Perovskite solar cells (PSCs) have drawn extensive attention as promising next-generation photovoltaics due to their exceptional power conversion efficiency (PCE) and low fabrication cost over the past 10 years. However, their poor stability remains the biggest barrier for commercialization. Among the many causes for device degradation, the inherent moisture instability of the perovskite structure is one of the main reasons for the poor stability of the PSCs. In addition, chemical dopants used to improve PCE further induce the moisture sensitivity of PSCs. Here, in this study, we report on the stability improvement of the PSCs by incorporating a hydrophobic element, fluorine, into the N,N,N′,N′-tetraphenylbenzidine structure as a dopant-free hole-transporting material (HTM). The optoelectronic, electrochemical, theoretical, and charge transport properties of the synthesized HTM were characterized by UV–vis absorption spectroscopy, cyclic voltammetry, density functional theory calculation, and space charge-limited current method. The hydrophobicity and surface roughness of the HTM film were investigated by the water contact angle analysis and atomic force microscopy, respectively. The PSCs were fabricated with the HTM, a nonfluorinated control molecule, and the commonly used spiro-OMeTAD in an ambient environment without encapsulation. Scanning electron microscopy was used to obtain topographic information of the perovskite layer and cross-sectional images of the devices. The devices with the fluorinated HTM exhibited the best PCE of 13.96%. The stability study under a controlled humid environment showed the improved moisture stability of the fluorinated devices compared to the control devices, indicating that the hydrophobic HTM successfully inhibits the moisture-induced damage to the perovskite structure.

中文翻译：

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氟化 N,N,N',N'-四苯基联苯胺衍生物作为耐湿钙钛矿太阳能电池的无掺杂空穴传输材料

在过去的 10 年中，钙钛矿太阳能电池 (PSC) 因其卓越的功率转换效率 (PCE) 和低制造成本而作为有前途的下一代光伏电池而受到广泛关注。然而，它们的稳定性差仍然是商业化的最大障碍。在器件退化的众多原因中，钙钛矿结构固有的水分不稳定性是导致 PSC 稳定性差的主要原因之一。此外，用于改善 PCE 的化学掺杂剂会进一步诱导 PSC 的湿度敏感性。在这里，在这项研究中，我们报告了通过将疏水元素氟引入N,N,N',N' 来提高 PSCs 的稳定性-四苯基联苯胺结构作为不含掺杂剂的空穴传输材料 (HTM)。通过紫外-可见吸收光谱、循环伏安法、密度泛函理论计算和空间电荷限制电流法对合成的 HTM 的光电、电化学、理论和电荷传输特性进行了表征。分别通过水接触角分析和原子力显微镜研究了 HTM 膜的疏水性和表面粗糙度。PSC 是用 HTM、非氟化对照分子和常用的螺-OMeTAD 在周围环境中制造的，没有封装。扫描电子显微镜用于获得钙钛矿层的形貌信息和器件的横截面图像。带有氟化 HTM 的器件表现出 13 的最佳 PCE。96%。在受控潮湿环境下的稳定性研究表明，与对照装置相比，氟化装置的水分稳定性有所提高，表明疏水性 HTM 成功地抑制了水分对钙钛矿结构的损伤。