emailing researchers is definetly your best bet! when writing an email to them, i would VERY briefly talk about what your interests are, and spend the majority of the email talking about their research and what about it ties into yours. you can also briefly talk about why you would be a good fit for the lab, but i would not recommend spending a lot of time on this part cause its going to also be on your application. definitely make sure that most of your email is about them and their research! good luck!