Over-18%-Efficiency Quasi-2D Ruddlesden–Popper Pb–Sn Mixed Perovskite Solar Cells by Compositional Engineering

Abstract

Quasi-two-dimensional (2D) Pb–Sn mixed perovskites show great potential in applications of single and tandem photovoltaic devices, but they suffer from low efficiencies due to the existence of horizontal 2D phases. Here, we obtain a record high efficiency of 18.06% based on 2D ⟨n⟩ = 5 Pb–Sn mixed perovskites (iso-BA2MA4(Pb x Sn1–x )5I16, x = 0.7), by optimizing the crystal orientation through a regulation of the Pb/Sn ratio. We find that Sn-rich precursors give rise to a mixture of horizontal and vertical 2D phases. Interestingly, increasing the Pb content can not only entirely suppress the unwanted horizontal 2D phase in the film but also enhance the growth of vertical 2D phases, thus significantly improving the device performance and stability. It is suggested that an increase of the Pb content in the Pb–Sn mixed systems facilitates the incorporation of iso-butylammonium (iso-BA+) ligands in vertically oriented perovskites because of the reduced lattice strain and increased interaction between the organic ligands and inorganic framework. Our work sheds light on the optimal conditions for fabricating stable and efficient 2D Pb–Sn mixed perovskite solar cells.

Imidazole Derivative Assisted Crystallization for High‐Efficiency Mixed Sn–Pb Perovskite Solar Cells

“…[6,7] DOI: 10.1002/adfm.202310828 However, the rapid crystallization of tincontaining perovskite leads to the easy formation of defect in the bulk or at the interfaces of perovskite films. [8] Meantime, Sn 2+ is easily oxidized to Sn 4+ , resulting in serious p-type doping. [9,10] Different strategies have been adopted to address these issues.…”

Narrow Bandgap Metal Halide Perovskites for All-Perovskite Tandem Photovoltaics

“…Several attempts have been made using accustomed processing techniques, such as vacuum-assisted growth, gas-quenching, or two-step processing, to manipulate the crystallization kinetics. Other, more established protocols propose the use of 2D materials for controlling the growth and orientation of the grains, − with close reliance on the perovskite compositions in some cases, and the addition of SnF 2 to deliver more homogeneous nucleation of neat Sn-based perovskite films through the action of the F − anion . In this aspect, reports on the use of chloride-containing additives suggest that this halide would have a similar role to the F − anion .…”

Annual research review of perovskite solar cells in 2023

“…To further enhance the performance of 2D Pb-Sn PSCs, Qin et al explored the preferred crystal orientation by tuning the Pb/Sn ratio. A superior PCE of 18.06% was achieved based on 2D RP Pb-Sn PVKs (iso-BA 2 MA 4 (Pb x Sn 1-x ) 5 I 16 ) (n = 5 and x = 0.7) [169]. Introducing a multifunctional 2D PVK layer with an antioxidation capability is ideal for enhancing the performance of Pb-Sn PSCs by relying on the dopamine cation (DAH + ) organic spacer with reductive capability.…”