Synergetic Passivation of Metal-Halide Perovskite with Fluorinated Phenmethylammonium toward Efficient Solar Cells and Modules

Surface passivation with organic halide salts is a powerful strategy to enhance the performance of perovskite solar cells. However, the inevitable formed in-plane favored two-dimensional perovskite layers with low carrier mobility and high binding energy inhibit the interfacial charge transfer within the device. Herein, a bulky fluorinated phenmethylammonium salt is designed and synthesized to passivate the perovskite film without forming 2D perovskites. A strong interaction which is induced by an electron donation from passivation agent to perovskite not only reduces the defects at the top surface of the perovskite, but also suppresses the recombination reaction at the buried surface due to a permeation of the organic halide salt. Moreover, the results of time resolved photoluminescence and confocal microscopy images suggest that the interfacial charge transfer speed and uniformity are enhanced. As a result, the efficiency of a small-area device increases from 20.7 +/- 0.9% to 22.8 +/- 0.4% (aperture: 0.16 cm(2)). Moreover, a stabilized efficiency of 18.0% (aperture: 10.0 cm(2)) is achieved for larger-area modules with 6-series connected sub-cells. Equally important, the non-encapsulated modules show significantly improved stability at ambient conditions (ISOS-D-1). These significant improvements provided by a simple and reproducible procedure can be readily adopted in other types of devices.

Automated summary

Surface passivation with a bulky fluorinated phenmethylammonium salt is found to enhance the performance of perovskite solar cells by reducing defects, suppressing recombination, and improving interfacial charge transfer. The efficiency of small-area devices increased from 20.7 +/- 0.9% to 22.8 +/- 0.4%, and a stabilized efficiency of 18.0% was achieved for larger-area modules. Additionally, non-encapsulated modules showed improved stability at ambient conditions.