上海科技大学知识管理系统

["Power conversion efficiencies (PCEs) of the methylammonium-free (MA-free) perovskite solar cells (PSCs) are constantly lagging behind those of the most extensively researched triple cation mixed PSCs due to their subpar perovskite films. Here, two guanidine-based passivation agents are proposed, that are, sulfaguanidine (S-Gua) and 1-acetylguanidine (A-Gua) that can be applied to optimize the film quality of MA-free perovskite for minimizing the efficiency discrepancy between the two types of PSCs. Through strong coordination with Pb2+ and hydrogen bonding with formamidinium (FA+), the two passivation additives can reduce bulk defects and suppress non-radiative recombination, which in turn enhance the charge extraction and transfer efficiency. Consequently, the S-Gua- and A-Gua-treated devices achieve PCEs of 24.34% and 23.77%, respectively. Both PCEs are greater than that of the control device (23.03%), and the 24.34% PCE is comparable with that of the best MA-free inverted PSCs with narrower bandgaps. Moreover, the S-Gua-treated devices maintain 89.3% and 82.0% of their initial PCEs after aging for 800 h and heating (85 degrees C) for 340 h in ambient air without any encapsulation, respectively. This work offers comprehensive insights into the use of guanidine-based additives to achieve high-quality perovskite films and subsequently state-of-the-art MA-free PSCs.","S-Gua and A-Gua are used as passivation agents to enlarge the grain sizes and to reduce the defects of MA-free perovskite films by which high-efficiency and stable inverted perovskite solar cells are achieved. image"]