Computational design and selection of optimal building blocks and linking topologies for construction of high-performance host materials

Two typical hole transport groups, carbazole and diphenylamine, and two typical electron transport groups, diphenylphosphine oxide and triphenylsilane, were linked to biphenyl at its ortho/meta/para-positions to investigate the effects of building blocks and linking topologies on the structural and electronic properties of such constructed host materials via density function theory calculation. It is found that the frontier orbital levels, energy band gap, and triplet energy of host molecules can be effectively tuned by different building blocks and linking topologies. The electron-transporting nature of π-conjugated molecules can be enhanced by connecting electron-withdrawing building blocks at the ortho or meta position, but not at the para-position. Employing asymmetric building blocks with meta-type topology would be an effective strategy for the design of high-performance bipolar host materials.