Mahdi Samadi Khoshkhoo

Technische Universität Dresden | TUD · Chair of Materials Science and Nanotechnology

Nanocrystal micro/nanoarrays with multiplexed functionalities are of broad interest in the field of nanophotonics, cellular dynamics, and biosensing due to their tunable electrical and optical properties. This work focuses on the multicolor patterning of two-dimensional nanoplatelets (NPLs) via two sequential self-assembly and direct electron-beam...

We report on a near-infrared (NIR) emitting semiconductor nanocrystal (NC) heterostructure with tunable optical properties. This heterostructure is built of two different semiconductor sections in the same NC combining various absorption/emission properties of each constituent part. In our approach, PbSe NCs of different sizes are grown on the tips...

We report a synthesis route to two-dimensional PbSe, HgSe, ZnSe, SnSe, and Cu–Zn–Sn–Se (CZTSe) nanomaterials based on cation exchange (CE) reactions. This approach includes two steps: it starts with the...

Investigation of the influence of the nanocrystal (NC) surface chemistry on the (opto)electronic properties of NCs-based thin-films is of paramount importance for their further application in various devices. In this work, macroscopic superlattices of copper selenide (Cu2‒xSe) NCs in the form of thin films were prepared by self-assembly at the liqu...

Quasi-two-dimensional (2D) CdSe nanoplatelets (NPLs) are distinguished by their unique optical properties in comparison to classical semiconductor nanocrystals (NCs), such as extremely narrow emission line widths, reduced Auger recombination, and relatively high absorption cross sections. Inherent to their anisotropic 2D-structure, however, is the...

In this work, we present a new synthetic approach to colloidal PbS nanoplatelets (NPLs) utilizing a cation exchange (CE) strategy starting from CuS NPLs synthesized via the hot-injection method. Whereas the thickness of the resulting CuS NPLs was fixed at approx. 5 nm, the lateral size could be tuned by varying the reaction conditions, such as time...

In this work, we report a colloidal synthesis of atomically flat colloidal PbSe nanoplatelets (NPLs) of different thicknesses from 3 to 6 monolayers via cation exchange from the corresponding CdSe NPLs. In order to preserve the delicate structure of the NPLs, we performed the reaction at mild conditions using a temperature of 80°C and lead bromide...

Indium-Tin-Oxide (ITO) nanoparticles have been cross-linked with organic 1,8-Diaminooctane (C8A) molecules. The network has been prepared by layer-by-layer self-assembly on substrates with interdigitated electrodes and their sensing properties were studied with vapors of toluene, 1-propanol, water, and 4-methyl-2-pentanone. We demonstrated that the...

Macroscopic superlattices of tin-doped indium oxide (ITO) nanocrystals (NCs) are prepared by self-assembly at the air/liquid interface followed by simultaneous ligand exchange with the organic semiconductors M-4,4′,4″,4″′-tetraaminophthalocyanine (M4APc, M = Cu, Co, Fe, Ni, Zn). Transport measurements, focusing on the effect of the metal center of...

We introduce extensions to a recently developed numerical model to understand the origin of universal Fermi level pinning of perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) and its underlying mechanism. Our calculations are supported by ultraviolet and X-ray photoelectron spectroscopy to investigate the electronic structure of PTCDA on a wide...

Macroscopic superlattices of tin-doped indium oxide (ITO) nanocrystals (NCs) are prepared by self-assembly at the air/liquid interface followed by simultaneous ligand exchange with the organic semiconductor Cu-4,4`,4``,4```-tetraaminophthalocyanine (Cu4APc). By using X-ray photoelectron spectroscopy (XPS), grazing-incidence small-angle X-ray scatte...

We simultaneously surface-functionalize PbS nanocrystals with Cu 4,4',4'',4'''-tetraaminophthalocyanine and assemble this hybrid material into macroscopic monolayers. Electron microscopy and X-ray scattering reveal a granular mesocrystalline structure with strong coherence between the atomic lattice and the superlattice of nanocrystals within each...

The rise of two-dimensional (2D) graphene-cognated crystals with non-zero band gaps like transition metal dichalcogenides has led to a rapidly increasing interest in their dimensionality-dependent anisotropic properties, which bear high potential for ultrathin electronics. 2D crystals of the III-VI metal chalcogenide InSe represent a new kind of ma...

We use the photochromic organic semiconductor 1,2-Bis(5′-carboxy-2′-methylthien-3′-yl)-cyclopentene (DTCP) to cross-link PbS quantum dots assembled into thin films. The ligand exchange is monitored by means of vibrational spectroscopy (FT-IR) and core-level X-ray photoemission spectroscopy (XPS). Transport measurements in a field-effect transistor...

We use the organic semiconductor tetrathiafulvalene dicarboxylate (TTFDA) to assemble PbS nanocrystals into conductive mesocrystals. Density functional theory calculations predict a size-tunable, near-resonant alignment between the PbS 1Sh state and the TTFDA HOMO with the potential to form a conductive channel for holes. We test this hypothesis wi...

We have investigated CeTIn5 (T = Co, Rh, Ir) by temperature and angle-dependent X-ray photoemission spectroscopy. The Ce 3d core level has a very similar shape for all three materials and is indicative of weak f-hybridization. The spectra have been analyzed using a simplified version of the Anderson Impurity model, which yields a Ce 4f occupancy th...

In this study, spherical polystyrene (PS) nanoparticles having a negative surface charge were synthesized by polymerization of a miniemulsion containing styrene monomer, normal hexadecane (HD) as hydrophobic agent, sodium dodecyl sulfate (SDS) as anionic emulsifier, sodium bicarbonate (NaHCO3) as buffer, and water soluble potassium persulfate (KPS)...