On Jun 29, 2009, at 10:54 AM, Michael Foster wrote:
The general idea of creating a structurally black surface on
silicon or other photovoltaic is a sound one, both from the point
of view of making the photovoltaic more efficient and for the
secondary effect of using the unconverted light to make heat for
storage.
What I find annoying in this article is the method of achieving
that. So we have a group of whiz-bang boys from Harvard who are
promoting a method that requires prohibitive amounts of energy to
achieve this effect, when there are much more efficient and well-
known ways of doing the same thing. I have a method of my own that
works, not just for silicon, but for metals as well. These guys
will suck up lots of venture capital because it sounds so high tech
and they're "really smart guys". Ultimately the project will die
unless a specialty niche is found for the product, but the people
involved will go on to the next technical boondoggle to waste some
more venture capital.
If I were to contact these boneheads and tell them how to do this
economically, they would ignore me completely and act like I was
something that needed scraping from the bottom of their shoes. I
speak from numerous experiences.
M.
Interesting. I've considered trying "passification" electrolysis
methods, which if done properly also can create a black or dark
surface nano-structure. I does a beautiful job on aluminum, but I
don't think aluminum oxide can be doped to provide the proper
photoelectric properties. I think electrolytic passification might
work for silicon, since electrolizing with a sodium metasilicate
solution appears to provide the ability to deposit a nano-structured
surface.
I suppose a vacuum deposition method of some kind might be feasible,
e.g. deposition of a nano-powder.
A pointed nano-surface like that shown in http://tinyurl.com/lreufb
should be highly "hydrophobic", so I expect another part of the
problem might be getting the exterior transparent conductive coating
to stick.
I think experimenting with home-brew photoelectric cells might
actually be feasible for amateurs. That is because, provided the
surface prep is done electrolytically, if the cell is prepared in a
shallow horizontal tank with a strong light above, the electrolyte
can work as the transparent surface electrode, and thus direct
(comparative) measurements of the surface photoelectric efficiency
can be taken periodically as the electrolysis proceeds. This provides
plenty of room for fine tuning the process and plenty of room for
serendipity.
Also of possible interest is experimenting with the use of cobalt
phosphate (etc.) catalyzed hydrogen production via a process similar
to that of Daniel Nocera's. A similar set-up would be useful for that
as well. I think a bromide of some kind might work well, because the
potential required for electrolysis is reduced for bromide solutions.
Best regards,
Horace Heffner
http://www.mtaonline.net/~hheffner/
