The current work has investigated computationally the phenyl substituent and nitrogen doping effects on the electronic properties and charge transport parameters for tetrabenzoheptacene(TTBH)by means of density functional theory(DFT)calculations at the B3LYP/6-31G(d,p)level.Results show the nitrogen doping remarkably lowers the HOMO and LUMO levels,and favors the electron injection,while the phenyl substitution increases HOMO and LUMO.In addtion,calculated results also reveal that the nitrogen doping can largely decrease the hole reorganization energy,while the phenyl substitution tends to increasing it.Compared with obtained electronic couplings,it is found that due to the steric effect of phenyl substitution,the largest Ve and Vh values are remarkable small in Ph-TTBH crystal,3.76 and 5.06 meV.Based on predicted μ values,TTH is found to prefer transporting holes(2.67cm2 V-1s-1),while TTBH favors electron transport(2.11cm2 V-1s-1).