The charge transport mechanism of a photodiode made of silver sulfide quantum dots decorated graphene for selective detection of blue light

A novel photodiode made of silver sulfide quantum dots decorated graphene was developed for the first time for the selective detection of blue light. The process of the decoration of graphene surface with silver sulfide quantum dots was performed through the synthesis of Ag2S QDs in the presence of graphene solution via polyol technique. The X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy and energy dispersive electron diffraction spectroscopy confirmed the successful decoration of graphene surface with Ag2S QDs. The high-resolution transmission electron microscopy revealed that the Ag2S QDs were distributed uniformly on the graphene surface and the average diameter of these QDs was around 8 ± 2 nm. The optical absorption measurements comprises that the decoration of graphene with Ag2S QDs leads to a red shift of the spectrum and an increase of the optical absorption by two times. The luminescence measurements revealed that the decoration of graphene with Ag2S QDs led to a decrease of the luminescence intensity, implying the efficient separations of electrons and holes. The photo-electrical properties indicated that the Ag2S QDs decorated graphene exhibited photodiode like behavior with high response to blue light. The luminescence intensity exhibited a linear regression against the photocurrent up to 5 lx. Therefore, the developed photodiode showed a promising potential to be employed as efficient selective photodiode for blue light.