Efficient and stable perovskite solar cells based on a quasi-point-contact and rear-reflection structure with 22.5% efficiency

Abstract

In perovskite solar cells (PSCs), structure evolution that can retard the interfacial charge recombination or minimize the optical loss is of crucial importance for further efficiency development but still poses substantial challenges. Here, a novel quasi-point-contact and rear-reflection (PCRR) structure is developed for efficient PSCs by inserting a discontinuous dielectric interlayer between the perovskite film and hole transport layer (HTL). In this architecture, a large portion of perovskite/HTL contact areas, particularly the defect enriched grain boundaries, are separated by the insulating interlayer while some discrete point-contacts are reserved at the convex of some perovskite grains for hole transport. The point contact leads to significantly reduced perovskite/HTL contact areas and thus remarkably restrained interfacial charge recombination. Moreover, the polysilane with a smaller refractive index coated on the perovskite layer leads to a significant internal light reflection at the polysilane/perovskite interface. Due to the simultaneously reduced charge recombination loss and enhanced light-harvesting, the resulting PSC yields a remarkable efficiency increment from 20.96% to 22.49%. In addition, the humidity stability of the device is also remarkably improved due to the in situ encapsulation of the perovskite film by the cross-linked polysilane layer. This study paves a brand new way of interface engineering for efficient PSCs.