In the past decade, perovskite solar cells (PSCs) have experienced a rapid development with the goal of achieving both high efficiency and high stability. Avoiding the use of unstable methylammonium, formamidinium-based perovskites, with better thermal stability and lower band gap, have became promising candidate absorbers. However, the methylammonium-free PSCs usually show inferior PCEs, which is closely related to the crystalline quality of these perovskites. In this study, we propose a formamidine-assisted fast crystallization (FAAFC) method to regulate the nucleation and improve the crystallization by using an FA-containing chlorobenzene antisolvent. It was found that RbCsFAPbI₃ films prepared using the FAAFC method have a preferred orientation, larger crystal size and less grain boundary and traps. As a result, their inverted PSCs exhibit much better photovoltaic performance and stability compared to with the control method, achieving a PCE of 20.58% and <10% degradation after 500 h illumination.

中文翻译：

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甲am辅助快速结晶，以制备甲form基钙钛矿薄膜，用于高效稳定的太阳能电池

在过去的十年中，钙钛矿太阳能电池（PSC）经历了飞速发展，以实现高效率和高稳定性为目标。避免使用不稳定的甲基铵，具有更好的热稳定性和较低的带隙的基于甲ami的钙钛矿已成为很有前途的候选吸收剂。但是，不含甲基铵的PSC通常显示较差的PCE，这与这些钙钛矿的晶体质量密切相关。在这项研究中，我们提出了一种甲form辅助快速结晶（FAAFC）方法，以通过使用含FA的氯苯抗溶剂来调节成核并改善结晶。发现RbCsFAPbI ₃用FAAFC方法制备的薄膜具有较好的取向，较大的晶体尺寸和较少的晶界和陷阱。结果，与控制方法相比，其倒置的PSC表现出更好的光伏性能和稳定性，在500 h照射后PCE达到20.58％，降解<10％。