Question about Research interests

[SetV]

I plan on applying to grad school this upcoming Fall. I've been doing research in thermoelectrics on the nanoscale. The problem I'm facing is that not many people do research in thermoelectrics. Nonetheless I'm still interested in doing research in nanoelectronics/nanotechnology as I like the physics aspect of electrical engineering.

Would it look weird in the adcom's eyes if I say I did research in thermoelectrics, but for graduate school I'd like to do research in e.g. compound semiconductors, graphene, etc. Also, is it OK that I haven't done any research in these subfields yet? So should I have research experience in those subfields to back up my research interests. Or is it OK to say I've done research in thermoelectrics, I've taken several physics classes and although I won't be doing thermoelectrics in grad school, I want to pursue research in nanoelectronics?

Has anyone else had similar experiences, i.e. did research as a UG but planning on doing something different as a graduate student?