Properties of Self-Assembled Hybrid Organic Molecule/Quantum Dot Multilayered Structures

Abstract

Hybrid nanostructures are attractive for future use in a variety of electronic components. Self-assembled hybrid organic/nanocrystals can couple quantum properties to semiconductor working devices and modify their functionality. For example, light absorption in some core quantum dot (QD)-based self-assembled detectors induces a large dipole. These dipole moments may change the current of a shallow field effect transistor on which the QDs’ layer is assembled. In order to improve the absorption and quantum efficiency of such devices, multiple self-assembled layers are used. In such layers the charge transfer, excitonic energy transfer, surface trap passivation, and oxidation mechanisms are not fully understood. Therefore, establishing new tools for characterizing multilayer devices is essential. In the present work we have used confocal fluorescence microscopy to examine the photophysical properties of multilayered self-assembled organic molecules and QDs. We studied the interlayer coupling and surface-related mechanisms. By changing the coupling molecules and using photoinduced processes that gradually change the system, we were able to compare different binding groups and molecules under different conditions. Importantly, we found that in layered structures the binding group greatly contribute to the electronic coupling and luminescence, a contribution stronger than the linker’s molecular length. Consequently, we propose that proper illumination of core QD-based detectors be used for activation and yield improvement.

Room-Temperature Inter-Dot Coherent Dynamics in Multilayer Quantum Dot Materials

“…The samples have been prepared, as described in refs. , Briefly, colloidal CdSe QDs of two different sizes were first synthesized, as described in ref : smaller QDs with a mean diameter of about 2.8 nm (“small” QD, S-QD) and larger ones with a mean diameter of 3.5 nm (“big” QD, B-QD). Covalent links between dots have been promoted using 1,3-propanedithiol (PDT), having a nominal length of 0.55 nm.…”

Room Temperature Inter-Dot Coherent Dynamics in Multilayers Quantum Dot Materials

“…The samples have been prepared as described in ref. [20][21][22] . Briefly, colloidal CdSe QDs of two different sizes were first synthesized as in ref.…”

“…In both films, the QD to QD average distance has been controlled using a short organic linker, 1,3-propanedithiol (PDT, nominal length 0.55 nm), which promoted the formation of inter-dot covalent couplings. [20][21][22] The assemblies included disordered multilayers prepared by alternately dipping fused silica substrates into a QDs' solution and a dithiol solution. Further details about the preparation of the samples and their morphological characterization can be found in the Methods Section below and in the Supplementary Information (SI).…”

Spin-Exciton Delocalization Enhancement in Multilayer Chiral Linker/Quantum Dot Structures

“…Using the wet chemistry methods described in previous works, ,, layer-by-layer adsorption was utilized to achieve an aggregated structure of CdSe dots covalently bound to l enantiomer α-helix 16-amino-acid chiral linkers (Figure a) that were 2.2 nm in length (see Methods).…”