Tunable thermoelectric performance in metal-organic framework Ni(BDC) studied by first principles

Metal-organic frameworks (MOFs) have unique advantages in thermoelectric applications due to their low lattice thermal conductivity. However, the low electrical conductivity limits their thermoelectric performance. In this work, we report a strategy to improve the electrical conductivity of MOFs by infiltrating pillar molecules into the layered MOFs. First principles studies indicate that after the Ni(BDC) (BDC = terephthalic) is infiltrated with DABCO (1,4-diazabicyclo[2,2,2]octane), the electrical conductivity of Ni(BDC) demonstrates a significant increase, and the power factor finally reaches 1.5 x 10(-3) W m(-1) K-2 at 300 K. The high electrical conductivity arises from the interaction between 3d(z2) orbital of Ni and the 2p(z). orbital of N in DABCO. The p-d orbital coupling leads to the electron delocalization on HOMO and also the decrease in carriers effective mass. Our results provide a useful strategy for increasing the conductivity of MOFs and suggest that MOFs can be a promising class of thermoelectric materials.