Lithium-Ion Endohedral Fullerene (Li+@C60) Dopants in Stable Perovskite Solar Cells Induce Anti-Oxidation
Dr. Il Jeon,Dr. Hiroshi Ueno,Seungju Seo,Dr. Kerttu Aitola,Ryosuke Nishikubo,Prof. Akinori Saeki,Dr. Hiroshi Okada,Prof. Gerrit Boschloo,Prof. Shigeo Maruyama,Prof. Yutaka Matsuo
Herein, we report use of [Li+@C60]TFSI− as a dopant for spiro-MeOTAD in lead halide perovskite solar cells. This approach gave an air stability nearly 10-fold that of conventional devices using Li+TFSI−. Such high stability is attributed to the hydrophobic nature of [Li+@C60]TFSI− repelling moisture and absorbing intruding oxygen, thereby protecting the perovskite device from degradation. Furthermore, [Li+@C60]TFSI− could oxidize spiro-MeOTAD without the need for oxygen. The encapsulated devices exhibited outstanding air stability for more than 1000 h while illuminated under ambient conditions.