Tunable spin electronic and thermoelectric properties in twisted triangulene π-dimer junctions

In this work, we investigate the electronic properties and thermoelectric performance of triangulene pi-dimer junctions with the twist angle from 0 degrees to 60 degrees by using first-principles calculations in combination with a non-equilibrium Green's function method. It is found that the triangulene pi-dimer can be transformed between nonmagnetic state and antiferromagnetic or ferromagnetic state by varying the twist angle. The reason is that the relative rotation between the monomers weakens the overlap of two single occupied molecular orbital. More importantly, our theoretical analysis shows that the ferromagnetic states of the triangulene pi-dimer junctions at the twist angle of 20 degrees, 30 degrees, and 60 degrees have outstanding thermoelectric performance. The corresponding ZT value is as high as around 6, which is mainly contributed from the spin splitting nature. This work is instructive to improve the thermoelectric properties of pi-stacking molecular junctions or organic polymers.

Automated summary

This study investigates the electronic properties and thermoelectric performance of triangulene pi-dimer junctions with varying twist angles through first-principles calculations. It is found that the relative rotation between monomers can lead to different magnetic states, with outstanding thermoelectric performance observed at specific twist angles. The high ZT value of around 6 in ferromagnetic states is mainly attributed to spin splitting, indicating potential for improving thermoelectric properties in pi-stacking molecular junctions or organic polymers.