGTO electrode showed superior mechanical properties, when compared to other typical crystalline ITO films. Additionally, the LFTS process led to a low energy deposition of the amorphous IGTO cathode on ST-PSCs, and did not result in plasma damage on perovskite active layers, which is often typical in conventional situations of direct current sputtering. On the basis of these optimized plasma damage-free sputtering conditions, we examined the feasibility of LFTS-grown IGTO cathodes for ST-PSCs. In our results, we observed that a similar performance of the ST-PSC with an IGTO cathode with the opaque PSC with Ag cathode, indicated that amorphous IGTO cathode is a prospective transparent cathode for ST-PSCs on both rigid or flexible substrates.
ABSTRACT
We investigated simple and unrestricted brush-paintable black electrodes for poly(vinylidene fluoride) (PVDF)-based artistic flexible piezoelectric devices. The conductive black ink for paintable electrodes was synthesized by mixing poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and typical black ink and optimizing the mixing ratio. At an optimal mixing ratio, the brush-paintable black electrodes showed a sheet resistance of 151 Ω/sq and high coatability for flexible piezoelectric devices. Noticeably, higher black ink ratios increased adhesion forces, while diminished the shear flow of the conductive black ink. In addition, the optimized conductive black electrode exhibited an outstanding level of mechanical flexibility due to good adhesion between the black electrode and the PVDF substrate. During the repeated inner/outer bending fatigue tests with high strain, no resistance change confirmed the outstanding flexibility of the brush-paintable conductive electrode. As a promising application of the brush-paintable optimized black electrode, we suggested highly flexible piezoelectric devices that can be used. A PVDF-based piezoelectric speaker and a generator with the brush-paintable black electrode showed acoustic and output signal values approximate to those of metallic electrodes fabricated by vacuum-based high-cost thermal evaporators. Our experiment demonstrated a cost-efficient and simple process for fabricating brush-paintable electrodes, applicable to the flexible PVDF-based piezoelectric devices.
ABSTRACT
We investigated the deposition rate effect on the optical, electrical, and morphological characteristics of thermally evaporated WO3-x/Ag/WO3-x (WAW) multilayer electrodes. By controlling the deposition rate of the WO3-x and Ag layers, we can control the interface structure between WO3-x and Ag and improve both the optical and electrical properties of the thermally evaporated WAW multilayer electrodes. At the optimized deposition rate of WO3-x (2.5 Å/sec) and Ag (10 Å/sec), the symmetric WAW multilayer exhibited a high optical transmittance of 92.16% at a 550 nm wavelength and low sheet resistance of 3.78 Ω/square. During repeated bending, rolling, and twisting, there was no resistance change indicating the superior flexibility of WAW multilayer electrodes. As a promising application of the WAW multilayer electrodes, we suggested the transparent and flexible thin film heaters (TFHs) to substitute the high cost indium tin oxide-based TFHs. In comparison to the ITO-based TFHs, the WAW based TFHs showed higher convective heat transfer property and higher saturation temperatures are achieved at lower input voltages due to lower sheet resistance. This indicates that the WAW multilayer is suitable as the electrode for high performance transparent and flexible TFHs.
