All‐Oxide MoO<i>_x</i>/SnO<i>_x</i> Charge Recombination Interconnects for Inverted Organic Tandem Solar Cells

Abstract

Abstract Multijunction solar cells are designed to improve the overlap with the solar spectrum and to minimize losses due to thermalization. Aside from the optimum choice of photoactive materials for the respective sub‐cells, a proper interconnect is essential. This study demonstrates a novel all‐oxide interconnect based on the interface of the high‐work‐function (WF) metal oxide MoO x and low‐WF tin oxide (SnO x ). In contrast to typical p‐/n‐type tunnel junctions, both the oxides are n‐type semiconductors with a WF of 5.2 and 4.2 eV, respectively. It is demonstrated that the electronic line‐up at the interface of MoO x and SnO x comprises a large intrinsic interface dipole (≈0.8 eV), which is key to afford ideal alignment of the conduction band of MoO x and SnO x , without the requirement of an additional metal or organic dipole layer. The presented MoO x /SnO x interconnect allows for the ideal (loss‐free) addition of the open circuit voltages of the two sub‐cells.