1+1 > 2: Dual strategies of quinolinic acid passivation and DMF solvent annealing for high-performance inverted perovskite solar cell

We developed a new combined method in which quinolinic acid (QA) passivation and DMF solvent annealing are carried out sequentially to enhance the performance of inverted perovskite solar cells. Upon systematic inves-tigation, we found that: 1). One QA molecule not only passivates more than one defects within lattice or neighboring lattices, creating a multi-passivation effect, but also enhances the interactions between lattices, due to pyridine ring and dicarboxylic acid functional groups in the molecule; 2). By combining with DMF solvent annealing post-treatment sequentially, high quality perovskite films with very large grain size over 1 mu m are obtained on the substrate of PEDOT: PSS. As a result, the PSC fabricated with the combined method demonstrates an excellent humidity stability and yields a PCE of 18.56% with 20% and 11.6% increment of V-oc and J(sc), respectively. To the best of our knowledge, it is the highest reported PCE for inverted PSCs with undoped PEDOT: PSS as hole transporting layer. Therefore, our work indicates that the combined strategy of multi-passivation with QA and solvent annealing with DMF sequentially has a significant potential for highly-efficient and sta-ble inverted planar PSCs.