Spiro‐OMeTAD is one of the most used hole transport layers (HTLs) in high efficiency n‐i‐p perovskite solar cells (PSCs). However, due to the unsatisfactory conductivity of pristine Spiro‐OMeTAD, additives such as tert‐butylpyridine (tBP) and lithium bis (trifluoromethylsulfonyl)‐imide (LiTFSI) are required to improve its hole transportation. The hygroscopic nature of these additives inevitably deteriorates the device's stability. Here, it is shown that by adding fluorinated graphene (FG) into the Li‐TFSI and tBP doped Spiro‐OMeTAD, both efficiency and stability of the PSCs are significantly enhanced. Using the FG incorporated Spiro‐OMeTAD HTL, the power conversion efficiency (PCE) of the PSC reaches 21.92%, which is 11.8% higher than the original device. The FG not only improves the hole mobility of Spiro‐OMeTAD but also effectively reduces the amount of lithium ions in the perovskite layer and improves the hydrophobicity of the HTL. The FG incorporating cell shows better stability, maintaining 90% of initial efficiency over a 2400 h test in ambient conditions with 25% humidity. Finally, it is further demonstrated that the valence band of FG incorporated Spiro‐OMeTAD HTL has a positive effect on PSCs with a 2D interfacial layer, achieving an impressive PCE of 23.14% and a Voc of 1.226 V.
Rechargeable aqueous zinc-ion batteries (ZIBs) have been considered as a promising candidate for the large-scale energy storage device owing to their low cost and high safety. However, the practical application of aqueous ZIBs at low temperature environment is hindered by the freezing aqueous electrolytes, which leads to a sharp drop in ionic conductivity, and thereby a rapid deterioration of battery performance. Herein, a chaotropic salt electrolyte based on low concentration aqueous Zn(ClO 4 ) 2 with superior ionic conductivity under low temperature (4.23 mS/cm at À50 C) is reported. The anti-freezing methodology introduced here is completely different from conventional freezeresistant design of using "water-in-salt" electrolyte, cosolvents, or anti-freezing agent additives strategy. Experimental analysis and molecular dynamics simulations reveal that the as-prepared Zn(ClO 4 ) 2 electrolyte possesses faster ionic migration compared with other commonly used Zn-based salts (i.e., Zn (CF 3 SO 3 ) 2 and ZnSO 4 ) electrolyte. It is found that Zn(ClO 4 ) 2 electrolyte can suppress the ice crystal construction by forming more hydrogen bonds between solute ClO 4 À and solvent H 2 O molecules, thus leading to a superior anti-freezing property. The fabricated ZIBs using this aqueous electrolyte exhibits a dramatically enhanced specific capacity, remarkable rate capability, and great cycling stability over a wide temperature range, from À50 to 25 C. The aqueous ZIBs also exhibit an outstanding energy density of Guoshen Yang, Jialei Huang, and Xuhao Wan contributed equally to this work.
Locust bean gum was utilized to prepare a free-standing quasi-solid-state ZnSO4/MnSO4 electrolyte. Zinc-ion batteries with locust bean gum electrolyte achieved high energy density and superior lifetime.
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