What is a great PhD Dissertation?

First thing which should be kept in mind while opting for research is that the area and the topic you’ll choose should vast and it should open doors for future research.
It should always leave an impact on the readers and the evaluators. They should get a question in their minds that, “When will somebody else will pick this topic of research?”
It should also give an impact that the research has really changed a few things or the problem you chose, really need to be solved. Try to end your research with a question mark so the people look forward to more.
In case your topic is too technical then you should try to make it a little accessible and understandable to others.. Keeping in mind all these points will surely help you get a great dissertation.