LAUSR

Abstract Plane wave periodic Density Functional Theory (DFT) calculations were performed to investigate MoO 3 surfaces and MoO 3 /ZnO interfaces to understand the effect of transition metal oxide overlayers on the workfunction of ZnO surfaces. To construct computationally feasible interfaces with small lattice mismatches, a set of strain variables was introduced to measure the lattice mismatch of interface models. Based on this, the MoO 3 (0 1 0)/ZnO (0 0 0 1) interface was constructed and fully relaxed within DFT. In order to accurately predict the workfunction of the interface, pseudo-hydrogen atoms were introduced to compensate the net dipole moment of the ZnO slab with ( 0 0 0 1 ) / ( 0 0 0 1 ¯ ) terminations. The results show that the workfunction of ZnO ( 0 0 0 1 ) surface increased from 6.9 eV to 7.4 eV when it has one layer of MoO 3 (0 1 0) overlayer. However, with further increases of the MoO 3 slab thickness, no appreciable increase of workfunction was observed suggesting full coverage of a thin layer of transition metal oxide can be an effective way of increasing the workfunction of ZnO for display and flexible OLED applications.