Muhammad Shehzad Sultan1,Wojciech Jadwisienczak2,Alejandra P Flores Rivera1,Brad Weiner1,Gerardo Morell1
University of Puerto Rico at Río Piedras1,Ohio University2
Muhammad Shehzad Sultan1,Wojciech Jadwisienczak2,Alejandra P Flores Rivera1,Brad Weiner1,Gerardo Morell1
University of Puerto Rico at Río Piedras1,Ohio University2
Nitrogen doped graphene quantum dots (GQDs) have been widely used for various optoelectronic devices as a photoactive material due to their high absorption coefficient and tunable bandgap. However, the low mobility of NGQD films results in poor charge collection and device performance. By combining NGQDs with graphene into hybrid NGQD/Graphene photodetectors, photocarriers from NGQDs are transferred to graphene, improving charge collection and transport, and drastically increasing the photoresponsivity. In this study, we report the preparation of a NGQD/Graphene heterostructure in order to investigate the effect of NGQD on the photoactive response of graphene. Using UV–vis absorption and photoluminescence (PL) spectra, the optical properties of NGQD/Graphene heterostructure were measured. Moreover, to investigate their electronic and charge transfer properties, we fabricated the photodetectors with pristine graphene quantum dots and NGQD/Graphene heterostructure to analyze and compare their photoactive electrical properties. Under illumination, NGQD/Graphene PD showed an increase in both current and carrier mobility as compared to NGQD PD. The increased current and carrier mobility of NGQD/Graphene PD is due to the presence of a large number of photoexcited charge carriers. This is explained by NGQDs' n-type doping effect on graphene, which reduces the accumulation of holes in the active p-channel near the insulating layer and causes charge to be transferred from the NGQDs to the graphene. As a result, we discovered a charge transfer effect in the NGQD/Graphene heterostructure, which could be used in optoelectronic devices.