Sudhakaran Shana, Madhavan Vinod E
Semiconductor and Optoelectronics Lab (SOL), Department of Materials Science and Engineering, National Institute of Technology Calicut, Kozhikode, Kerala 673601, India.
Langmuir. 2025 Jul 1;41(25):15841-15848. doi: 10.1021/acs.langmuir.5c00571. Epub 2025 Jun 13.
Perovskite solar cells (PSCs) have attracted much attention due to their potential to transform the photovoltaic industry with higher efficiency and lower material usage. However, their intrinsic instability under conditions such as moisture, light, and heat poses a significant obstacle to their growth, making them unsuitable for long-term use under ambient conditions. MAPbI is the most studied compound for PSC applications, however, the presence of Pb causes toxicity. Hybrid MAPbSnI is a potential replacement for this compound to reduce the toxicity concerns. In this study, MAPbI and MAPbSnI perovskites were designed and studied for their stability under ambient conditions with 60% RH (relative humidity). Various characterization techniques, including SEM, XRD, and UV-vis-NIR spectroscopy, were employed to analyze the structural, morphological, and optical properties of the films over 28 days. SEM analysis revealed that both MAPbI and MAPbSnI films underwent significant morphological alterations upon exposure to humid conditions. The initially well-defined grain shapes gradually degraded into porous structures with coarse surfaces over time. All of the samples formed well-defined tetragonal phases with distinct XRD peak intensities on the zeroth day. The XRD results indicated that MAPbI rapidly degraded into MAPbI·HO within 7 days of exposure. Even after 28 days, it existed as MAPbI·HO. UV-vis-NIR spectroscopy showed that the incorporation of Sn into the perovskite structure led to a red shift in the absorption edge and a slight reduction in the band gap, from 1.56 eV for MAPbI to 1.38 eV for MAPbSnI. The investigation of humidity-induced degradation in MAPbI and MAPbSnI perovskite thin films has yielded valuable insights into their stability and degradation mechanisms at 60% RH.
钙钛矿太阳能电池（PSCs）因其具有以更高效率和更低材料用量改变光伏产业的潜力而备受关注。然而，它们在诸如湿度、光照和热量等条件下的固有不稳定性对其发展构成了重大障碍，使其不适用于在环境条件下长期使用。MAPbI是用于PSC应用研究最多的化合物，然而，铅的存在会导致毒性。混合的MAPbSnI是该化合物的一种潜在替代品，可减少对毒性的担忧。在本研究中，设计并研究了MAPbI和MAPbSnI钙钛矿在60%相对湿度（RH）的环境条件下的稳定性。采用了各种表征技术，包括扫描电子显微镜（SEM）、X射线衍射（XRD）和紫外-可见-近红外光谱（UV-vis-NIR），以分析薄膜在28天内的结构、形态和光学性质。SEM分析表明，MAPbI和MAPbSnI薄膜在暴露于潮湿条件下时均发生了显著的形态变化。最初明确的晶粒形状随着时间的推移逐渐降解为具有粗糙表面的多孔结构。所有样品在第0天均形成了具有明显XRD峰强度的明确四方相。XRD结果表明，MAPbI在暴露7天内迅速降解为MAPbI·H₂O。即使在28天后，它仍以MAPbI·H₂O的形式存在。UV-vis-NIR光谱表明，将锡掺入钙钛矿结构中导致吸收边缘发生红移，带隙略有减小，从MAPbI的1.56电子伏特降至MAPbSnI的1.38电子伏特。对MAPbI和MAPbSnI钙钛矿薄膜中湿度诱导降解的研究为它们在60%RH下的稳定性和降解机制提供了有价值的见解。
