In Situ Surface Sulfidation of CsPbI3 for Inverted Perovskite Solar Cells

作者：Guo, Xuemin; Lu, Chunyan; Zhang, Wenxiao; Yuan, Haobo; Yang, Hui; Liu, Acan; Cui, Zhengbo; Li, Wen; Hu, Yuyang; Li, Xiaodong^*; Fang, Junfeng^*

来源：ACS Energy Letters, 2024, 9(1): 329-335.

DOI：10.1021/acsenergylett.3c01855

• DEFECT PASSIVATION
• EFFICIENT

Inverted CsPbI3 commonly exhibits a more p-type surface than bulk, which induces severe interfacial recombination and, thus, limits the device's V-oc and efficiency in inverted perovskite solar cells (PSCs). Here, a gradual CsPbI3/PbS heterojunction is constructed to inhibit such recombination through in situ chemical sulfidation with N,N '-diphenylthiourea (DPhTA). DPhTA can directly react with CsPbI3 to form PbS and induce a p- to n-type transition at the CsPbI3 surface, which leads to the energy level bending downward and establishing a gradual CsPbI3/PbS heterojunction at the top of the surface region. PSCs with DPhTA exhibit a high V-oc of 1.20 V and reach over 20% efficiency (stabilized efficiency of 19.5%), which is among the highest efficiencies of inverted CsPbI3 PSCs. In addition, the strong Pb-S bond and well-matched crystal lattice of PbS will protect and stabilize the CsPbI3 layer beneath, thereby greatly improving the device's stability. Resulting PSCs retain over 95% of the initial efficiency whether after maximum power point (MPP) tracking for 1200 h or N-2 storage for 300 days.