Enhanced Organic Solar Cell Stability through the Effective Blocking of Oxygen Diffusion using a Self-Passivating Metal Electrode

A new and simple strategy for enhancing the stability of organic solar cells (OSCs) was developed by using self-passivating metal top electrodes. Systematic investigations on O₂ permeability of Al top electrodes revealed that the main pathways for oxidation-induced degradation could be greatly suppressed by simply controlling the nanoscale morphology of the Al electrode. The population of nanoscale pinholes among Al grains, which critically decided the diffusion of O₂ molecules toward the Al-organic interfaces that are vulnerable to oxidation, was successfully regulated by rapidly depositing Al or promoting lateral growth among the Al grains, accompanied by increasing the deposition thickness. Our observations suggested that the stability of OSCs with conventional architectures might be greatly enhanced simply by controlling the fabrication conditions of the Al top electrode, without the aid of additional secondary treatments.