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All inorganic quantum dot light emitting devices with solution processed transport layers are investigated. The device consists of an anode, a hole transport layer, a quantum dot emissive layer, an electron transport layer and a cathode. Indium tin oxide coated glass slides are used as substrates with the indium tin oxide acting as the transparent anode electrode. The transport layers are both inorganic, which are relatively insensitive to moisture and other environmental factors as compared to their organic counterparts. Nickel oxide acts as the hole transport layer, while zinc oxide nanocrystals act as the electron transport layer. The nickel oxide hole transport layer is formed by annealing a spin coated layer of nickel hydroxide sol-gel. On top of the hole transport layer, CdSe/ZnS quantum dots synthesized by hot injection method is spin coated. Finally, zinc oxide nanocrystals, dispersed in methanol, are spin coated over the quantum dot emissive layer as the electron transport layer. The material characterization of different layers is performed by using absorbance, Raman scattering, XRD, and photoluminescence measurements. The completed device performance is evaluated by measuring the IV characteristics, electroluminescence and quantum efficiency measurements. The device turn on is around 4V with a maximum current density of ∼200 mA/cm2 at 9 V.

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Inorganic perovskite photodetector with chromium interdigitated electrodes is investigated. The active material is a solution processed CsPbI3 synthesized by one step deposition. The α-phase of this material is unstable at room temperature and it converts to the δ-phase at temperatures below 320°C. The stabilization of the α-phase was conducted in nitrogen environment by adding 5% weight ratio of polyethylene oxide to the equimolar mixture of PbI2 and CsI in dimethyl sulfoxide. The absorbance spectrum of the CsPbI3 with polyethylene oxide showed the emergence of a second peak at ∼ 690 nm related to the α-phase in addition to the peak at 420 nm of the δ phase. The peak in the visible range was also observed in the μ-photoluminescence spectrum at 690 nm. The interdigital structure was prepared by photolithography method to deposit 80 nm of chromium interdigitated electrodes on glass substrate with 10 μm channel width. The detector's on/off ratio and the detectivity were calculated from the current voltage curve under 100 mW/cm2 to be 9.64×103 and 9.2×109 Jones respectively.

Photodetectors based on a hybrid structure of graphene sensitized with lead selenide (PbSe) colloidal quantum dots (QDs) effective in the near-infrared (NIR) region with high responsivity were investigated. Colloidal PbSe nanocrystals were synthesized via a hot injection method. The bandgap of the synthesized nanocrystals was determined to be 0.68 eV by measuring their optical absorbance spectrum. Photodetectors based on PbSe QDs were investigated to examine their functionality. These devices were characterized by measuring the current-voltage curves in the dark and light and the spectral response spectrum. A photodetector was fabricated using a multilayer mechanically exfoliated graphene on a Si/SiO2 substrate with a PbSe QDs layer on top. A responsivity and detectivity of 1265A/W and 3.4 *1010cm.Hz0.5/W respectively were calculated based on current-voltage measurements.