Antireflective and Radiation Resistant ZnO Thin Films for the Efficiency Enhancement of GaAs Photovoltaics

Abstract

In this paper, zinc oxide ͑ZnO͒ thin films as an antireflective ͑AR͒ coating layer have been successfully fabricated on GaAs solar cells by the sol-gel method. ZnO films were prepared chemically by spin coating the gel with an aqueous solution of zinc acetate and ethanolamine. The current-voltage measurements of the solar cells confirmed the increase of the short-circuit current induced by the AR effect. The open-circuit voltage and fill factor were also improved by the surface passivation. As a result, the conversion efficiency of the cells without an AR coating ͑8.2%͒ was significantly enhanced to 13.6%. The results indicate that the chemical deposition of ZnO was effective for the AR coating of GaAs solar cells. Additionally, we demonstrate that the cells coated with radiation resistant ZnO films exhibit less efficiency decay than the devices without such treatment. Under the maximum proton fluence of 10 13 cm −2 , the conversion efficiency decay was reduced to 69.8%, while the solar cells without ZnO films showed an efficiency decay of 83.1%.

Improved Negative Bias Stress Stability of IZO Thin Film Transistors via Post-Vacuum Annealing of Solution Method

“…27 The ratio of peak areas O I /O total rose from 30.1% (for as-prepared IZO) to 45.5% and 50.1% (for 250 • C and 350 • C vacuum-annealed IZO films, respectively), indicating relatively high oxide lattice content and fewer oxygen-related defects and thus enhanced TFT performance. 10,16,28 The decrease in the number of oxygen-related defects could be related to the reduction in film porosity and the larger number of Zn and In atoms bound to oxygen atoms. These results show that the IZO film became denser after the post-annealing process, and thus had fewer oxygen vacancies.…”

“…14,15 The sol-gel method was chosen for the current work due to its many advantages, such as simplicity, low cost, and high throughput. [16][17][18] Although the sol-gel-processed TFTs can perform as well as vacuum-processed metal-oxide TFTs, it is challenging to obtain films with high degrees of condensation for use in TFTs, whose performance is influenced by the film porosity, impurities, and unnecessary carbon groups. 19,20 Rim et al recently investigated how high-pressure annealing affects the thermodynamics that occur in the formation of solution-processed oxide films with various gas atmospheres.…”

Effects of PEG1000 and Sol Concentration on the Structural and Optical Properties of Sol–Gel ZnO Porous Thin Films

“…Antireflection (AR) coatings have many great applications in optoelectronic devices that require maximum light transmission such as solar cells and camera lenses [ 1 , 2 ]. They can obviously reduce incident light reflection of the material surface and increase transmission.…”

UV-Ozone Process for Film Densification of Solution-Processed InGaZnO Thin-Film Transistors

“…Solution-processed inorganic semiconductors have been investigated for the fabrication of large-area electronics [3], [4]. The wet chemical sol-gel method have many advantages such as simplicity, high throughput, ability to produce high-performance low-cost electronics [5]- [7]. However, such methods typically require a high-temperature annealing step, which results in film porosity, defects, and residues, which influence the metal oxide formation.…”