Since EdgarAllan Poe's "The Tell-Tale Heart" exemplifies several of Poe's characteristic techniques, it can be used as a "springboard" for a research paper on one or two of these techniques. For instance, a research paper could examine a technique of Poe's known as arabesque. This is a term that Poe named his method of developing details in a fantastical manner, which is often a distorted or mangled vision of reality. Sometimes this is termed grotesque; the arabesque/grotesque is used to allow the reader to understand the terror of the character(s).
Another technique Poe employs in many of his works that is exemplified in "The Tell-Tale Heart" is the use of the unreliable narrator. Again, Poe creates an immediate terror or horror by having the point of view of his narrative come from the disturbed mind of a first person point of view. Certainly, the use of this type of narrator contributes greatly to the gothic tone of his tales.
So, you may wish to examine closely techniques that Poe uses which make his stories uniquely terrifying. Using "The Tell-Tale Heart" and other stories as illustration of these points will provide supporting details to the research that you make.