Conventional Cu(In,Ga)Se (CIGS) solar cells exhibit poor spectral response due to parasitic light absorption in the window and buffer layers at the short wavelength range between 300 and 520 nm. In this study, the CdSe/CdZnS core/shell quantum dots (QDs) acting as a luminescent down-shifting (LDS) layer were inserted between the MgF antireflection coating and the window layer of the CIGS solar cell to improve light harvesting in the short wavelength range. The LDS layer absorbs photons in the short wavelength range and re-emits photons in the 609 nm range, which are transmitted through the window and buffer layer and absorbed in the CIGS layer. The average external quantum efficiency in the parasitic light absorption region (300-520 nm) was enhanced by 51%. The resulting short circuit current density of 34.04 mA/cm and power conversion efficiency of 14.29% of the CIGS solar cell with the CdSe/CdZnS QDs were improved by 4.35 and 3.85%, respectively, compared with those of the conventional solar cells without QDs.

No abstract

A synaptic device that functionally mimics a biological synapse is a promising candidate for use as an electronic element in a neuromorphic system. In this study, flexible electronic synaptic devices based on poly (methyl methacrylate) (PMMA):CdSe/CdZnS core-shell quantum-dot (QD) nanocomposites are demonstrated. The current-voltage characteristics for the synaptic devices under consecutive voltage sweeps show clockwise hysteresis, which is a critical feature of an artificial synaptic device. The effect of the CdSe/CdZnS QD concentration on the device performance is studied. The flexible electronic synaptic devices under bending show the similar and stable electrical performances. The memory retention measurements show that the e-synapse exhibits long-term potentiation and depression. The carrier transport mechanisms are analyzed, and thermionic emission and space-charge-limited-current conduction are found to be dominant.

No abstract

No abstract