Adam Ibrahim Muhammad, Soe Kay Thi, Ruengsrisang Waranchit, Ketsombun Ekkaphop, Supasai Thidarat, Sutthibutpong Thana, Rujisamphan Nopporn, Thongprong Non
Nanoscience and Nanotechnology Graduate Program, Faculty of Science, King Mongkut's University of Technology Thonburi, Bangkok 10140, Thailand.
Department of Physics, Faculty of Science, King Mongkut's University of Technology Thonburi, Bangkok 10140, Thailand.
ACS Appl Mater Interfaces. 2025 May 28;17(21):31000-31012. doi: 10.1021/acsami.5c04415. Epub 2025 May 14.
Tin(IV) oxide (SnO) is a promising electron transport layer for n-i-p perovskite solar cells (PSCs) due to its high transmittance, excellent charge mobility, and strong chemical stability. However, surface defects such as oxygen vacancies and hydroxyl groups at the SnO/perovskite interface degrade the device performance by increasing carrier recombination and accelerating degradation. While alkali halide salts offer a simple yet effective method for passivation, their enhancement mechanisms at the atomic level remain unclear, as most studies focus on bulk or surface effects rather than the heterointerface itself. Here, we introduce a potassium halide salt (PHS: KI, KCl, and KI+KCl) post-treatment to passivate the SnO/MAPbI interface. Our combined experimental and density functional theory (DFT) analyses demonstrate that K and halide ions facilitate the removal of oxygen vacancies and extrinsic hydroxyl groups through the formation of KOH. This process effectively reduces the bond strength of surface hydroxyls and enhances interfacial ordering. This results in a smoother interface, larger perovskite grain sizes, improved adhesion, and enhanced charge extraction. The formation of Sn-Cl-Pb and Sn-I-Pb bonds, along with electrostatic interactions among interfacial K, I in the perovskite structure, and O in SnO, strengthens the interface and reduces ion migration. KI-modified and mixed KI+KCl devices achieved power conversion efficiencies (PCEs) of 19.86% and 19.15%, respectively, outperforming untreated SnO, which had a PCE of 18.41%. More importantly, the mixed KI+KCl treatment shows superior stability improvement compared to individual PHS treatments, retaining over 96% of the initial PCE after 1000 h under 40-50% relative humidity. These findings highlight the critical role of potassium salts in improving both efficiency and stability, offering an effective strategy for advancing PSC technology.
二氧化锡（SnO₂）因其高透光率、优异的电荷迁移率和强大的化学稳定性，是用于n-i-p钙钛矿太阳能电池（PSC）的一种很有前景的电子传输层。然而，SnO₂/钙钛矿界面处的表面缺陷，如氧空位和羟基，会通过增加载流子复合和加速降解来降低器件性能。虽然碱金属卤化物盐提供了一种简单而有效的钝化方法，但其在原子水平上的增强机制仍不清楚，因为大多数研究集中在体相或表面效应而非异质界面本身。在此，我们引入卤化钾盐（PHS：KI、KCl以及KI+KCl）后处理来钝化SnO₂/MAPbI界面。我们结合实验和密度泛函理论（DFT）分析表明，K⁺和卤离子通过形成KOH促进氧空位和外在羟基的去除。这一过程有效降低了表面羟基的键强并增强了界面有序性。这导致界面更平滑、钙钛矿晶粒尺寸更大、附着力提高以及电荷提取增强。Sn-Cl-Pb和Sn-I-Pb键的形成，以及钙钛矿结构中界面K⁺、I⁻与SnO₂中O²⁻之间的静电相互作用，强化了界面并减少了离子迁移。KI修饰和KI+KCl混合器件的功率转换效率（PCE）分别达到了19.86%和19.15%，优于未处理的SnO₂器件，其PCE为18.41%。更重要的是，与单独的PHS处理相比，KI+KCl混合处理显示出卓越的稳定性提升，在40 - 50%相对湿度下1000小时后仍保留超过96%的初始PCE。这些发现突出了钾盐在提高效率和稳定性方面的关键作用，为推进PSC技术提供了一种有效策略。
