Perovskites are known for their high yield photoluminescence and higher photovoltaic conversion efficiencies. To make them practically useful, the toxicity and stability issues need to be addressed. Herein, we report a less toxic and stable silver bismuth iodide quantum dot system, prepared by a modified ligand assisted reprecipitation (LARP) method. Three types of phase structures such as AgBiI 4 , Ag 2 BiI 5 , and AgBi 2 I 7 were obtained, and their structural and photophysical properties were investigated. By replacing lead (Pb), the toxicity would be reduced considerably and the optical properties persisted for more than six months at ambient conditions. The as-prepared silver bismuth iodide QDs were then used to construct photodetector devices, and the device performances were studied. The constructed photodetector devices have generated the photocurrent values of (AgBi 2 I 7 ∼ 0.12 and 0.32 mA), (Ag 2 BiI 5 ∼ 0.87 and 1.6 μA), and (AgBiI 4 ∼ 0.16 and 0.61 mA) at different biasing voltages of 0.1 and 0.2 V, respectively, under visible light irradiation. The AgBi 2 I 7 QD system generated higher photocurrent value and exhibited a better ON/OFF ratio of (I on /I off = 6.5 × 10 4 ). The silver bismuth iodide QDs based photodetectors are promising for ultraviolet photodetection.

Graphene has been studied intensively in opto-electronics, and its transport properties are well established. However, efforts to induce intrinsic optical properties are still in progress. Herein, we report the production of micron-sized sheets by interconnecting graphene quantum dots (GQDs), which are termed ‘GQD solid sheets’, with intrinsic absorption and emission properties. Since a GQD solid sheet is an interconnected QD system, it possesses the optical properties of GQDs. Metal atoms that interconnect the GQDs in the bottom-up hydrothermal growth process, induce the semiconducting behaviour in the GQD solid sheets. X-ray absorption measurements and quantum chemical calculations provide clear evidence for the metal-mediated growth process. The as-grown graphene quantum dot solids undergo a Forster Resonance Energy Transfer (FRET) interaction with GQDs to exhibit an unconventional 36% photoluminescence (PL) quantum yield in the blue region at 440 nm. A high-magnitude photocurrent was also induced in graphene quantum dot solid sheets by the energy transfer process.

The effect of Cs substitution in MA1−xCsxPbBr3 perovskites was explored using Raman spectroscopy and XRD to identify the microstructural evolution.

Here in, we report the formation of CdTe quantum dot interconnected solid nanowire network by a bottom up process. The as formed nanostructure, also, named as quantum dot solid structure has exhibited a high magnitude photocurrent value of 0.25 mA, corresponding to the biasing voltage of 1.5 V. The improved photocurrent generation is a consequence of suppressed inter-dot charge transport resistance upon quantum solid nanowire network formation. This interesting network structure was further decorated with graphene quantum dots by optimizing the growth parameters. The hybrid nanostructure has shown a further enhancement in the photocurrent generation. Formation of such new nanostructures and their interesting photo-physical properties are discussed in detail.

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