A multifunctional piperidine-based modulator for printable mesoscopic perovskite solar cells

Printable mesoscopic perovskite solar cells (PSCs) have received extensive attention due to their convenient large-area fabrication and good stability. The further improvement of the power conversion efficiency (PCE) of such simplified PSC configuration is limited by the low open circuit voltage (VOC). The high density of defects at grain boundaries of perovskites inside the mesoporous scaffold can cause severe nonradiative recombination, which have negative effects on VOC. Additive engineering has demonstrated advantages in improving the perovskite crystallization inside the pores, passivating the defects of perovskite and enhancing the performance of printable mesoscopic PSCs. Herein, we introduce a multifunctional modulator 1-(2-Chloroethyl) piperidine hydrochloride (ClEP) as an additive into the perovskite precursor solution. Benefiting from the strong interaction between ClEP and perovskite, it can interact with non-coordinating ions and defect states to achieve multi-defect passivation. As a result, the VOC of the printable mesoscopic PSC increases from 895.25 mV to 982.24 mV and the ClEP-treated printable mesoscopic PSC reaches a champion PCE of 17.08%. This work provides a new approach for developing efficient printable mesoscopic PSCs.