Ionic Liquid Stabilized Perovskite Solar Modules with Power Conversion Efficiency Exceeding 20%

Metal-halide perovskite solar cells (PSCs) exhibit outstanding power conversion efficiencies (PCEs) when fabricated as mm-sized devices, but creation of high-performing large-area modules that are stable on a sufficiently long timescale still presents a significant challenge. Herein, the quality of large-area perovskite film is improved by using ionic liquid additives via forming a new Pb-N bonding between the ionic liquid and Pb2+. This new bond can be modulated by a critical screening of the anion structure of the ionic liquid. The selected ionic liquid effectively reduces the defects of the perovskite films and markedly elongate their carrier lifetimes. As a result, a champion PCE of 24.4% for small-area (0.148 cm(2)) devices and 20.4% for larger-area (10.0 cm(2)) modules under AM 1.5G irradiation is achieved. More importantly, the modified devices retain 90% of their peak PCE after aging for 1900 h at 65 +/- 5 degrees C (ISOS-T-1) and 80% after continuous light soaking for 750 h. The non-encapsulated modules maintained 80% of their peak PCE after 1100 h of aging in the air with a relative humidity of 35 +/- 5% and temperature of 25 +/- 5 degrees C under dark (ISOS-D-1), showing great potential for future commercialization.

Automated summary

Improving the quality of large-area perovskite film using ionic liquid additives and a new bond formation has shown significant improvements in the power conversion efficiency of the devices, making them more stable for extended periods of time.