It’s the stability of organics vs conventional inorganic materials. For organic photovoltaic cells, for example, efficiencies currently overcome those for amorphous silicon-based devices. The drawback is that you cannot use them on the top of the roof of your house to get electricity, at least not for a long time, because when exposed to the combination of heating and light, organics degrade faster , and your device loss it’s efficiency. However, OE are very important in complementary applications (the e-skin, for example, or the OLED displays , or portable photovoltaics( much lighter devices are possible). Another point is that charge mobility in organic semiconductors is inherently lower than that in the inorganic counterparts, and this means that it would not be possible to reach the performance of the most performing types of inorganics. But this is not the objective. The major objective is to complement them. In fact, some characteristics are not possible to be achieved by conventional inorganics , like transparency, lightness, low energy manufacturing (OE devices can be printed like newspapers!) Examples of benchmark organic semiconductor are polythiophenes, pentacene derivatives, etc. For the dielectrics also polysaccharides, silicone rubbers, silk fibroins and so on. You need to have something which can be easily ‘polarized ‘ We recently carried out a study were we used polymers extracted from brewers spent grains (which is a byproduct of the brewing industry) to make dielectrics for transistors