Developing a high response and low hysteresis humidity sensor based on C60-Lys

Unique electrical properties and chemical modifiability make fullerenes convenient for the fabrication of various measurement devices. In this paper, the fullerene derivative, C 60 -Lys, with abundant –OH,-NH 2 , and -COONa, has been creatively used to obtain a humidity sensor with high response (ΔI/I ≈ 2000) and low hysteresis (ΔH≈2.9% RH). The response time and recovery time of the C 60 -Lys sensor reach 24s and 29s respectively in the range of 11–97% relative humidity (RH). Hydrogen bonding and van der Waals forces between fullerene derivatives and water molecules play an important role in the adsorption and desorption of water molecules while the formation of ions causes rapid changes in the impedance of the C 60 -Lys sensor. It is worth noting that the device has excellent reproducibility and stability. These indicate it is a very good strategy to synthesize new humidity sensing materials by modifying groups on fullerenes to change the hydrophilicity of the surface.