北京大学周欢萍团队报道了阴离子-π相互作用抑制FAPbI₃太阳能电池中的相杂质。相关研究成果于2023年10月18日发表于国际顶尖学术期刊《自然》。

实现高效率和长期稳定性是钙钛矿太阳能电池（PSCs）商业化的关键。然而，钙钛矿（ABX3）成分和相的多样性使得制备高质量的膜具有挑战性。钙钛矿的形成依赖于AX和BX2之间的反应，而大多数用于膜生长调节的常规方法仅基于与BX2组分的相互作用。

该文中，研究人员展示了一种通过AX和六氟苯（HFB）之间的阴离子-π相互作用调节反应动力学的替代方法。值得注意的是，这两种方法是独立的，但共同作用建立了“双位点调节”，在没有不想要的中间体的情况下实现了对AX和BX2之间反应的精细控制。所得到的甲脒-卤化铅（FAPbI₃）薄膜具有较少的缺陷、红移吸收和高相纯度，而没有可检测的纳米级δ相。因此，研究人员实现了功率转换效率（PCE）高达26.07%（0.08-cm²器件）和24.63%（1-cm²器件）的PSCs。在50±5°C的全光谱AM1.5G阳光下，最大功率点（MPP）跟踪1258h后，该设备还保持了94%的初始PCE。

该方法通过探索阴离子-π相互作用，扩大了钙钛矿前体中发生的化学相互作用的范围，并强调了AX组分作为一种新的有效工作场所对改进高质量和相纯度光伏器件的重要性。

附：英文原文

Title: Anion–π interactions suppress phase impurities in FAPbI3 solar cells

Author: Huang, Zijian, Bai, Yang, Huang, Xudan, Li, Jiatong, Wu, Yuetong, Chen, Yihua, Li, Kailin, Niu, Xiuxiu, Li, Nengxu, Liu, Guilin, Zhang, Yu, Zai, Huachao, Chen, Qi, Lei, Ting, Wang, Lifen, Zhou, Huanping

Issue&Volume: 2023-10-18

Abstract: Achieving both high efficiency and long-term stability is the key to the commercialization of perovskite solar cells (PSCs)1,2. However, the diversity of perovskite (ABX3) compositions and phases makes it challenging to fabricate high-quality films3,4,5. Perovskite formation relies on the reaction between AX and BX2, whereas most conventional methods for film-growth regulation are based solely on the interaction with the BX2 component. Herein, we demonstrate an alternative approach to modulate reaction kinetics by anion–π interaction between AX and hexafluorobenzene (HFB). Notably, these two approaches are independent but work together to establish ‘dual-site regulation’, which achieves a delicate control over the reaction between AX and BX2 without unwanted intermediates. The resultant formamidinium lead halides (FAPbI3) films exhibit fewer defects, redshifted absorption and high phase purity without detectable nanoscale δ phase. Consequently, we achieved PSCs with power conversion efficiency (PCE) up to 26.07% for a 0.08-cm2 device (25.8% certified) and 24.63% for a 1-cm2 device. The device also kept 94% of its initial PCE after maximum power point (MPP) tracking for 1,258h under full-spectrum AM1.5G sunlight at 50±5°C. This method expands the range of chemical interactions that occur in perovskite precursors by exploring anion–π interactions and highlights the importance of the AX component as a new and effective working site to improved photovoltaic devices with high quality and phase purity.

DOI: 10.1038/s41586-023-06637-w

Source: https://www.nature.com/articles/s41586-023-06637-w