Geometrically asymmetric BC₃ monolayer as a thermal diode: a molecular dynamics study

In this study, we employ non-equilibrium molecular dynamics simulations to investigate the unique thermal transport properties of an asymmetric BC 3 monolayer. We demonstrate the existence of infinite thermal rectification, wherein heat flows preferentially in one direction with complete suppression in the reverse, mimicking the behavior of an electrical diode. This phenomenon is attributed to the negative thermal conductivity that arises below a critical temperature difference, referred to as the transition point, where the heat counterintuitively flows from the cold reservoir to the hot one. Furthermore, the system exhibits a spontaneous heat current, allowing persistent heat flow even in the absence of an applied temperature gradient. These remarkable behaviors suggest promising applications in passive cooling, fuel-free refrigeration, and thermal logic devices. We further analyze the impact of geometric and thermal parameters, including length, width, and temperature, on the system’s heat conduction and rectification performance. To explain the underlying mechanisms, we propose an analytical model based solely on geometric asymmetry, which shows excellent agreement with our simulation results. Overall, our findings establish the BC 3 monolayer as a promising platform for efficient nanoscale thermal control.