Subject: Re: 80% SOLAR MATERIAL efficiency

From: Malcolm Sanders <[email-masked]>
Date: Fri, 14 Apr 1995 19:07:34 GMT

Regarding Alvin Marks, LUMELOID and efficiency:

Here is a relevant excerpt from "Practical Photovoltaics, 3rd
edition" by Dr. Richard Komp, which will be appearing in print in a
month or two.  It is particularly useful to be very sure what you
mean, when you use the term, "efficiency" in connection with
photovoltaic devices

-Malcolm Sanders.

The following is from "Practical Photovoltaics, 3rd Edition" by
Richard Komp, excerpted with permission from the author.
------

        Recently, Alvin Marks, the inventer of 3-D movies, has been
working on a new concept in an organic solar cell.  He has been
taking the thin polarizing plastic films used in those cheap paper
glasses we wore to watch the movies, and changing the formulation of
the linear polymers to make the films electrically conducting.  The
idea is: the films absorb virtually all the light of a particular
polarization and produce free electrons to be captured at an
electrode strip on the film.  Two films with crossed polarization
will absorb all the incoming light, leading to a high quantum
efficiency.
        Alvin Marks started a small company in Western Mass. called
Phototherm, Inc to work on this idea. (Apparently he now uses the
name Advanced Research Development, Inc. as his working company with
an unclear connection to Phototherm.)  His basic idea is feasible
from a scientific point of view and, with the help of a couple of
small grants and some research assistance from Argonne National
Labs, he has succeed in producing the conductive polarizing polymer
films but has seen no photovoltaic effect yet.  The tricky steps
seem to be those of incorporating the necessary diode junction into
the polymer chains using charge transfer dyes, and arranging a path
for the electrons to get to the collecting electrodes without
shorting out the microcells.
        Another embodiment of his idea, using microelectronics
techniques to fabricate the multitude of submicron sized dipoles
onto an inorganic substrate, is being tried at the nearby University
of Lowell.  This system should produce a working device but will
probably be too expensive for ordinary use.
        Alvin Marks has been claiming very low cost and high
efficiency for his LUMILOID polymer solar cell.  While the plastic
film cells will probably be inexpensive to produce, he has confused
quantum efficiency, which can be very high for organic dye
molecules, with device energy efficiency, which will probably remain
low.  However, an energy efficiency of only 5% would be
commercially useful in a simple device.
        Care must be taken to distinguish between quantum
efficiency, which is the number of current electrons created and
delivered to the front contacts (of a solar cell) compared to the
number of photons falling on the solar cell; and energy efficiency,
which is the total electrical power output compared to the input
power flux of light energy.  For example, a good crystalline silicon
cell may have a quantum efficiency of 85% but a total energy
efficiency of 19% because the high energy blue light photons only
produce the same energy in electrons as the infrared photons do.

Re: 80% SOLAR MATERIAL efficiency