Highly efficient organic tandem solar cell with a SubPc interlayer based on TAPC:C(70) bulk heterojunction

We report a small molecule tandem organic photovoltaic (OPV) cell with a high power conversion efficiency (PCE) of 7.27%. This cell contains two subcells with an identical mixed active layer of C(70):5 wt%TAPC (1,1-bis-(4-bis(4-methyl-phenyl)-amino-phenyl)-cyclohexane). The performance was dramatically improved by simply inserting a thin boron subphthalocyanine chloride (SubPc) interlayer, which results in an increase of the short-circuit current and open-circuit voltage as well as a decrease of the series resistance of the tandem cell. The response of the cell only contributed from the absorption of C(70). The high PCE was attributed to the high absorption efficiency of C(70) and improved holes extraction efficiency at the anode due to the band bending occurs at both MoO(3)/SubPc and SubPc/C(70):5 wt%TAPC interfaces.