Recycled Upgrading Hole Transport Material Advances Closed-Loop Sustainable Perovskite Solar Cells

Developing a thoroughgoing recovery technology that allows simultaneously separating and recovering all functional layers of the end-of-life perovskite solar cells (PSCs), in keeping with maintaining potent device efficiency and eco-environment friendliness, is crucial toward the sustainability of PSCs. Herein, we propose a facile closed-loop recycling strategy to realize the acquisition and reutilization of hole transport material and other retrievable components from obsolete PSCs, employing chlorobenzene and dimethylformamide to sequentially dissolve the spiro-OMeTAD and perovskite layers. Surprisingly, the recycled spiro-OMeTAD, i.e., oxidized spiro-OMeTAD (spiro-OMeTAD^•+) endows reinforced conductivity and hole mobility, favorable energy band alignment, and mitigated perovskite defects, thus resulting in expedited hole extraction and lessened nonradiative recombination loss. Along with the dissolution of the spiro-OMeTAD and perovskite layers, other functional materials involving Ag, PbI₂, and ITO/SnO₂ are concurrently recovered. Note that the solubilizers are also recycled to eliminate the alien reagents to environmental hazards. The refabricated PSC based on the recovered materials delivers an upgrading power conversion efficiency of up to 23.41% together with an open circuit voltage of 1.17 V, outperforming the control device based on fresh materials (20.77%, 1.11 V). Overall, this strategy holds promise for realizing closed-loop recycling of end-of-life PSCs, and thus pushes future PSCs sustainability.