Thermophotonics (TPX) is a technology close to thermophotovoltaics (TPV), where a heated light-emitting diode (LED) is used as the active thermal emitter of the system. It allows to tune the heat flux, by means of electroluminescence, to a spectral range matching better the gap of a photovoltaic cell. The concept is extended to near-field thermophotonics (NF-TPX), where enhanced energy conversion is due to both electric control and wave tunneling. We perform a thorough numerical analysis of a GaAs based NF-TPX device, by coupling a near-field radiative heat transfer solver based on fluctuational electrodynamics with an algorithm based on a simplified version of the drift-diffusion equations in 1D. Through the investigation of the emission and absorption profiles in the LED and the photovoltaic (PV) cell, and the scrutiny of the impact of key parameters on the performance of the device, we highlight the necessity to model precisely the charge transport in both the LED and the PV cell for obtaining accurate results. We also demonstrate that the performance obtained with this algorithm can approach idealized cases for improved devices. For the considered simplified architecture and 300 K temperature difference, we find a power density output of 3 kW.m−2 , underlining the potential for waste heat harvesting close to ambient temperature.