Interfacial defect passivation and stress release by multifunctional KPF6 modification for planar perovskite solar cells with enhanced efficiency and stability

Abstract

• The multifunctional KPF 6 is developed to modify SnO 2 /perovskite interface. • PF 6 − is revealed to be able to chemically link SnO 2 layer and perovskite layer. • KPF 6 modification leads to interfacial defect passivation and stress release. • The moisture, thermal and light stability are increased after KPF 6 modification. Interfacial defect and residual stress hinder the further enhancement of power conversion efficiency (PCE) and stability of perovskite solar cells (PSCs). Here, we report a multifunctional interface modification strategy where KPF 6 molecule is employed to modify SnO 2 /perovskite interface. It is revealed that PF 6 − is still located at interface whereas most of K + ions diffuse into perovskite layer. PF 6 − can chemically link SnO 2 layer and perovskite layer via the hydrogen bond with perovskites and coordination bond with SnO 2 , resulting in improved interfacial contact. KPF 6 interface modification leads to improved perovskite film quality, interfacial defect passivation, and interfacial stress release. As a result, the KPF 6 -modified device achieves an efficiency enhancement from 19.66% to 21.39% as compared to the control device. Meanwhile, moisture, thermal and light stability are ameliorated after interface modification. The unencapsulated KPF 6 -modified device maintains 80.1% of its initial PCE after aging for 960 h at 60 °C and 57.2% after aging for 960 h under one sun illumination, respectively. This work provides an idea for developing multifunctional interface molecules toward simultaneously enhancing efficiency and stability of PSCs.