多功能钾盐调控SnO2/钙钛矿埋底界面实现高效稳定钙钛矿太阳能电池

Multifunctional Potassium Salt Regulation of SnO2/Perovskite Buried Bottom Interface to Achieve Efficient and Stable Perovskite Solar Cells

摘要:

目前，钙钛矿太阳能电池是能源领域中的新兴产业，其在飞速发展的同时遇到了瓶颈，如层状三明治结构导致严重的界面问题。因此，提高界面传输特性是提高钙钛矿太阳能电池稳定性及光电转换效率（PCE）的关键步骤。界面修饰或界面钝化是实现高质量界面电荷传输的一种简单、高效的手段。由于柠檬酸钾（PC）具有多钝化点位，其作为一种高效、简单的多功能小分子被引入到正置钙钛矿太阳能电池电子传输层二氧化锡（SnO₂）/钙钛矿界面中，以优化电池中存在的界面问题。PC的引入不仅与电子传输层SnO₂表面有害的羟基发生反应以预防水分入侵，还能与钙钛矿层下表面作为深能级缺陷及非辐射复合中心的游离铅离子配位，有效减少薄膜的缺陷态密度，抑制不理想的非辐射复合，提高薄膜结晶质量。迟滞效应与太阳能电池的光电转换性能有关，其会导致电池在不同光照条件下的性能表现不同。钾离子的引入可大幅降低器件的迟滞效应，提高电池运行的复现性。基于PC对埋底界面的修饰，正置钙钛矿太阳能电池的光电转换效率从初始的21.33%提高到了24.29%。除此以外，相比原始组不足300 h的湿度稳定性，目标组未封装器件在50%±5%的湿度环境下老化675 h后仍保持81%的初始效率。多功能钾盐调控SnO₂/钙钛矿埋底界面，为高效稳定钙钛矿太阳能电池的开发提供了理论基础。

Abstract:

Perovskite solar cells are an emerging industry in today's energy development， but they have also encountered bottlenecks in their rapid development. The layered sandwich structure of solar cellsinevitably brings serious interface problems. Therefore， improving the interface transmission characteristics is a key step in improving the stability and photoelectric conversion efficiency （PCE） of perovskite solar cells. Interface modification or passivation is a simple and efficient means of achieving high-quality interface charge transfer. Here， potassium citrate （PC）， due to its multiple passivation sites， is introduced as an efficient and simple multifunctional small molecule into the interface of tin dioxide （SnO₂）/perovskite in the electron transport layer of upright perovskite solar cells to optimize the interface problems in the solar cell. Firstly， the introduction of PC not only reacts with harmful hydroxyl groups on the surface of SnO₂ in the electron transport layer， but also prevents water intrusion； It also coordinates with free lead ions on the lower surface of the perovskite layer as deep level defects and non-radiative recombination centers， effectively reducing the defect state density of the thin film， suppressing unsatisfactory non radiative recombination， and thus improving the crystallization quality of the thin film； Secondly， the hysteresis effect is also related to the photovoltaic conversion performance of solar cells， which can lead to performance variations under different lighting conditions. The introduction of potassium ions significantly reduces device hysteresis and improves the reproducibility of battery operation. Based on the modification of the buried interface by PC， the photoelectric conversion efficiency of the upright perovskite solar cell increased from the initial 21.33% to 24.29%. In addition， compared to the humidity stability of the control group for less than 300 h， the unpackaged devices in the target group maintained an initial efficiency of 81% after aging for 675 h in a humidity environment of 50%±5%. This work provides a theoretical basis for the development of efficient and stable perovskite solar cells.