Maksym Yarema

Last Name

Yarema

First Name

Maksym

ORCID

0000-0002-2006-2466

Organisational unit

03895 - Wood, Vanessa / Wood, Vanessa

Show all metadata

Search Results

Publications 1 - 10 of 83

Highly Luminescent, Size- and Shape-Tunable Copper Indium Selenide Based Colloidal Nanocrystals
Yarema, Olesya; Bozyigit, Deniz; Rousseau, Ian; et al. (2013)
Chemistry of Materials
We report a simple, high-yield colloidal synthesis of copper indium selenide nanocrystals (CISe NCs) based on a silylamide-promoted approach. The silylamide anions increase the nucleation rate, which results in small-sized NCs exhibiting high luminescence and constant NC stoichiometry and crystal structure regardless of the NC size and shape. In particular, by systematically varying synthesis time and temperature, we show that the size of the CISe NCs can be precisely controlled to be between 2.7 and 7.9 nm with size distributions down to 9–10%. By introducing a specific concentration of silylamide-anions in the reaction mixture, the shape of CISe NCs can be preselected to be either spherical or tetrahedral. Optical properties of these CISe NCs span from the visible to near-infrared region with peak luminescence wavelengths of 700 to 1200 nm. The luminescence efficiency improves from 10 to 15% to record values of 50–60% by overcoating as-prepared CISe NCs with ZnSe or ZnS shells, highlighting their potential for applications such as biolabeling and solid state lighting.
Soft surfaces of nanomaterials enable strong phonon interactions
Bozyigit, Deniz; Yazdani, Nuri; Yarema, Maksym; et al. (2016)
Nature
R4Ir13Ge9 (R=La, Ce, Pr, Nd, Sm) and RIr3Ge2 (R=La, Ce, Pr, Nd)
Yarema, Maksym; Zaremba, O.; Gladyshevskii, R.; et al. (2012)
Journal of Solid State Chemistry
Solution-Processable Near-IR Photodetectors Based on Electron Transfer from PbS Nanocrystals to Fullerene Derivatives
Szendrei, Krisztina; Cordella, Fabrizio; Kovalenko, Maksym V.; et al. (2009)
Advanced Materials
Highly Monodisperse Bismuth Nanoparticles and Their Three-Dimensional Superlattices
Yarema, Maksym; Kovalenko, Maksym V.; Hesser, Guenter; et al. (2010)
Journal of the American Chemical Society
Charge transport in semiconductors assembled from nanocrystal quantum dots
Yazdani, Nuri; Andermatt, Samuel; Yarema, Maksym; et al. (2020)
Nature Communications
The potential of semiconductors assembled from nanocrystals has been demonstrated for a broad array of electronic and optoelectronic devices, including transistors, light emitting diodes, solar cells, photodetectors, thermoelectrics, and phase change memory cells. Despite the commercial success of nanocrystal quantum dots as optical absorbers and emitters, applications involving charge transport through nanocrystal semiconductors have eluded exploitation due to the inability to predictively control their electronic properties. Here, we perform large-scale, ab initio simulations to understand carrier transport, generation, and trapping in strongly confined nanocrystal quantum dot-based semiconductors from first principles. We use these findings to build a predictive model for charge transport in these materials, which we validate experimentally. Our insights provide a path for systematic engineering of these semiconductors, which in fact offer previously unexplored opportunities for tunability not achievable in other semiconductor systems.
Precision synthesis of colloidal inorganic nanocrystals using metal and metalloid amides
Yarema, Maksym; Caputo, Riccarda; Kovalenko, Maksym V. (2013)
Nanoscale
Phase-Controlled Synthesis and Phase-Change Properties of Colloidal Cu-Ge-Te Nanoparticles
Kumaar, Dhananjeya; Can, Matthias; Weigand, Helena; et al. (2024)
Chemistry of Materials
Phase-change memory (PCM) technology has recently attracted a vivid interest for neuromorphic applications, in-memory computing, and photonic integration due to the tunable refractive index and electrical conductivity between the amorphous and crystalline material states. Despite this, it is increasingly challenging to scale down the device dimensions of conventionally sputtered PCM memory arrays, restricting the implementation of PCM technology in mass applications such as consumer electronics. Here, we report the synthesis and structural study of sub-10 nm Cu-Ge-Te (CGT) nanoparticles as suitable candidates for low-cost and ultrasmall PCM devices. We show that our synthesis approach can accurately control the structure of the CGT colloids, such as composition-tuned CGT amorphous nanoparticles as well as crystalline CGT nanoparticles with trigonal alpha-GeTe and tetragonal Cu2GeTe3 phases. In situ characterization techniques such as high-temperature X-ray diffraction and X-ray absorption spectroscopy reveal that Cu doping in GeTe improves the thermal properties and amorphous phase stability of the nanoparticles, in addition to nanoscale effects, which enhance the nonvolatility characteristics of CGT nanoparticles even further. Moreover, we demonstrate the thin-film fabrication of CGT nanoparticles and characterize their optical properties with spectroscopic ellipsometry measurements. We reveal that CGT nanoparticle thin films exhibit a negative reflectivity change and have good reflectivity contrast in the near-IR spectrum. Our work promotes the possibility to use PCM in nanoparticle form for applications such as electro-optical switching devices, metalenses, reflectivity displays, and phase-change IR devices.
Recombination Dynamics in PbS Nanocrystal Quantum Dot Solar Cells Studied through Drift–Diffusion Simulations
Lin, Weyde; Yazdani, Nuri; Yarema, Olesya; et al. (2021)
ACS Applied Electronic Materials
The significant performance increase in nanocrystal (NC)-based solar cells over the last decade is very encouraging. However, many of these gains have been achieved by trial-and-error optimization, and a systematic understanding of what limits the device performance is lacking. In parallel, experimental and computational techniques provide increasing insights into the electronic properties of individual NCs and their assemblies in thin films. Here, we utilize these insights to parameterize drift–diffusion simulations of PbS NC solar cells, which enable us to track the distribution of charge carriers in the device and quantify recombination dynamics, which limit the device performance. We simulate both Schottky- and heterojunction-type devices and, through temperature-dependent measurements in the light and dark, experimentally validate the appropriateness of the parameterization. The results reveal that Schottky-type devices are limited by surface recombination between the PbS and aluminum contact, while heterojunction devices are currently limited by NC dopants and electronic defects in the PbS layer. The simulations highlight a number of opportunities for further performance enhancement, including the reduction of dopants in the nanocrystal active layer, the control over doping and electronic structure in electron- and hole-blocking layers (e.g., ZnO), and the optimization of the interfaces to improve the band alignment and reduce surface recombination. For example, reduction in the percentage of p-type NCs from the current 1–0.01% in the heterojunction device can lead to a 25% percent increase in the power conversion efficiency.
Spontaneous and reversible hollowing of alloy anode nanocrystals for stable battery cycling
Boebinger, Matthew G.; Yarema, Maksym; Unocic, Kinga A.; et al. (2020)
Nature Nanotechnology

Publications 1 - 10 of 83

Maksym Yarema

Last Name

First Name

ORCID

Organisational unit

Filters

Search Results