Fluorine Functionalized Graphene Nano Platelets for Highly Stable Inverted Perovskite Solar Cells

• Published in: Nano letters Vol. 17; no. 10; pp. 6385 - 6390
• Main Authors: Kim, Gi-Hwan, Jang, Hyungsu, Yoon, Yung Jin, Jeong, Jaeki, Park, Song Yi, Walker, Bright, Jeon, In-Yup, Jo, Yimhyun, Yoon, Hyun, Kim, Minjin, Baek, Jong-Beom, Kim, Dong Suk, Kim, Jin Young
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 11.10.2017
• Subjects: functionalized graphene; hydrophobic; stability; graphene; Perovskite solar cells; p−i−n
• ISSN: 1530-6984; 1530-6992; 1530-6992
• DOI: 10.1021/acs.nanolett.7b03225

Edged-selectively fluorine (F) functionalized graphene nanoplatelets (EFGnPs-F) with a p–i–n structure of perovskite solar cells achieved 82% stability relative to initial performance over 30 days of air exposure without encapsulation. The enhanced stability stems from F-substitution on EFGnPs; fluorocarbons such as polytetrafluoroethylene are well-known for their superhydrophobic properties and being impervious to chemical degradation. These hydrophobic moieties tightly protect perovskite layers from air degradation. To directly compare the effect of similar hydrophilic graphene layers, edge-selectively hydrogen functionalized graphene nanoplatelet (EFGnPs-H) treated devices were tested under the same conditions. Like the pristine MAPbI3 perovskite devices, EFGnPs-H treated devices were completely degraded after 10 days. The hydrophobic properties of EFGnPs-F were characterized by contact angle measurement. The test results showed great water repellency compared to pristine perovskite films or EFGnPs-H coated films. This resulted in highly air-stable p–i–n perovskite solar cells.