Energetic and entropic issues are theoretically addressed in quantum optoelectronic nanodevices. We rely on the nonequilibrium Green's function methodology to provide a framework which combines optoelectronics and thermodynamics in a unified picture of energy conversion for nanoscaled optoelectronics. Indeed, we follow the self-consistent Born approximation to derive the formal expressions of energy and entropy currents flowing inside a nanodevice only interacting with light. These expressions are numerically evaluated in a quantum-dot based nanodevice, where verification of the second law of thermodynamics raises questioning about the system model. We here put the focus on the spontaneous emission energy current to discuss the question.