7/22/2007

more heavy metals?

This isn't another post about metal bands, it's a celebration of my closet platinum acetylide fetish.[1] If you've been following CBC for a while, you already know that Excimer is much more friendly with organometallics and polymers than I am, but as with anything else, I'll make exceptions. Clearly I'm already OK with platinum. And apparently I'll read damn near anything on solar cells...So this brings us to a nifty little paper in Nature Materials.


One issue with these metallapolymers is that most of them to date have wide-ish bandgaps. While it's nice to be able to absorb lots of blue light, sunlight...isn't all blue. So crazy-wide bandgaps are not terribly useful if you're looking to take advantage of all the red and infrared light in the solar spectrum.



This brings us to the paper.[2] Apparently the donor-acceptor interactions between the cute little ring system and the icky (but tolerable because it is platinum) metal lead to a lower bandgap.[3] The weird thing about the compounds described here is that, unlike the other platinum-stuffed organic semiconductors out there, there's no emission from the triplet state. Usually, the heavy metal facilitates intersystem crossing between excited singlet state and triplet state.[4] Not in this case--the triplet energy is too low. This is explained here.


As far as device characteristics go, well, I'm assuming you can read, and I gave you the DOI.[5] The mobilities they give are less than impressive, but the power conversion efficiency for the best device was almost 5%.[6] There. That is your motivation to go and read about it. We will have a quiz tomorrow (kidding).

Added bonus: pretty colors! The authors happen to mention that the lovely polymer pictured above is purple and solvatochromic.

[1] I really can't write any further without telling you that Kirk Schanze is an absolutely kick-ass speaker. Said fetish is entirely his fault. If you see his name on a list of seminar speakers, you need to be there. I promise that everything he says will make sense and that you will not fall asleep.
[2] Blah blah blah I'm tired of writing lit posts. Three more weeks until I can start posting pictures of brightly colored compounds, guys. Start counting down the days...
[3] I have absolutely no idea how this works.
[4] ISC is "forbidden" by selection rules. "Forbidden" here carries similar weight to "speeding is forbidden," meaning that it isn't SUPPOSED to happen, but (as when driving where there are no cops) sometimes it does anyway.
[5] IF you are actually interested in those things. Since most readers are less than thrilled with device posts, this bit of blagging is solely intended to show off a nifty new compound.
[6] If devices made from MY compounds showed that kind of efficiency, you might see me skipping for the next few days. But...let's not go into that, since the only numbers I have for my stuff are so low I've blocked them out (as to avoid crying a little). This just means the engineers need to get to work and optimize everything to death...[7]
[7] You may have noticed that the footnotes to this post are almost as long as the post itself.
EDITED TO ADD: As Excimer has pointed out, I apparently can't count to four. Sad, isn't it?

13 comments:

Excimer said...

lol, yep, half this post was footnotes. well done.

Excimer said...

also, it's PBu3 ligands on those platinums.

Kyle Finchsigmate said...

Yonder phosphorus is cationic!

In other news - you can talk about dyes and polymers and you'll always have my attention.

Ψ*Ψ said...

Wow. I really screwed THAT one up, didn't I? In my defense, I was kinda rushed writing it.
I'll fix it...

Chemgeek said...

I don't dislike these posts, but I do look forward to pictures of brightly colored compounds. It brings me back to my porphyrin days.

Ψ*Ψ said...

I don't normally dislike writing lit posts. It's very useful for anyone who's learning how to skim a paper quickly without missing any important bits. It's also motivation to keep up with reading and sometimes a decent forum for discussion.
I just hate that I'm pretty much only writing lit posts this summer. So little of what I'm doing in the lab this summer is really cameraworthy. I could bring out some older photos, but I'd rather just wait until August and show off some new and awesome things then.

Felix said...

wouldn't the coordination of Pt be tetragonal planar because it has 16 electrons (10 from Pt, 2*1 from C, 2*2 from P)? (just trying to keep my complex chemistry up)

Excimer said...

yep. Pt(II) is d8 which prefers planar geometries. I bet that would have made for an awkward drawing, though.

Ψ*Ψ said...

Yeah, the FUBAR bond angles for the Pt are all just bad drawing on my part.

Hap said...

I take it that platinum acetylides don't go boom like copper acetylides - otherwise, you would get a lot more energy than it absorbed from the sun (at least for a moment)...

Ψ*Ψ said...

I'm assuming there was no BOOM. "Both metal compounds are
thermally and air stable and soluble in common chlorinated
hydrocarbons and toluene."
The word stable is generally not associated with BOOM. :)

Hap said...

Sorry.

Ψ*Ψ said...

Why are you apologising? It was a legitimate question...I was just being sarcastic...