Transparent Quasi-Random Structures for Multimodal Light Trapping in Ultrathin Solar Cells with Broad Engineering Tolerance.

Waveguide modes are well-known to be a valuable light-trapping resource for absorption enhancement in solar cells. However, their scarcity in the thinnest device stacks compromises the multiresonant performance required to reach the highest efficiencies in ultrathin devices. We demonstrate that enriching the modal structure on such reduced length-scales is possible by integrating transparent semiconductor/dielectric scattering structures to the device architecture as opposed to more widely studied metallic textures.

Defect seeded remote epitaxy of GaAs films on graphene.

Remote epitaxy is an emerging materials synthesis technique which employs a 2D interface layer, often graphene, to enable the epitaxial deposition of low defect single crystal films while restricting bonding between the growth layer and the underlying substrate. This allows for the subsequent release of the epitaxial film for integration with other systems and reuse of growth substrates. This approach is applicable to material systems with an ionic component to their bonding, making it notably appealing for III-V alloys, which are a technologically important family of materials.

Designing transparent nanophotonic gratings for ultra-thin solar cells.

Integration of a rear surface nanophotonic grating can increase photocurrent in ultra-thin solar cells. Transparent gratings formed of dielectric materials and high bandgap semiconductors can offer efficient diffraction with lower parasitic absorption than more widely studied metal/dielectric equivalents. In these systems, the maximum photocurrent which can be obtained for a grating made of a given combination of materials is shown to follow a simple empirical model based on the optical constants of these materials and independent of grating dimensions.

Light management in ultra-thin solar cells: a guided optimisation approach.

The success of ever-thinner photovoltaics relies on the introduction of light management strategies to enhance the absorption of incident illumination. Tailoring these strategies to maximise the absorption of light requires optimising the complex interplay between multiple design parameters. We study this interplay with a transfer matrix method and rigorous coupled-wave analysis, within the context of waveguide modes in an ultra-thin (80 nm) GaAs solar cell.

Imaging Atomic-Scale Clustering in III-V Semiconductor Alloys.

Quaternary alloys are essential for the development of high-performance optoelectronic devices. However, immiscibility of the constituent elements can make these materials vulnerable to phase segregation, which degrades the optical and electrical properties of the solid. High-efficiency III-V photovoltaic cells are particularly sensitive to this degradation.