Back when we looked at organic semiconductors, CMOS was a hard thing to do because the standard organic materials were generally p-type. Meaning that organic circuits would consume more power.
A couple of news items have come out recently describing a mysterious material developed by Polyera. The first release was from Norwegian company Thinfilms; they had worked with PARC on developing organic CMOS technology and ultimately announced printed addressable memories that incorporated the Polyera material. “Printable” in this case refers to a so-called “gravure” process, which means it uses a roller (not an inkjet or some other writing means).
The second announcement was from Imec, who announced a higher-efficiency solar cell that incorporated a Polyera “proprietary” material.
I had seen some information on the Thinfilm work even before their Polyera announcement, and I checked in with them. And they didn’t have anything to say until the collaboration with Polyera was officially announced. Once they had outed Polyera, I checked with Polyera to confirm that they had developed an n-type printable material and, if so, what it was.
They confirmed that they did have an n-type material. And as to what it is? It’s this novel material they call “proprietary.” Yeah, they’re being coy. They say that they have “… a few different classes of n-type semiconductor materials, both polymer and small molecule.” They also provided this bit of clueage: “… we develop materials (which are often powders), and then formulate them into inks to enable them to be applied. A given powder can have many different formulations depending on lots of different things (the deposition method, other materials in the device stack, etc.)” In fact, the specific formulation they use for ThinFilm will be exclusive to ThinFilm.
In general, their website lists a number of p-type and n-type materials, mostly as powder, a couple as inkjet, and one that’s “spincoatable.”
However, when I asked whether the solar cell material was the same (more or less), they responded that, “…our OPV and OTFT materials are quite distinct from each other.” And again we’re left wondering about the details. But the work that they did with imec related to a “bulk heterojunction” formulation. This is where n- and p-type materials are mixed together and deposited, and which then separate into distinct p and n regions closely separated. The idea here is that, once a photon has created an electron/hole pair (an exciton), you need a pn junction close by to separate the two so they don’t simply recombine. That’s what these closely-spaced n and p islands try to accomplish. And Polyera is somewhere in that blend.