What is a solar cell?
Solar cells, also called photovoltaic (PV) cells by scientists, convert sunlight directly into electricity. PV gets its name from the process of converting light (photons) to electricity (voltage), which is called the PV effect. The PV effect was discovered in 1954, when scientists at Bell Telephone discovered that silicon (an element found in sand) created an electric charge when exposed to sunlight. Soon solar cells were being used to power space satellites and smaller items like calculators and watches.
Traditional solar cells are made from silicon, are usually flat-plate, and generally are the most efficient. Second-generation solar cells are called thin-film solar cells because they are made from amorphous silicon or nonsilicon materials such as cadmium telluride. Thin film solar cells use layers of semiconductor materials only a few micrometers thick. Because of their flexibility, thin film solar cells can double as rooftop shingles and tiles, building facades, or the glazing for skylights. Third-generation solar cells are being made from a variety of new materials besides silicon, including solar inks using conventional printing press technologies, solar dyes, and conductive plastics. Some new solar cells use plastic lenses or mirrors to concentrate sunlight onto a very small piece of high efficiency PV material. The PV material is more expensive, but because so little is needed, these systems are becoming cost effective for use by utilities and industry. However, because the lenses must be pointed at the sun, the use of concentrating collectors is limited to the sunniest parts of the country.


My works
I study the integration of plasmonic nanostructures with solar cells. Plasmonic nanostructures can offer at least three ways of reducing the physical thickness of the photovoltaic absorber layers while keeping their optical thickness constant. First, metallic nanoparticles can be used as subwavelength scattering elements to couple and trap freely propagating plane waves from the Sun into an absorbing semiconductor thin film, by folding the light into a thin absorber layer (Fig. 2a). Second, metallic nanoparticles can be used as subwavelength antennas in which the plasmonic near-field is coupled to the semiconductor, increasing its effective absorption cross-section (Fig. 2b). Third, a corrugated metallic film on the back surface of a thin photovoltaic absorber layer can couple sunlight into SPP modes supported at the metal/semiconductor interface as well as guided modes in the semiconductor slab, whereupon the light is converted to photocarriers in the semiconductor (Fig. 2c).
As will be discussed in detail in the next section, these three light-trapping techniques may allow considerable shrinkage (possibly 10- to 100-fold) of the photovoltaic layer thickness, while keeping the optical absorption (and thus efficiency) constant.



Expert in
Experimenttal



Simulation
PVsyst is designed to be used by architects, engineer, and researchers. It is also a very useful educative tool. It includes a detailed contextual Help menu that explains the procedures and models that are used, and offers a user-freindly approach with guide to develop a project. PVsyst is able to import meteo data from many different sources, as well as personal data.

RETScreen is a Clean Energy Management Software system for energy efficiency, renewable energy and cogeneration project feasibility analysis as well as ongoing energy performance analysis.

Lumerical helps designers tackle challenging design goals and meet deadlines. It has pioneered breakthrough simulation technologies that help bring new photonic product concepts to life. Lumerical envisions a future where nanoscale photonic devices are pervasive.

SCAPS (Solar Cell Capacitance Simulator) is a one dimensional solar cell simulation program. It was originally developed for cell structures of the CuInSe2 and the CdTe family. Recent developments make the programme now also applicable to crystalline solar cells (Si and GaAs family) and amorphous cells (a-Si and micromorphous Si).

AFORS-HET is a numerical computer simulation program for modeling heterojunction solar cells and measurements, developed at Helmholtz Zentrum Berlin.
Solar cells
Solar Star is a 579 MW-AC photovoltaic power station near Rosamond, California.
High Efficiency LG NeON™2 Module Cells: 6x10 Module efficiency 19.5%.
With solar energy, Freiburg is now famous as a Green City.
From solar cells to a PV system.
Operaiotn of a solar cell under illumination.
Structure of a silicon solar cell.