Provided are methods of fabricating photodetectors based on heterostructures comprising graphene and mercury chalcogenide, e.g., HgTe, quantum dots. Embodiments of the methods are able to provide photodetectors that can detect MWIR light, e.g., greater than 3 mm at room temperature with responsivities R* of at least 104 A/W and detectivities D* of at least 1011 Jones. Thus, the present photodetectors outperform existing MWIR photodetectors without the need for cooling. The photodetectors themselves are also encompassed.