Silica Microspheres for Economical Advanced Solar Applications

Maha M Khayyat

doi:10.3390/cryst11111409

Abstract

Solar cells made of silicon nanowires (Si-NWs) have several potential benefits over conventional bulk Si ones or thin-film devices related primarily to light absorption and cost reduction. Controlling the position of Si-NWs without lithography using silica microspheres is indeed an economical approach. Moreover, replacing the glass sheets with polycarbonates is an added advantage. This study employed the Nanoscale Chemical Templating (NCT) technique in growing Si-NWs seeded with Al. The growth was undertaken at the Chemical Vapor Deposition (CVD) reactor via the original growth process of vapor–liquid–solid (VLS). The bottom-up grown nanowires were doped with aluminum (Al) throughout the growth process, and then the p–n junctions were formed with descent efficiency. Further work is required to optimize the growth of Si-NWs between the spun microspheres based on the growth parameters including etching time, which should lead to more efficient PV cells.

Highlights

Advanced Solar Applications.Conventional 3D crystal growth requires only two phases; nanowires grow in three-phase systems
The vapor–liquid–solid (VLS) mechanism is based on systems that combine three phases: a vapor that supplies the materials for crystal growth, a liquid droplet to seed the growth, and the solid crystal
The combination of the Nanoscale Chemical Templating (NCT) technique along with silica microspheres is an economic approach, as it requires fewer steps compared to conventional patterning approaches, not requiring lift off of a metal layer or the removal of the mask

Summary

Introduction

Advanced Solar Applications.Conventional 3D crystal growth requires only two phases; nanowires grow in three-phase systems. One-dimensional crystal (NWs) growth occurs when the growth rate at the interface between the liquid phase and the solid crystal is higher than the growth rate at the interface between the vapor/solid phase boundary. Vertical NWs made of silicon substrate are of great interest because they would allow for ultimate light trapping and distinguished charge carriers’ separation for solar cell applications. They could achieve, in principle, better efficiency than thin-film planar cells, with the added merits of minimal use of materials and much lower process cost [1]

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