Study on photoelectrical properties of Nb-MoS2, theoretically and experimentally

In this work, we adopted the method of doping Nb element to improve the photo response of MoS
₂
. The experiment results show the responsivity of the Nb-doped MoS
₂
sample is improved under red and purple light. When the wavelength is 650 nm and the bias voltage is 10 V, the photo responsivity of Nb-doped MoS
₂
sample is 65 mA/W, while that of the MoS
₂
sample is 0.05 mA/W. And this result can be explained by the higher absorbance of Nb-doped MoS
₂
than pure MoS
₂
calculated by first principles based on density functional theory. Besides, an interesting phenomenon has been discovered that at a voltage of less than 1V, the optical response of Nb-doped MoS
₂
is completely opposite.