Shin Gwang Su, Zhang Yong, Park Nam-Gyu
School of Chemical Engineering, Sungkyunkwan University, Suwon 16419, Korea.
ACS Appl Mater Interfaces. 2020 Apr 1;12(13):15167-15174. doi: 10.1021/acsami.9b23086. Epub 2020 Mar 20.
We report here on the stability of a precursor solution for perovskite solar cells. Solution was aged at ambient conditions for 4 weeks, where two different precursor solutions were prepared by dissolving FAI and PbI in DMSO/DMF solvent (precursor mixture solution) and the synthesized single crystalline α-FAPbI in the same solvent (single crystal solution). Perovskite films were prepared by depositing fresh or aged solutions at weekly intervals. Photovoltaic parameters were hardly altered by aging the single crystal solution, while power conversion efficiency was gradually decreased with aging time for the precursor mixture solution mainly due to the decreased photocurrent density and fill factor. Solution pH was changed from basic to acidic due to HI formed by aging the precursor mixture solution, which prevents the formation of α-phase of FAPbI. For the single crystal solution, basic conditions remained unchanged by aging. In addition, the presence of δ-phase in the annealed perovskite films was found to have negative influence on the long-term stability. It is thus important to maintain the pH of the precursor solution to avoid aging effects and remove δ-phase in the annealed film for device stability.
我们在此报告钙钛矿太阳能电池前驱体溶液的稳定性。溶液在环境条件下老化4周，其中通过将FAI和PbI溶解在DMSO/DMF溶剂中制备两种不同的前驱体溶液（前驱体混合溶液），并在相同溶剂中合成单晶α-FAPbI（单晶溶液）。通过每周间隔沉积新鲜或老化的溶液来制备钙钛矿薄膜。老化单晶溶液对光伏参数几乎没有影响，而前驱体混合溶液的功率转换效率随老化时间逐渐降低，这主要是由于光电流密度和填充因子降低。由于老化前驱体混合溶液形成的HI，溶液pH从碱性变为酸性，这阻止了FAPbIα相的形成。对于单晶溶液，老化后碱性条件保持不变。此外，发现退火钙钛矿薄膜中δ相的存在对长期稳定性有负面影响。因此，保持前驱体溶液的pH值以避免老化影响并去除退火薄膜中的δ相对于器件稳定性很重要。
