Toward high efficiency for long-term stable Cesium doped hybrid perovskite solar cells via effective light management strategy

Power conversion efficiency (PCE) and device stability are the two most important concerns for next generation perovskite solar cells (PSCs). Herein, we report an investigation for long-term stable perovskite Cs0.05(FA0.85MA0.15)0.95Pb(I0.85Br0.15)3 solar cells toward high efficiency via the light management strategy. To that end, we first experimentally determine complex optical constants of this kind of perovskite thin film by using variable angle spectroscopic ellipsometry measurements. By constructing the proper model, the calculated photocurrent density (Jsc) of 23.2 mA/cm2 of the planar PSC model is only slightly higher than the measured 23.0 mA/cm2 of our champion planar cell with excellent consistency, where the PCE is up to 20.5% with active area of 0.16 cm2, demonstrating a long-term stability capable of retaining 91% of initial PEC for 40 days. It is further found that when the front texture of nanocone array design is applied to the planar cell as a surface antireflection, the Jsc value of 24.8 mA/cm2 with the resulting PCE of 22.1% is projected from the present real planar PSC device with active area of 0.16 cm2.