Performance of Ultrathin Silicon Solar Microcells with Nanostructures of Relief Formed by Soft Imprint Lithography for Broad Band Absorption Enhancement

Abstract

Recently developed classes of monocrystalline silicon solar microcells can be assembled into modules with characteristics (i.e., mechanically flexible forms, compact concentrator designs, and high-voltage outputs) that would be impossible to achieve using conventional, wafer-based approaches. This paper presents experimental and computational studies of the optics of light absorption in ultrathin microcells that include nanoscale features of relief on their surfaces, formed by soft imprint lithography. Measurements on working devices with designs optimized for broad band trapping of incident light indicate good efficiencies in energy production even at thicknesses of just a few micrometers. These outcomes are relevant not only to the microcell technology described here but also to other photovoltaic systems that benefit from thin construction and efficient materials utilization.

Light Trapping in Plasmonic Solar Cells

“…Over the time frame of this thesis, light trapping with nanophotonic structures has increased in popularity, with the demonstration of solar cells including nanophotonic structures such as nanowires, nanocones, photonic crystals, coaxial structures, nanoparticles, and gratings [18,19,20,21,22,23,24,25,26,27,28,29]. Recent papers have also sought to quantify the upper limit to light trapping in the wave optics limit; Chapter 5 describes one method for comparing nanophotonic structures to the ray-optics ergodic limit [30,31,32].…”

“…Using To date, light trapping geometries based on nanowires, nanocones, photonic crystals, nanoparticles, gratings, and random textures have been demonstrated [18,19,20,21,22,23,24,25,26,27,28,29,116,117,131,135,136]. While many researchers have demonstrated increased photocurrent due to scattering-mediated light trapping, the role of spatial correlations and surface topography of random or periodic arrange-ments of the scattering nanostructures has remained unclear.…”

Hut-like pillar array Si solar cells

“…In combination with the dominance of the surface effects due to the high surface-to-volume ratio (Dan et al, 2011;Chang et al, 1993). This may worsen the electrical performance of the solar cell regardless how good the optical performance is (Dan et al, 2011;Green, 1982;Toor et al, 2011;Shir et al, 2010). Furthermore, high levels of surface recombination can lead to a short life span for the material.…”

Management of light absorption in extraordinary optical transmission based ultra-thin-film tandem solar cells

“…Till date, a number of structures have been used that are capable of coupling the incident light to surface modes such as surface plasmon polaritons (SPPs) and localized surface plasmons (LSPs), and different photonic modes so that light can be confined in a sub-wavelength dimensional structure. The structures mainly use nano-structures and gratings of metal and dielectric material in different layers of solar cells [3][4][5][6][7][8][9][10][11][12][13][14][15].…”