Is there a way to build an OFET at home?
(low tech, no deep vacuum and plasma, without toxic/hard to dispose chemicals)
What can be the minimum budget for that?
While conductive polymers are pretty cheap and easy to buy, prices for semiconductors like p3ht looks like a bit high for a 'just for fun' project.
Is there a way to build an OFET at home?
You might have to do a lot of work and have some chemistry experience. This paper [Flexible and printed organic transistors: From materials to integrated circuits] describes how to print transistors with an inkjet printer (you might also be able to draw them to some extent).
Although the mobility and current on/off ratio are typically below 0.1 cm2/(V⋅s) and below 106, respectively, these previous reports expected a possibility of solution-processed or printed OTFT devices and printed integrated circuits which can be fabricated without vacuum deposition and photolithography process.
Source: Flexible and printed organic transistors: From materials to integrated circuits
You would first have to synthesize or purchase the organic chemicals (be careful some of them are toxic, but not all, some cannot be exposed to air). But yeah, if your a chemist and you don't mind failing dozens of times then you might be able to replicate the results.
Source: Flexible and printed organic transistors: From materials to integrated circuits
Section 2.3 and 3.1 will probably be the most useful read. Most of the chemicals are fairly expensive at 300-600$ for 100g or 250g. Then you also need conductive inks which are even more expensive.
The operating principle of an OFET is almost the same as that of a MOSFET, the main difference being the type of semiconductor, which is organic. Some of these organic semiconductors (such as conductive polymers) are readily available and not too expensive, but the manufacture of an OFET (as well as a "simple" MOSFET) would require process steps involving machines such as vacuum pumps or plasma etching.
Even if the size of a homemade OFET were to be larger than a "normal" OFET, a high degree of cleanliness would be required as impurities or other defects could greatly degrade the performance of a device.
