Figure 3.

(a) Normalized photoresponse decay of a CdSe core NPL decorated graphene channel under various gas environments. Except for the measure under a moist air flow, the curves represent the current decay just after shutting the laser off under secondary vacuum (dark) and ambient air (red). As no photoresponse is measured under moist air flow, in this case the curve represents the photocurrent decay just after turning on the moist air flow (green). For all measurements, the curves are normalized by the photocurrent. (b) Proposed mechanism for electron transfer to graphene and water-assisted hole trapping for CdSe core and CdSe/CdS core/shell NPL decorated graphene upon illumination. (c) Proposed mechanism and associated transfer rates for the exciton dissociation, charge transfer to graphene and water-assisted hole trapping for CdSe-CdTe core-crown NPL decorated graphene. (b,c) k_Abs: exciton generation rate; k_Rec: exciton recombination rate; k_CT−e/h: electron/hole charge transfer rate to graphene; k_De−trap: water-assisted hole de-trapping rate; k_Diss: exciton dissociation rate (core-crown NPL only).