Yin Hao, Meng Weiwei, Guo Yuhan, Nie Zhiguo, Huang Yulan, Wang Gang, Wang Fei, Peng Shimin, Jiang Zegang, Hu Hanlin, Wu Bo, Xing Guichuan, Long Mingzhu
Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, P. R. China.
Institute of Applied Physics and Materials Engineering, University of Macau, Avenida da Universidade, Taipa, Macau, 999078, China.
Small. 2025 Jul 9:e2502285. doi: 10.1002/smll.202502285.
Ammonium cations are widely used for defect passivation in perovskite solar cells (PSCs), effectively reducing defect density and improving photovoltaic performance. However, ammonium cations tend to form 2D phases on the surface or at the grain boundaries of 3D perovskites, hindering charge transport across interfaces and between grains. Here, cyclohexylmethylammonium (CHMA), a low-polarity and low-rigidity alicyclic ammonium cation, is introduced to reduce intermolecular interactions among ammonium cations and improve their coordination with defect centers. In contrast, a structure-similar phenylethylammonium cation (PEA) with a conjugated π-bond system, higher polarity, and larger structure rigidity, exhibits strong intermolecular π-π interaction and facilitates the formation of quasi-2D phases via cation exchange. These quasi-2D phases exhibit non-uniform longitudinal distribution in the 3D perovskite layer, thereby compromising the charge extraction efficiency. The CHMA⁺-modified perovskite-based devices with p-i-n and n-i-p structures achieve impressive power conversion efficiencies of 25.66% (certified 24.64%) and 24.94%, respectively. Moreover, the device maintains over 95% of its initial efficiency after 1000 h of continuous operation under one-sun illumination at the maximum power point. These findings highlight the potential of rationally designing ammonium spacers to significantly improve both the efficiency and stability of PSCs.
铵阳离子被广泛用于钙钛矿太阳能电池（PSC）中的缺陷钝化，可有效降低缺陷密度并提高光伏性能。然而，铵阳离子倾向于在三维钙钛矿的表面或晶界处形成二维相，阻碍电荷在界面间和晶粒间的传输。在此，引入环己基甲基铵（CHMA），一种低极性和低刚性的脂环族铵阳离子，以减少铵阳离子之间的分子间相互作用，并改善它们与缺陷中心的配位。相比之下，具有共轭π键体系、更高极性和更大结构刚性的结构相似的苯乙铵阳离子（PEA），表现出强烈的分子间π-π相互作用，并通过阳离子交换促进准二维相的形成。这些准二维相在三维钙钛矿层中呈现不均匀的纵向分布，从而降低了电荷提取效率。具有p-i-n和n-i-p结构的CHMA⁺修饰的钙钛矿基器件分别实现了令人印象深刻的25.66%（认证值为24.64%）和24.94%的功率转换效率。此外，该器件在最大功率点的一个太阳光照下连续运行1000小时后，仍保持其初始效率的95%以上。这些发现突出了合理设计铵间隔基以显著提高PSC效率和稳定性的潜力。
