Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences , Ningbo 315201 , People's Republic of China.
University of Chinese Academy of Sciences , Beijing 100049 , People's Republic of China.
ACS Appl Mater Interfaces. 2019 Oct 9;11(40):36727-36734. doi: 10.1021/acsami.9b11817. Epub 2019 Sep 26.
Tin oxide (SnO) is widely used in perovskite solar cells (PSCs) as an electron transport layer (ETL) material. However, its high surface trap density has already become a strong factor limiting PSC development. In this work, phosphoric acid is adopted to eliminate the SnO surface dangling bonds to increase electron collection efficiency. The phosphorus mainly exists at the boundaries in the form of chained phosphate groups, bonding with which more than 47.9% of Sn dangling bonds are eliminated. The reduction of surface trap states depresses the electron transport barriers, thus the electron mobility increases about 3 times when the concentration of phosphoric acid is optimized with 7.4 atom % in the SnO precursor. Furthermore, the stability of the perovskite layer deposited on the phosphate-passivated SnO (P-SnO) ETL is gradually improved with an increase of the concentration. Due to the higher electron collection efficiency, the P-SnO ETLs can dramatically promote the power conversion efficiency (PCE) of the PSCs. As a result, the champion PSC has a PCE of 21.02%. Therefore, it has been proved that this simple method is efficient to improve the quality of ETL for high-performance PSCs.
氧化锡（SnO）作为电子传输层（ETL）材料，被广泛应用于钙钛矿太阳能电池（PSCs）。然而，其高表面悬挂键密度已成为限制 PSCs 发展的一个重要因素。在这项工作中，采用磷酸消除 SnO 表面悬挂键，提高电子收集效率。磷主要以链状磷酸基团的形式存在于边界处，与超过 47.9%的 Sn 悬挂键结合，消除了这些悬挂键。表面陷阱态的减少降低了电子输运势垒，因此当磷酸浓度优化为 SnO 前驱体中 7.4 原子%时，电子迁移率提高了约 3 倍。此外，随着浓度的增加，沉积在磷酸盐钝化 SnO（P-SnO）ETL 上的钙钛矿层的稳定性逐渐提高。由于更高的电子收集效率，P-SnO ETL 可显著提高 PSCs 的功率转换效率（PCE）。结果，冠军 PSC 的 PCE 达到了 21.02%。因此，事实证明，这种简单的方法可以有效地提高高性能 PSCs 的 ETL 质量。
