So we were having this discourse on fundamental limits for energy
conversion %uh for I thought I said
and in the some other business leaders I describe you this
excellent work done by William Shockley in hun sky there
and this %uh paper they published in 1961
where the user approach up for debate about it that as though you
assess view that time when immigrants that to you
a says the Batanes the incoming and outgoing radiation at each frequency
and know that is also acquire the shocky a quite there
limit so this was %uh published by then the you know in 1961 but
they made third in a themselves which were which was fine the
back then when you know this with love the first book so
calculating this %uh find them into efficiency limit
but there needs to be corrected the in the in the
current light of things so feel that which is that they made
a which need to be corrected was that the human that the Sun and the said
how would I get back but he said they are viewing the Sun to be at a blackbody
a a
the radiation coming from the Sun is equal into a black body which is that
good a pitcher of
60 then Kevin we know that to the actual radiation which %uh comes from the Sun
it has the third and bites a the spectrum which are observed that do that
much fear
so that this that needs to be a tough critic that far
does that mean that they have the option is a a step function so I the photons
which have the energy
to a frequency greater than the energy of the band gap there completely at the
why those which have been good to night at that and you know that
to a you know I the semiconductor materials they have a
absorption goes in which it depends upon the energy so it's a not fair to
humor a step-up profile exactly as they are the only to
though it does we got in there took into account was the only one
and %uh that was out with a concerning to radiative recombination
media I know that you know there are few more fundamental
last week on them and one of them is related to
was a reexamination and other one is related to
free carrier abduction and either for a fundamental
do anything a conductor as red so that these needs to be taken into account as
well while
calculating this a if its limit for this was done by
a the Asia and yep you know it's in a paper day published a in the nineteen
eighty-four
and it's a its good as the detail you have to know which limit
in the in honor of there a paper
for this is the paper that was %uh published it was published in connection
of electron devices
in the nineteen eighty-four let me again the
is read through the read through that check so what they're saying overhead
that
that extending this study did a bad in summit at which were the first two done
by shock the end by their
in 1961 and day
%uh including this other last weekend in which I mention it is a free guided
abduction
and the OJ recombination you know that describe what they mean
and this is included in addition to the radiative recombination began
and a based on this Big Ed
limiting efficiency of like 20 9.8 percent
a4 a.m. 1.5 spectrum so instead of the blackbody radiation the
assuming the Sun to be a black body that taking this AM 1.5 %uh specter
and therefore they say that the silicon the surface
a is that banks should to benefit from other light trapping effects
so that's good to know what day I didn't do it step by step safe I'd look at
their paper the way for this thing that it was instead of
you mean that phone to be a blackbody they are the room the Sun
respective from the Sun to be equal and do with the AM 1.5 G specter
and if you do that then the efficiency in just by taking into account
only the a only the radiative recombination
you see a much higher efficiency coming up a
so you got your efficiency love close to 33 percent
if you do that and this is just by changing the spectrum from a
the idea that but expected given but thanks for
to the actors spectrum which %uh that which is up to
that as a this in 1.5 ag's spectrum
the second thing that to appease and yep you know it's a paper corrected for
was this a shock the Envoy there to the on the the option to be a step function
so that at the on that
%uh the available in so it's a %uh the frequency that to a greater than the
band gap they are after the
to immediately and %uh the frequency that %uh that are not about it but
in reality the absorption coefficient at looks as something like this
that instead of being exactly a a step function you see this
the you this guy fee this kind of a pro fight
that this the absorption coefficient it depends upon the energy of the incoming
put on
so they aren't big they took this into account
in fact if you have a foot on that show whose energy is that way close to the
band gap of silicon
then in fact in fact that have a poorer abduction go fishin
and many a times al-aziziya escape out of value semiconductor
without getting at La Plata so they took into account to I love this though they
are you'll notice that takes to
surface and this textured surface as you do
a maximize the like dropping and this is a worthy of another
re yes I described as a limit of light trapping the
in another video but they argued that to this %uh front surface it has a
reflectivity of 40
and this back surface it had a reflectivity of 01
saw the light but is reaching this %uh black surface either compatriot
afflicted of
and as you know that this sale has a finite thickness at it as a
us a which is that you need to consider it for
a if the some of the other if some of you respect him as a
escaping out so then other thing which is the
radio find them into the lost my god
which day it took into account was the the
to other last week I which is the 3 got its option
and the OG recombination saying the shock equaliser paper and that would be
a good enough to go to them that
shocks and by the took into account was a every combination
so what they said was if you have the the electrons and holes
president the only luck began to them in the city that a combination of them
which emits a foot on but that to add the additional
the the company the commission because I know you know that
two additional up the the last nigga which are fundamental to any semi
conductor
so though let me talk about this was a recommendation for
so this Oil City Commission means that to
instead of us instead of footy the
electrons and all the Rica mining and giving out that the extra energy
before done they get officially give the the extra energy
to either a a lectern which is now excited
and no it know there's this energy in the form of lattice conditions which are
out for the words
the Noel photon emitted a in this %uh process but it's a
the bar to go process where this excess energy is getting
do this to electrode and it doesn't do with this and
in the fall of 08 similarly the the electron a and who is
they can the Rica mind and they can give this extra energy to a hood
and which was subsequently knew that the back to in the following the the photons
that the that s libration
so this is a fundamental processes that was a recombination is a fundamental
process a
anything the conductor and it to its at the party the process that and what is
this
electron this whole and in this case this electoral
it similarly or hit and was one electron and
do love these hoes in this raid 0 the sordid combination
since the three but the you up by two Go process
itself to push the do in this case the
and square be and in this case where there's extra energy though given to a
hood
is proportional to do well its choir love the whole concentration multiplied
by the state electron concentration for this is the
fundamental prices that needs to be a taken into account as well
another life though mic and images I get enough for them into
is this %uh free carrier at the option so what it means that
if you have a URL if you have a incoming photons
and usually they excited electron and hole pair
but instead they can I was so excited be the free gay is that it's a and Dave
semiconductor
and you have a a lot of electrons by then taught her
so instead I love the the a into these photo an exciting the electron it would
bear
they can now get absorbed by the the free guy so this an act on that day away
this and as you know the photo and it will get excited
when subsequently this excited electron would I do without it energy in the form
of
again %uh floods so this is also fine Amanda
a phenomena the last weekend which is a
native to which other than the anything tonight demented
and %uh so that doesn't leave that to into account and
us although this though is a recombination is a is actually
a much more a much bigger
last weekend as compared to this %uh free carrier adoption
so this is nicely a show in the Investor in this supplier to our hair
from their paper the say they said a in an idea that case
your incoming light that you said the shot so good good n tuff
a fight he do going to medium for this said it which is a
as you do we have this checked saying and effectivity of the right defends her
face and effectivity of one at the back surface
sorry love that tough forty do playing do you see that
according to a according to that and I says
the 88 the recombination its a
allows you to that is a earned a point tough for me they appear
but the OG recombination the lies you do that it's actually much higher
and the last third you that as approximately
point nine davidians appear the Freak that have the option
a is also president but denied you do that that mice that's it
a Boise to media and then there the the other doesn't go
them said that you know some of it though is like this to
not get abducted will escape the said so what you get net
is a a fraction the of this the incoming
light as though what you connect as a fight a
a extracted a current and this is a
fundamental limit for that is up forty 1.1
million for this said which other take this %uh 400 micron
and so they derive to the fundamental efficiency limit for a silicon
a which is this a DJ every 10 ish give it they did I a bid to be a road queen
I'm playing 8 percent for the case of
silicon so this again this search Iran borrowing from
got big science in it does summarizes the exhaust McCatty though they've read
so if you take the achcha spectrum of
in 1.5 the shock because the limit become the
33 percent but now you have to take into account the that
I you have a rather than having a step function for your abduction
you have a finite at the option caution so you
do though does some light which escapes are the said without getting
as I and then you us that this orgy recombination which does out to be a
look
a that shares of a few more than a few percentage points out of a deficiency
and the the EJ you've no doubt which limit for
for for this a single junction the silicon-based
the Soto said as approximately rainy night at 39.8 percent to be exact
and the best practice the the best university says
actually which have been demonstrated this regard belongs to the University of
fun you start with
and this this regard as their own grief I percent
the practical limit that some additional I say they were here so
there might be a you know the deflect as a defense surface and so is the
practical limit that you can achieve a
that does silicon-based a thing attention says
as our own Dec 26 to 27 pussy