Lead sulfide (PbS) colloidal quantum dots (QDs) have received attentions as materials for near-infrared (NIR) photodetection in view of their strong and tunable absorption in the NIR region and room-temperature solution processability. However, the realization of high-speed PbS QD photodetection has been severely hindered by the extremely low carrier mobility (∼10 −5 to 10 −2 cm 2 V −1 s −1 ). Here, an ultrafast PbS QD photodiode fabricated with low mobility QDs (∼10 −3 cm 2 V −1 s −1 ) is demonstrated, which has rise/fall times as short as 0.33 μs at zero voltage bias. The fast response is achieved by engineering resistor−capacitor (RC) time delay and charge transport in the device. The photodiode also has an external quantum efficiency (EQE) exceeding 100% under voltage bias, which is possibly due to the photoconductive gain induced by hole transport layer (HTL). The photoconductive gain combined with low noise current enables high sensitivity with a specific detectivity value up to 3.2 × 10 11 Jones at 1125 nm.

Low-dimensional semiconductor nanostructures are of great interest in high performance electronic and photonic devices. ZnO is considered to be a multifunctional material due to its unique properties with potential in various applications. In this work, 3-nm ZnO nanoislands are deposited by Atomic Layer Deposition (ALD) and the electronic properties are characterized by UV-Vis-NIR Spectrophotometer and X-ray Photoelectron Spectroscopy. The results show that the nanostructures show quantum confinement effects in 1D. Moreover, Metal-Oxide-Semiconductor Capacitor (MOSCAP) charge trapping memory devices with ZnO nanoislands charge storage layer are fabricated by a single ALD step and their performances are analyzed. The devices showed a large memory window at low operating voltages with excellent retention and endurance characteristics due to the additional oxygen vacancies in the nanoislands and the deep barrier for the trapped holes due to the reduction in ZnO electron affinity. The results show that the ZnO nanoislands are promising in future low power memory applications.

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We report the use of an ecofriendly and recyclable CNC material as the host matrix for luminescent solar concentrator applications.