Improved performance in inverted organic solar cell using two p-doped layers to modify the interface between anode and photoactive layer

Abstract

Inverted organic solar cells (OSCs) have been fabricated using MoO3 doped N,N'-bis-(1-naphthyl)-diphenyl-1,1′-biphenyl-4,4′-diamine (NPB:MoO3), MoO3 doped 4,4′-N,N'-dicarbazole-biphenyl (CBP:MoO3), and combined CBP:MoO3/NPB:MoO3 as anode modifying layers (AMLs), respectively. The CBP:MoO3/NPB:MoO3/anode increases fill factor of device than the NPB:MoO3/anode and CBP:MoO3/anode, mostly because the former enhances hole injection into photoactive layer than the latter two. The CBP:MoO3/NPB:MoO3/anode and CBP:MoO3/anode increase open-circuit voltage of device than the NPB:MoO3/anode, due to the larger work function of CBP:MoO3 than that of NPB:MoO3. It is also found that combined CBP:MoO3/NPB:MoO3 enhances short-circuit current density of device than single NPB:MoO3 and CBP:MoO3, mainly ascribed to the fact that the former improves absorptance of device than the latter two. As a result, the CBP:MoO3/NPB:MoO3/anode improves power conversion efficiency of device than the NPB:MoO3/anode and CBP:MoO3/anode. We present a useful concept to develop high-performance AMLs for inverted OSCs.