Rejuvenating Aged Perovskite Quantum Dots for Efficient Solar Cells

Perovskite quantum dots (PQDs) have emerged as one of the most promising candidates for next-generation solar cells owing to its remarkable optoelectronic properties and solution processability. However, the optoelectronic properties of PQDs suffer from severe degradation in storage due to the dynamically binding ligands, predominantly affecting photovoltaic applications. Herein, an in situ defect healing treatment (DHT) is reported to effectively rejuvenate aged PQDs. Systematically, experimental studies and theoretical calculations are performed to fundamentally understand the causes leading to the recovered optoelectronic properties of aged PQDs. The results reveal that the I₃⁻ anions produced from tetra-n-octylammonium iodide and iodine could strongly anchor on the surface matrix defects of aged PQDs, substantially diminishing the nonradiative recombination of photogenerated charge carriers. Meanwhile, an DHT could also renovate the morphology of aged PQDs and thus improve the stacking orientation of PQD solids, substantially ameliorating charge carrier transport within PQD solids. Consequently, by using a DHT, the PQD solar cell (PQDSC) yields a high efficiency of up to 15.88%, which is comparable with the PQDSCs fabricated using fresh PQDs. Meanwhile, the stability of PQDSCs fabricated using the rejuvenated PQDs is also largely improved.