Hole-transport materials (HTMs) play a crucial role in determining the photovoltaic performance and long-term stability of perovskite solar cells (PSCs), because they not only efficiently facilitate hole-extraction and transfer, but also act as a barrier to protect the perovskite from moisture and oxygen. So far, the power conversion efficiencies (PCEs) over 20% in PSCs have been mostly achieved by employing a Spiro-OMeTAD-based HTM. However, it suffers from some drawbacks such as relatively low hole-mobility, complicated synthesis and difficult purification, which hamper its potential commercial applications. Here, for the first time, two new easily accessible 9,9-bis(4-methoxyphenyl)-substituted fluorene-based HTMs comprising H (YT1) and methoxyphenyl-fluorene (YT3) as the terminated groups have been synthesized for use in organic–inorganic hybrid and all-inorganic PSCs. The (FAPbI₃)_0.85(MAPbBr₃)_0.15 and CsPbI₂Br PSCs based on YT3 yield very impressive PCEs of 20.23% and 13.36%, respectively, both of which are higher than that of Spiro-OMeTAD (19.18% and 12.30%). More encouragingly, the YT3-based PSC displays good long-term stability for 600 hours. These results confirm that different terminated groups in HTMs show a significant effect on the energy levels, hole extraction and transfer, thin-film surface morphology and photovoltaic performance. Our findings could provide a useful insight for future rational design of HTMs for highly efficient and stable PSCs.

中文翻译：

---

9,9-双（4-甲氧基苯基）取代的芴基空穴传输材料中的端基对高效有机-无机杂化和全无机钙钛矿太阳能电池的重要性†

空穴传输材料（HTM）在确定钙钛矿太阳能电池（PSC）的光伏性能和长期稳定性方面起着至关重要的作用，因为它们不仅有效地促进了空穴的提取和转移，而且还充当了保护钙钛矿太阳能电池的障碍。水分和氧气产生的钙钛矿。到目前为止，通过采用基于Spiro-OMeTAD的HTM，大部分已经实现了PSC中20％以上的功率转换效率（PCE）。然而，它具有一些缺点，例如相对较低的空穴迁移率，复杂的合成和难以纯化，这阻碍了其潜在的商业应用。在这里，首次有两个新的易于访问的9,9-双（4-甲氧基苯基）取代的芴基HTM，包括H（YT1）和甲氧基苯基芴（YT3），因为已合成了用于有机-无机杂化和全无机PSC的封端基团。基于YT3的（FAPbI ₃）_0.85（MAPbBr ₃）_0.15和CsPbI ₂ Br PSC分别产生非常令人印象深刻的PCE，分别为20.23％和13.36％，均高于Spiro-OMeTAD（分别为19.18％和12.30％）。 。更令人鼓舞的是，YT3的PSC在600小时内显示出良好的长期稳定性。这些结果证实，HTM中不同的封端基团对能级，空穴提取和转移，薄膜表面形态和光伏性能均具有显着影响。我们的发现可以为将来高效，稳定的PSC合理设计HTM提供有用的见解。