To explore the novel application of the hole-transporting material (HTM) as exciton blocking layer (EBL) in small molecule organic photovoltaic (OPV) cells, we introduce a recently reported HTM, 5,10,15-tribenzyl-5H-diindolo[3,2-a:3',2'-c]-carbazole (TBDI), and the other two traditional HTMs, N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB) and 1,1'-bis(di-4-tolylaminophenyl)cyclohexane (TAPC), to serve as EBLs in the tetraphenyldibenzoperiflanthene (DBP) based planar heterojunction cells. Due to the large band gap of these materials, the EBLs successfully block the misdirected electrons. The optimized devices including the EBLs of TBDI, NPB and TAPC achieve power conversion efficiency (eta(PCE)) of 1.70%, 1.33%, and 1.33%, respectively, whereas the control device without any EBL shows a eta(PCE) of only 1.25%. The optical simulation indicates that the maximum optical electric fields for the PHJs including 10-nm EBLs at the wavelength of 610 nm are significantly enhanced relative to that for the 20-nm DBP based control device. By impedance spectroscopy measurement, the device with TBDI EBL shows lower series resistance and total resistance than the device without TBDI, suggesting fast internal carrier mobility and smaller carrier recombination. The novel HTM TBDI better contributes to the device performance relative to the other two HTMs, stemming from its shallower lowest unoccupied molecule orbits (LUMO) level, stronger prevention of exciton quenching, and a smoother TBDI/DBP surface. These results suggest that TBDI is an excellent candidate as EBL for the DBP based OPVs. The overall eta(PCE) is further enhanced via optimizing the cathode buffer. (C) 2015 Elsevier B.V. All rights reserved.