Protic Solvent-Assisted Ligand Regulation for Stable Inverted Perovskite Quantum Dot Solar Cells

Organic–inorganic hybrid FAPbI 3 perovskite quantum dots (PQDs) exhibit immense potential for next-generation solar cells (SCs) due to their exceptional optoelectronic properties. However, inefficient charge transport caused by insulating ligands and surface defects resulting from incomplete ligand exchange collectively limit the enhancement of their photovoltaic performance. This work reports a synergistic strategy combining solvent-mediated ligand exchange with an inverted p-i-n device architecture. The protic solvent isopropanol (IPA), with its high dielectric constant, effectively strips the insulating oleylamine (OAm) ligands from the PQD surface, thereby enhancing electronic coupling between the quantum dots. Concurrently, the eco-friendly ligand 2-pyridine methylammonium hydroiodate (2-PyAI) passivates surface defects, significantly suppressing nonradiative recombination. Notably, the resulting PQD film exhibits excellent energy-level alignment with the charge transport layers, minimizing interfacial losses. Inverted PQDSCs fabricated using this strategy achieved a champion power conversion efficiency (PCE) of 12.09%. Benefiting from effective surface passivation and the dopant-free nature of the charge transport layers in the p-i-n structure, the unencapsulated devices demonstrate outstanding ambient stability, retaining over 86% of their initial PCE after 3200 h of storage in ambient conditions. This study provides a feasible solution for addressing charge transport and stability challenges in PQDSCs by integrating ligand engineering with device architecture optimization.