Enhancing DSSC Performance through Manipulation of the Size of ZnO Nanorods.

The synthesis of one-dimensional zinc oxide nanorod photoelectrodes through a chemical solution method and their application in dye-sensitized solar cells are described in this paper. A multiple growth approach was used to fabricate zinc oxide nanorods with varying length-to-diameter ratios, and their dye adsorption properties were characterized using ultraviolet-visible spectroscopy. The zinc oxide photoelectrodes with different length-to-diameter ratios were subsequently incorporated into dye-sensitized solar cells, and their performance and carrier lifetime were analyzed using a solar simulator, monochromatic incident photon-to-electron conversion efficiency, and electrochemical impedance spectroscopy.

Suppression of SnS Secondary Phase on CuZnSnS Solar Cells Using Multi-Metallic Stacked Nanolayers.

In CuZnSnS (CZTS) solar cells, it is crucial to suppress the generation of and remove the SnS secondary phase to improve the solar cell characteristics, as the SnS secondary phase affects the barrier for carrier collection and diode characteristics of the device. In this study, the nano-metallic precursor was modified to effectively suppress the generation of the SnS secondary phase on the surface and simultaneously improve the uniformity and quality of the thin film. The CZTS bifacial solar cells prepared via the proposed method exhibited significantly improved junction-rectifying characteristics, as the efficiency was improved to 1.

Location-Optoelectronic Property Correlation in ZnO:Al Thin Film by RF Magnetron Sputtering and Its Photovoltaic Application.

In this study, a radio-frequency magnetron sputter system was used to deposit AlO doped ZnO (AZO) thin films at room temperature, and the soda lime glass (SLG) substrates were placed at different zones relative to the center of the sample holder under the target. The samples were then analyzed using an X-ray diffractometer, Hall-effect measurement system, UV-visible spectrophotometer, and X-ray photoelectron spectroscopy. It was found that the electrical, structural, and optical properties of AZO films strongly depend on the target racetrack.

Enhanced omnidirectional light harvesting in dye-sensitized solar cells with periodic ZnO nanoflower photoelectrodes.

In this study, two-dimensional ZnO nanoflower photoelectrodes were prepared using a chemical solution method and applied to dye-sensitised solar cells. By growing ZnO nanoflowers with different lengths on the photoelectrodes, the effects of the ZnO nanoflowers on the omnidirectional light-harvesting and broadband of dye-sensitised solar cells were investigated. According to the field emission scanning electron microscope and UV-Vis-NIR measurements of the prepared ZnO nanoflowers at different lengths, it can be determined that the amount of dye adsorption and degree of light scattering are affected by the lengths of the nanoflowers.

Enhanced omnidirectional and weatherability of CuZnSnSe solar cells with ZnO functional nanorod arrays.

This paper presents the use of nanorods of different sizes, deposited from a chemical solution, as an antireflection layer in copper-zinc-tin selenide (CZTSe) solar cells. With the aid of the nanorods, the surface reflection of the CZTSe solar cells was reduced from 7.76% to 2.

CuZnSnSe Thin Film Solar Cell with Depth Gradient Composition Prepared by Selenization of Sputtered Novel Precursors.

In this study, we proposed a new method for the synthesis of the target material used in a two stage process for preparation of a high quality CZTSe thin film. The target material consisting of a mixture of CuSe and ZnSn alloy was synthesized, providing a quality CZTSe precursor layer for highly efficient CZTSe thin film solar cells. The CZTSe thin film can be obtained by annealing the precursor layers through a 30 min selenization process under a selenium atmosphere at 550 °C.

Realizing omnidirectional light harvesting by employing hierarchical architecture for dye sensitized solar cells.

To improve the omnidirectional light-harvesting in dye-sensitized solar cells (DSSCs), here we present a dandelion-like structure composed of ZnO hemispherical shells and nanorods. Uniformly distributed hemispherical shells effectively suppress the reflection over the broadband region at incident angles up to 60°, greatly improving the optical absorption of the DSSCs. In addition, modulating the length of the ZnO nanorods controls the omnidirectional characteristics of DSSCs.

Efficiency Enhancement of Dye-Sensitized Solar Cells' Performance with ZnO Nanorods Grown by Low-Temperature Hydrothermal Reaction.

In this study, aligned zinc oxide (ZnO) nanorods (NRs) with various lengths (1.5-5 µm) were deposited on ZnO:Al (AZO)-coated glass substrates by using a solution phase deposition method; these NRs were prepared for application as working electrodes to increase the photovoltaic conversion efficiency of solar cells. The results were observed in detail by using X-ray diffraction, field-emission scanning electron microscopy, UV-visible spectrophotometry, electrochemical impedance spectroscopy, incident photo-to-current conversion efficiency, and solar simulation.

Interfacial atomic structure analysis at sub-angstrom resolution using aberration-corrected STEM.

The atomic structure of a SiGe/Si epitaxial interface grown via molecular beam epitaxy on a single crystal silicon substrate was investigated using an aberration-corrected scanning transmittance electron microscope equipped with a high-angle annular dark-field detector and an energy-dispersive spectrometer. The accuracy required for compensation of the various residual aberration coefficients to achieve sub-angstrom resolution with the electron optics system was also evaluated. It was found that the interfacial layer was composed of a silicon single crystal, connected coherently to epitaxial SiGe nanolaminates.

Growth and characterization of Cu(In,Ga)Se2 thin films by nanosecond and femtosecond pulsed laser deposition.

In this work, CuIn1 - x Ga x Se2 (CIGS) thin films were prepared by nanosecond (ns)- and femtosecond (fs)-pulsed laser deposition (PLD) processes. Different film growth mechanisms were discussed in perspective of the laser-produced plasmas and crystal structures. The fs-PLD has successfully improved the inherent flaws, Cu2 - x Se, and air voids ubiquitously observed in ns-PLD-derived CIGS thin films.

Improved dye-sensitized solar cell with a ZnO nanotree photoanode by hydrothermal method.

This study investigated the influence of ZnO nanostructures on dye adsorption to increase the photovoltaic conversion efficiency of solar cells. ZnO nanostructures were grown in both tree-like and nanorod (NR) arrays on an AZO/FTO film structure by using a hydrothermal method. The results were observed in detail using X-ray diffraction, field-emission scanning electron microscopy (FE-SEM), UV-visible spectrophotometry, electrochemical impedance spectroscopy, and solar simulation.

Flexible-textured polydimethylsiloxane antireflection structure for enhancing omnidirectional photovoltaic performance of Cu(In,Ga)Se2 solar cells.

Because of the Sun's movement across the sky, broadband and omnidirectional light harvesting is a major development in photovoltaic technology. This study reports the fabrication and characterization of flexible-textured polydimethylsiloxane (PDMS) film on Cu(In,Ga)Se2 (CIGS) solar cells, which is one of the simplest and cheapest peel-off processes for fabricating a three-dimensional structure. A cell containing a textured PDMS film enhanced the short-circuit current density from 22.

Stability scheme of ZnO-thin film resistive switching memory: influence of defects by controllable oxygen pressure ratio.

We report a stability scheme of resistive switching devices based on ZnO films deposited by radio frequency (RF) sputtering process at different oxygen pressure ratios. I-V measurements and statistical results indicate that the operating stability of ZnO resistive random access memory (ReRAM) devices is highly dependent on oxygen conditions. Data indicates that the ZnO film ReRAM device fabricated at 10% O2 pressure ratio exhibits the best performance.

Non-antireflective scheme for efficiency enhancement of Cu(In,Ga)Se2 nanotip array solar cells.

We present systematic works in characterization of CIGS nanotip arrays (CIGS NTRs). CIGS NTRs are obtained by a one-step ion-milling process by a direct-sputtering process of CIGS thin films (CIGS TF) without a postselenization process. At the surface of CIGS NTRs, a region extending to 100 nm in depth with a lower copper concentration compared to that of CIGS TF has been discovered.

Enhancement of light output power of GaN-based light-emitting diodes with photonic quasi-crystal patterned on p-GaN surface and n-side sidewall roughing.

In this paper, GaN-based light-emitting diodes (LEDs) with photonic quasi-crystal (PQC) structure on p-GaN surface and n-side roughing by nano-imprint lithography are fabricated and investigated. At an injection current of 20 mA, the LED with PQC structure on p-GaN surface and n-side roughing increased the light output power of the InGaN/GaN multiple quantum well LEDs by a factor of 1.42, and the wall-plug efficiency is 26% higher than the conventional GaN-based LED type.

Dandelion-shaped nanostructures for enhancing omnidirectional photovoltaic performance.

Broadband and omnidirectional light harvesting is important in photovoltaic technology because of its wide spectral range of radiation and the sun's movement. This study reports the fabrication and characterization of zinc oxide (ZnO) dandelions on Cu(In,Ga)Se2 (CIGS) solar cells. The fabrication of dandelions involves the combination of self-assembled polystyrene (PS) nanospheres and the hydrothermal method, which is one of the simplest and cheapest methods of fabricating a three-dimensional, closely packed periodic structure.

Enhanced broadband and omnidirectional performance of Cu(In,Ga)Se2 solar cells with ZnO functional nanotree arrays.

An effective approach is demonstrated for enhancing photoelectric conversion of Cu(In,Ga)Se2 (CIGS) solar cells with three-dimensional ZnO nanotree arrays. Under a simulated one-sun condition, cells with ZnO nanotree arrays enhance the short-circuit current density by 10.62%.

Observation of unusual optical transitions in thin-film Cu(In,Ga)Se2 solar cells.

In this paper, we examine photoluminescence spectra of Cu(In,Ga)Se(2) (CIGS) via temperature-dependent and power-dependent photoluminescence (PL). Donor-acceptor pair (DAP) transition, near-band-edge transition were identified by their activation energies. S-shaped displacement of peak position was observed and was attributed to carrier confinement caused by potential fluctuation.

Observation of unusual optical transitions in thin-film Cu(In,Ga)Se2 solar cells.

In this paper, we examine photoluminescence spectra of Cu(In,Ga)Se(2) (CIGS) via temperature-dependent and power-dependent photoluminescence (PL). Donor-acceptor pair (DAP) transition, near-band-edge transition were identified by their activation energies. S-shaped displacement of peak position was observed and was attributed to carrier confinement caused by potential fluctuation.

Study of InN epitaxial films and nanorods grown on GaN template by RF-MOMBE.

This paper reports on high-quality InN materials prepared on a GaN template using radio-frequency metalorganic molecular beam epitaxy. We also discuss the structural and electro-optical properties of InN nanorods/films. The X-ray diffraction peaks of InN(0002) and InN(0004) were identified from their spectra, indicating that the (0001)-oriented hexagonal InN was epitaxially grown on the GaN template.

Study of surface morphology control and investigation of hexagonal indium nitride nanorods grown on GaN/sapphire substrate.

Heteroepitaxial growth of metal-catalyst-free indium nitride (InN) nanorods on GaN/sapphire substrates by radio-frequency metal-organic molecular beam epitaxy (RF-MOMBE) system was investigated. We found that different N/In flow ratios together with the growth temperatures greatly influenced the surface morphology of InN nanorods and their structural properties. The InN nanorods have been characterized in detail using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM).