I have no experience in chemistry, but maybe some general ideas about industry apply?
Presently Oleds are fashionable, but nobody on Earth can predict for how long. Maybe we'll see them everywhere, maybe they'll disappear quickly. Even if they succeed, at some point the industry will consider research as ended, and in some future an other technology, which we can't foresee, will replace them. Think at the Cdrom for instance: huge research effort first, then some companies (but not all) made good money with them, and meanwhile they're disappearing, replaced by Usb stick and other supports that we couldn't imagine back then.
So don't imagine a career in the research for Oled. At some unpredictable point, you'll have to do something else.
Neither can we predict which company in which country will live from Oleds, if any. 30 years ago, clever future predictors told "Europeans shall make silicon because of its brain value, and buy machines from low labour cost Chinese". Presently, the French sell cheese to the Chinese, the Germans and Swiss sell them machines, and all buy the silicon chips from China.
So my suggestion would be: make Oleds right now if you like it, but be ready to do something else as the wind turns. Try to be as multi-purpose as a Swiss army knife, within chemistry and possibly outside. And learn foreign languages.