Organic molecular hole-transport materials (HTMs) are appealing for the scalable manufacture of perovskite solar cells (PSCs) because they are easier to reproducibly prepare in high purity than polymeric and inorganic HTMs. There is also a need to construct PSCs without dopants and additives to avoid formidable engineering and stability issues. We report here a power conversion efficiency (PCE) of 20.6% with a molecular HTM in an inverted (p–i–n) PSC without any dopants or interlayers. This new benchmark was made possible by the discovery that, upon annealing, a spiro-based dopant-free HTM (denoted DFH) containing redox-active triphenyl amine (TPA) units undergoes preferential molecular organization normal to the substrate. This structural order, governed by the strong intermolecular interactions of the DFH dioxane groups, affords high intrinsic hole mobility (1 × 10⁻³ cm² V⁻¹ s⁻¹). Annealing films of DFH also enables the growth of large perovskite grains (up to 2 μm) that minimize charge recombination in the PSC. DFH can also be isolated at a fraction of the cost of any other organic HTM.

中文翻译：

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在钙钛矿太阳能电池中介导20％功率转换效率的无掺杂分子空穴传输材料

有机分子空穴传输材料（HTM）吸引了钙钛矿太阳能电池（PSC）的可扩展生产，因为它们比聚合物和无机HTM更容易可重复生产高纯度。还需要构建不含掺杂剂和添加剂的PSC，以避免巨大的工程和稳定性问题。我们在这里报告在没有任何掺杂剂或中间层的情况下，在反向（p–i–n）PSC中使用分子HTM的功率转换效率（PCE）为20.6％。通过发现，退火后，含有氧化还原活性三苯胺（TPA）单元的无螺线型无掺杂HTM（表示为DFH）成为可能，这一新的基准成为可能，该分子具有垂直于底物的优先分子组织。这种结构顺序受分子之间强烈的分子间相互作用的支配。DFH二恶烷基团具有高的固有空穴迁移率（1×10 ^-3 cm ² V ^-1 s ^-1）。DFH退火膜还可以生长较大的钙钛矿晶粒（最大2μm），从而最大程度地减少PSC中的电荷重组。DFH也可以以任何其他有机HTM成本的一小部分进行隔离。