Compositionally Designed 2D Ruddlesden–Popper Perovskites for Efficient and Stable Solar Cells

Perovskite solar cells have emerged as one of the most promising candidates for next-generation solar cells. However, their instability remains challenging for practical applications. Here, the authors aim to enhance the stability and efficiency simultaneously by tuning the organic components in 2D Ruddlesden−Popper perovskites (2D-RPPs). Four groups of 2D-RPPs are prepared and the influence of 4-fluorophenethylammonium (FPEA) and formamidinium (FA) cations on the film properties and device performance are investigated. The (FPEA) 2 (FA) 8 Pb 9 I 28 film is found to be exceptionally vertically orientated, showing enhanced charge transport and lower defect density. Its absorption edge substantially extends in the IR region, which greatly increases the photocurrent. A high efficiency of 16.15% along with a V oc of 1.07 V and a J sc of 20.88 mA cm −2 is achieved for the (FPEA) 2 (FA) 8 Pb 9 I 28 solar cell. Notably, the (FPEA) 2 (FA) 8 Pb 9 I 28 film exhibits good humidity stability and remarkably enhanced thermal stability. Its unencapsulated device maintains 95% of its starting efficiency after 2112 h when exposed to ambient air with 30–70% relative humidity, which is superior than those of the reported (PEA) 2 (MA) 8 Pb 9 I 28 and (FPEA) 2 (MA) 8 Pb 9 I 28 solar cells. The study demonstrates that enhanced performance of 2D-RPPs can be obtained by strategically designing organic compositions, which paves an avenue toward the commercialization of 2D-RPP devices.