Chemically modifiable small-molecule hole transport materials (HTMs) hold promise for achieving efficient and scalable perovskite solar cells (PSCs). Compared to emerging self-assembled monolayers, small-molecule HTMs are more reliable in terms of large-area deposition and long-term operational stability. However, current small-molecule HTMs in inverted PSCs lack efficient molecular designs that balance both the charge transport capability and interface compatibility, resulting in a long-standing stagnation of power conversion efficiency (PCE) below 24.5%. Here, we report the comprehensive design of HTMs’ backbone and functional groups, which optimizes a simple planar linear molecular backbone with a high mobility exceeding 7.1 × 10^–4 cm² V^–1 S^–1 and enhances its interface anchoring capability. Owing to the improved surface properties and anchoring effects, the tailored HTMs enhance the interface contact at the HTM/perovskite heterojunction, minimizing nonradiative recombination and transport loss and leading to a high fill factor of 86.1%. Our work has overcome the persistent efficiency bottleneck for small-molecule HTMs, particularly for large-area devices. Consequently, the resultant PSCs exhibit PCEs of 26.1% (25.7% certified) for a 0.068 cm² device and 24.7% (24.4% certified) for a 1.008 cm² device, representing the highest PCE for small-molecule HTMs in inverted PSCs.

中文翻译：

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用于 >26% 高效倒置钙钛矿太阳能电池的小分子空穴传输材料


化学可改性的小分子空穴传输材料 （HTM） 有望实现高效和可扩展的钙钛矿太阳能电池 （PSC）。与新兴的自组装单层相比，小分子 HTM 在大面积沉积和长期操作稳定性方面更加可靠。然而，目前倒置 PSC 中的小分子 HTM 缺乏平衡电荷传输能力和界面兼容性的高效分子设计，导致功率转换效率 （PCE） 长期停滞在 24.5% 以下。在这里，我们报道了 HTMs 骨架和官能团的综合设计，它优化了一个简单的平面线性分子骨架，其高迁移率超过 7.1 × ^10-4 cm^{2 V-1 S-1}，并增强了其界面锚定能力。由于表面性能和锚定效应的改善，定制的 HTM 增强了 HTM/钙钛矿异质结处的界面接触，最大限度地减少了非辐射复合和传输损耗，并实现了 86.1% 的高填充因子。我们的工作克服了小分子 HTM 的持续效率瓶颈，特别是对于大面积器件。因此，所得 PSC 的 PCE 为 26.1%（25.7% 认证），0.068^{cm2 设备为} 24.7%（24.4% 认证），代表了倒置 PSC 中小分子 HTM 的最高 PCE。