Fig. 2

Effect of trap state on photocurrent and response speed. a For photoconductive detectors, the trap state in the material can cause persistent photocurrent (photoconductive gain) to improve the responsivity of the device, but at the same time the response speed will be slowed down. b Photoconductivity detectors based on materials without trap state do not generate persistent photocurrent, but they can achieve a faster response speed. c For photovoltaic detectors, the trap state in the material can simultaneously reduce the photocurrent and response speed of the device. d Photovoltaic detectors based on materials without trap state can achieve high photocurrent and fast response speed at the same time