Graphene, a single atomic membrane formed by carbon atoms, is an interesting potential optoelectronic material with unusual electronic, optical, and thermal properties. Although tremendous progress has been made towards graphene-based optoelectronics, there is a lack of understanding of the underlying physics of photocurrent generation and demonstration of hybrid graphene optoelectronics. I will first talk about the demonstration of the photo-thermoelectric effect dominating the photocurrent generation at a graphene single-bilayer interface junction. Then I will present our recent measurements of hot carrier dynamics in graphene PN junction. I will conclude with the integrated graphene nanoconstriction-Au break junction plasmonics, which demonstrates a plasmonic photodetector at ~ nm scale.