Image credit www.devicedaily.com

Here’s how solar cells work at the most basic level:  photons (units of light) hit the surface of the cells and the light energy is quickly absorbed by the semiconductor material.  The incoming energy knocks electrons loose from the silicon, and when that happens it’s as close to spring break in Fort Lauderdale as it gets at the atomic level.  To keep all the electrons from spending the night sobering up in the local jail and having to make teary calls home their parents, two metal contacts (one at the top and one at the bottom of each cell) create an electric field that forces all the crazy sunburned drunken electrons to line up and form a current that allows us to put them to good use (Source: HowStuffWorks). 

It’s not as easy as you might think to free electrons from their cozy little orbits, and today’s best solar cells are not as efficient as one might hope: they convert only “15 to 20 percent of the energy in sunlight into electricity” (Bourzac).  We’ve been using way too much silicon to generate not enough electricity for much too much money for far too long.  But that could change because a new photovoltaic material has been developed that performs just as well as current solar cells yet uses only one percent of the material to do it!

Image credit M. Kelzenberg

Researchers at Caltech led by professor of applied physics and materials science Harry Atwater have developed a “flexible array of light-absorbing silicon microwires and light-reflecting metal nanoparticles embedded in a polymer” (Bourzac).  The idea is that the new material traps incoming photons of light and keeps them bouncing around dislodging electrons for longer periods of time – generating more electricity from less material.  Highly reflective alumina nanoparticles are mixed with a rubbery polymer, forming a coating which is applied to arrays of anti-reflective silicon microwires “grown” from gas on the surface of a reusable template.  “Once the polymer sets, the entire thing can be peeled off like a sticker. Over 90 percent of the resulting material is composed of the cheap polymer, and the template can be used again and again … The material can absorb 85 percent of the sunlight that hits it, and 95 percent of the photons in this light will generate an electron” (Bourzac).

Image Credit M. Kelzenberg

Using less silicon and decreasing the complexity of the manufacturing process could mean that it will take less capital to build solar cell components and that we will be able to build them more quickly. 

WU XING:

This is a fire material because of the light-trapping.

Cited:

Bourzac, Katherine. “Material Traps Light on the Cheap.” Technology Review 02/26/10.  Accessed 03/01/10.  URL.

A few days ago I encountered Jali Zari.  Surprisingly, Jali Zari is not a bald martial arts expert with a penchant for tamarind cooler.  Jali Zari is the street name of a family of acrylic panels that made the lemon that is acrylic’s propensity to scratch into a zesty lemonade by making cuts within the panels that redirect light and shadow to form attractive patterns.  Standard panels are 8 x 4 ft by 3/4 in. thick clear acrylic with a backing film applied with a transparent adhesive (AEC world XP).  The film comes in a variety of transparent and “radiant” colors.  If you’re making room dividers, lighting, signage, wall coverings, furniture, or whatever else, you’ll be able to can cut, glue, and/or etch these panels, but don’t try to thermoform them because Jali Zari will come for you and I promise you do not want to mess with that guy.

Image courtesy AECworldXP.com

Five different versions are available but, due to the veil of mystery and enigma that surrounds Jali Zari, I can’t find any images of them.  Any help would be appreciated – please comment or contact me if you have an image I can use.

1.  Quadrato resembles a flattened honeycomb (check out my post on honeybee silk to see a honeycomb).  The pattern consists of “symmetrically stacked refractive acrylic squares with slight variations among rows.” (AEC world XP). 

2.  Triangolo is aligned in rows of light-reactive triangles redirect light and shadows in a consistent pattern (AEC world XP).

3.  Mille reflects light from every orientation because it contains many tiny slices and slashes arranged sporadically with varying lengths and depths.

4.  Cascata is also active from every viewing angle, it resembles a waterfall through randomly spaced light deflectors of varying sizes (AEC world XP).

5.  Cambia is a random composition of cuts and slashes “arranged sporadically to encourage light refraction” (AEC world XP).

WU XING:

All my polymers fit in the wood category because they share some characteristics with wood in terms of flexibility.  Jali Zari also fits in the fire category because of the dynamic quality of the light scattered by the cuts in the acrylic. 

Cited:

“Connecting with Innovation.” AECworldXP.com accessed 02/04/10.  URL.