Layered two-dimensional (2D) perovskites are emerging photovoltaic materials due to their good environmental and structural stability thanks to the bulky organic spacers incorporated in the crystal lattice. Formamidine (FA) is an indispensable organic cation in high-performance 3D perovskite materials, whereas FA derivative-based spacers have remained largely unexplored in 2D perovskite. Here, we demonstrated a class of aromatic formamidinium (ArFA) spacers, namely, benzamidine (PhFA) and para-fluorobenzamidine (p-FPhFA), for efficient 2D Ruddlesden–Popper (RP) perovskite solar cells. It is found that the 2D perovskite with the fluorinated spacer p-FPhFA shows significantly improved charge carrier lifetime, enhanced mobility, and reduced trap density in comparison with an unfluorinated PhFA spacer. As a result, the p-FPhFA-based 2D perovskite (n = 5) device yields a champion efficiency of 17.37%, which is much higher than that of the PhFA-Pb device (12.92%), representing a record value for 2D PSCs with FA-based spacers. These results highlight the great potential of ArFA spacers, especially the fluorinated ArFA spacer, for high-performance 2D perovskite solar cells.

Two-dimensional Dion–Jacobson (DJ) perovskites have shown improved structure stability in comparison with Ruddlesden–Popper (RP) perovskites. However, the mechanism behind the improved stability is still largely unexplored. Here a multifluorinated aromatic spacer, namely, 4F-PhDMA, has been successfully developed for 2D DJ perovskites. It is found that the 2D DJ perovskite with a 4F-PhDMA spacer exhibits a high dissociation energy due to the multiple noncovalent interactions. The optimized 2D DJ device based on the 4F-PhDMA spacer (n = 4) exhibits a champion efficiency of 16.62% with much improved light and thermal stability. This efficiency is much higher than that of the control device using an unfluorinated spacer (n = 4, PCE = 10.11%) and is among the highest efficiencies in aromatic-spacer-based 2D DJ perovskite solar cells (PSCs). Our work highlights the importance of incorporating multiple noncovalent interactions in the 2D DJ perovskite by employing a multifluorinated aromatic spacer to achieve DJ PSCs with both high efficiency and high stability.

2D Dion–Jacobson (DJ) perovskites have become emerging photovoltaic materials owing to their intrinsic structure stability. However, as insulating aliphatic cations are widely used as spacers, the interactions between the spacers and inorganic layers in DJ perovskites have rarely been studied. Here, an organic semiconductor spacer with two covalently connected thiophene rings, namely bithiophene dimethylammonium (BThDMA), is successfully developed for 2D DJ perovskite solar cells (PSCs). An important finding is that there are strong orbital interactions between the conjugated organic spacer and adjacent inorganic layers, whereas no such interactions exist in DJ perovskite using an aliphatic octane‐1,8‐diaminium (ODA) spacer with similar length. The BThDMA spacer with multiple conjugated aromatic rings can also induce crystal growth with large grain size and preferred vertical orientation, resulting in reduced trap density and improved charge‐carrier mobility. As a result, the optimized device based on (BThDMA)MAn−1PbnI3n+1 (nominal n = 5) shows an excellent PCE of 18.1% with negligible hysteresis, which is a record efficiency for 2D DJ PSCs using a spacer with two or more covalently linked aromatic rings. These findings provide a novel and important insight on achieving efficient and stable 2D DJ perovskite solar cells by developing organic semiconductor spacers.

2D Ruddlesden–Popper (RP) perovskites have become emerging photovoltaic materials due to their outstanding optoelectronic properties and intrinsic structure stability. Here, two structurally similar organic spacers with conjugated and unconjugated unites, namely FuMA and THFMA, were developed to study their effects on the photophysical properties of 2D RP perovskites. A very important finding is that the 2D perovskite film (n = 4) based on FuMA with a conjugated furan unit exhibits an ultralong average carrier lifetime of 18.03 μs, which could be attributed to the enlarged dielectric constant, reduced exciton binding energy, and decreased electron–phonon coupling coefficients of the FuMA-based 2D RP perovskites. The optimized device based on the FuMA spacer achieves a high PCE of 18.00% with negligible hysteresis, much higher than that of the THFMA-based device (PCE = 13.79%). This work opens a new avenue for developing 2D RP perovskite films with ultralong carrier lifetimes for photovoltaic and other optoelectronic applications.

Integrated perovskite/organic solar cells (IPOSCs) have shown great potential in broadening the light absorption range and improving the photovoltaic performance. However, the severe interface charge recombination and unmatched energy levels between perovskite and organic photoactive layers hinder their performance improvement. Here, an efficient interface passivation strategy for IPOSCs based on a layered Ruddlesden-Popper (RP) perovskite and high photovoltaic performance is successfully demonstrated. It is found that an ultrathin conjugated polymer (PM6) layer could passivate the surface defects of perovskite film, tuning the energy level and suppress the nonradiative recombination loss, leading to efficient interface contact between RP perovskite and organic photoactive layers, boosting the open-circuit voltage from 1.06 to 1.12 V and the efficiency from 17.23% to 19.15%. Importantly, the optimized device shows extended photocurrent response to 930 nm with a peak intensity close to 50% from 800 to 931 nm. The results indicate that interface passivation using a functionalized polymer could be an efficient strategy to improve the photovoltaic performance of integrated devices.

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Because of their low cost, safety, and green nature, aqueous zinc-ion batteries (AZIBs) have become attractive energy storage devices. However, problems such as zinc dendrites have been hindering the development of AZIBs. Here, two materials polyacrylamide (PAM) and polypropylene (PAN) are used to modify the surface of zinc. The experimental results show that the coating of the two organic membranes can effectively improve the electrochemical performance of the AZIBs. Symmetric Zn/PAM||Zn/AM and Zn/PAN||Zn/PAN can steadily work over 12000 min at 0.5 mA cm−2, which is greater than that of bare Zn||Zn. At 0.2 C multiplicity, the full cell with the zinc negative electrode modified by both materials exhibited a stable cycle retention rate close to 40% of the initial value after 100 cycles.