Browsing by Author "Guzelturk, B."
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Amplified Spontaneous Emission and Lasing in Colloidal Nanoplatelets
Guzelturk, B.; Kelestemur, Y.; Olutas, M.; Delikanli, S.; Demir, Hilmi Volkan (American Chemical Society, 2014-07)Colloidal nanoplatelets (NPLs) have recently emerged as favorable light-emitting materials, which also show great potential as optical gain media due to their remarkable optical properties. In this work, we systematically ... -
Attractive versus repulsive excitonic interactions of colloidal quantum dots control blue-to red-shifting (and non-shifting) amplified spontaneous emission
Cihan, A. F.; Kelestemur, Y.; Guzelturk, B.; Yerli, O.; Kurum, U.; Yaglioglu, H. G.; Elmali, A.; Demir, Hilmi Volkan (American Chemical Society, 2013-11-21)Tunable, high-performance, two-photon absorption (TPA)-based amplified spontaneous emission (ASE) from near-unity quantum efficiency colloidal quantum dots (CQDs) is reported. Besides the absolute spectral tuning of ASE, ... -
CdSe/CdSe1-xTex core/crown heteronanoplatelets: tuning the excitonic properties without changing the thickness
Kelestemur Y.; Guzelturk, B.; Erdem, O.; Olutas M.; Erdem, T.; Usanmaz, C. F.; Gungor K.; Demir, Hilmi Volkan (American Chemical Society, 2017)Here we designed and synthesized CdSe/CdSe1-xTex core/crown nanoplatelets (NPLs) with controlled crown compositions by using the core-seeded-growth approach. We confirmed the uniform growth of the crown regions with ... -
Colloidal nanoplatelet/conducting polymer hybrids: excitonic and material properties
Guzelturk, B.; Menk, F.; Philipps, K.; Kelestemur Y.; Olutas M.; Zentel, R.; Demir, Hilmi Volkan (American Chemical Society, 2016)Here we present the first account of conductive polymer/colloidal nanoplatelet hybrids. For this, we developed DEH-PPV-based polymers with two different anchor groups (sulfide and amine) acting as surfactants for CdSe ... -
Colloidal quantum dot light-emitting diodes employing phosphorescent small organic molecules as efficient exciton harvesters
Mutlugun, E.; Guzelturk, B.; Abiyasa, A. P.; Gao, Y.; Sun X. W.; Demir, Hilmi Volkan (American Chemical Society, 2014)Nonradiative energy transfer (NRET) is an alternative excitation mechanism in colloidal quantum dot (QD) based electroluminescent devices (QLEDs). Here, we develop hybrid highly spectrally pure QLEDs that facilitate energy ... -
Cucurbit [7] uril-threaded fluorene-thiophene-based conjugated polyrotaxanes
Idris, M.; Bazzar, M.; Guzelturk, B.; Demir, Hilmi Volkan; Tuncel, D. (Royal Society of Chemistry, 2016)Here we investigate the effect of cucurbit[7]uril (CB7) on the thermal and optical properties of fluorene-thiophene based conjugated polyelectrolytes. For this purpose, poly(9,9′-bis(6′′-(N,N,N-trimethylammonium)hexyl)fl ... -
Efficient nonradiative energy transfer from InGaN/GaN nanopillars to CdSe/ZnS core/shell nanocrystals
Nizamoglu, S.; Guzelturk, B.; Jeon, D. W.; Lee, I. H.; Demir, Hilmi Volkan (AIP Publishing, 2011-04-20)In this study, we propose and demonstrate efficient electron-hole pair injection from InGaN/GaN multiple quantum well nanopillars (MQW-NPs) to CdSe/ZnS core/shell nanocrystal quantum dots (NQDs) via Forster-type nonradiative ... -
Evidence for Nonradiative Energy Transfer in Graphene-Oxide-Based Hybrid Structures
Yeltik, A.; Kucukayan-Dogu, G.; Guzelturk, B.; Fardindoost, S.; Kelestemur, Y.; Demir, Hilmi Volkan (American Chemical Society, 2013-11-13)Solution processed graphene variants including graphene oxide (GO) and reduced graphene oxide (RGO) are promising materials for potential optoelectronic applications. To date, efficiency of the excitation energy transfer ... -
Exciton dynamics of colloidal semiconductor quantum well stacks
Erdem, O.; Guzelturk, B.; Olutas M.; Kelestemur Y.; Demir, Hilmi Volkan (Springer Netherlands, 2018)Colloidal semiconductor nanoplatelets (NPLs) have recently emerged as a new class of colloidal nanocrystals. NPLs are quasi two-dimensional nanocrystals having atomically flat surfaces and have unique properties such as ... -
Excitonic enhancement of nonradiative energy transfer to bulk silicon with the hybridization of cascaded quantum dots
Yeltik A.; Guzelturk, B.; Hernandez-Martinez, P. L.; Akhavan S.; Demir, Hilmi Volkan (AIP, 2013)We report enhanced sensitization of silicon through nonradiative energy transfer (NRET) of the excitons in an energy-gradient structure composed of a cascaded bilayer of green- and red-emitting CdTe quantum dots (QDs) on ... -
Excitonics of semiconductor quantum dots and wires for lighting and displays
Guzelturk, B.; Martinez, P. L. H.; Zhang, Q.; Xiong, Q.; Sun, H.; Sun, X. W.; Govorov, A. O.; Demir, Hilmi Volkan (Wiley-VCH Verlag, 2013)In the past two decades, semiconductor quantum dots and wires have developed into new, promising classes of materials for next-generation lighting and display systems due to their superior optical properties. In particular, ... -
High-efficiency optical gain in type-II semiconductor nanocrystals of alloyed colloidal quantum wells
Guzelturk, B.; Kelestemur Y.; Olutas M.; Li, Q.; Lian, T.; Demir, Hilmi Volkan (American Chemical Society, 2017)Colloidal nanocrystals having controlled size, tailored shape, and tuned composition have been explored for optical gain and lasing. Among these, nanocrystals having Type-II electronic structure have been introduced toward ... -
Highly efficient nonradiative energy transfer from colloidal semiconductor quantum dots to wells for sensitive noncontact temperature probing
Olutas M.; Guzelturk, B.; Kelestemur Y.; Gungor K.; Demir, Hilmi Volkan (Wiley-VCH Verlag, 2016)This study develops and shows highly efficient exciton-transferring hybrid semiconductor nanocrystal films of mixed dimensionality comprising quasi 0D and 2D colloids. Through a systematic study of time-resolved and ... -
Highly polarized light emission by isotropic quantum dots integrated with magnetically aligned segmented nanowires
Uran, C.; Erdem, T.; Guzelturk, B.; Perkgöz, N. K.; Jun, S.; Jang, E.; Demir, Hilmi Volkan (American Institute of Physics, 2014)In this work, we demonstrate a proof-of-concept system for generating highly polarized light from colloidal quantum dots (QDs) coupled with magnetically aligned segmented Au/Ni/Au nanowires (NWs). Optical characterizations ... -
Large-area semi-transparent light-sensitive nanocrystal skins
Akhavan, S.; Guzelturk, B.; Sharma, V. K.; Demir, Hilmi Volkan (Optical Society of America, 2012)We report a large-area, semi-transparent, light-sensitive nanocrystal skin (LS-NS) platform consisting of single monolayer colloidal nanocrystals. LS-NS devices, which were fabricated over areas up to 48 cm(2) using ... -
Near-field energy transfer using nanoemitters for optoelectronics
Guzelturk, B.; Demir, Hilmi Volkan (Wiley-VCH Verlag, 2016)Effective utilization of excitation energy in nanoemitters requires control of exciton flow at the nanoscale. This can be readily achieved by exploiting near-field nonradiative energy transfer mechanisms such as dipole-dipole ... -
Near-unity emitting copper-doped colloidal semiconductor quantum wells for luminescent solar concentrators
Sharma, M.; Gungor K.; Yeltik A.; Olutas M.; Guzelturk, B.; Kelestemur Y.; Erdem, T.; Delikanli S.; McBride, J. R.; Demir, Hilmi Volkan (Wiley-VCH Verlag, 2017)Doping of bulk semiconductors has revealed widespread success in optoelectronic applications. In the past few decades, substantial effort has been engaged for doping at the nanoscale. Recently, doped colloidal quantum dots ... -
Phonon-assisted exciton transfer into silicon using nanoemitters: the role of phonons and temperature effects in förster resonance energy transfer
Yeltik A.; Guzelturk, B.; Hernandez-Martinez, P. L.; Govorov, A. O.; Demir, Hilmi Volkan (American Chemical Society, 2013)We study phonon-assisted Forster resonance energy transfer (FRET) into an indirect band-gap semiconductor using nanoemitters. The unusual temperature dependence of this energy transfer, which is measured using the donor ... -
Platelet-in-Box Colloidal Quantum Wells: CdSe/CdS@CdS Core / Crown@Shell Heteronanoplatelets
Kelestemur Y.; Guzelturk, B.; Erdem, O.; Olutas M.; Gungor K.; Demir, Hilmi Volkan (Wiley-VCH Verlag, 2016)Here, the CdSe/CdS@CdS core/crown@shell heterostructured nanoplatelets (NPLs) resembling a platelet-in-box structure are developed and successfully synthesized. It is found that the core/crown@shell NPLs exhibit consistently ... -
Singlet and Triplet Exciton Harvesting in the Thin Films of Colloidal Quantum Dots Interfacing Phosphorescent Small Organic Molecules
Guzelturk, B.; Hernandez Martinez P.L.; Zhao, D.; Sun X.W.; Demir, Hilmi Volkan (American Chemical Society, 2014)Efficient nonradiative energy transfer is reported in an inorganic/organic thin film that consists of a CdSe/ZnS core/shell colloidal quantum dot (QD) layer interfaced with a phosphorescent small organic molecule (FIrpic) ...