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?