Article
Chemistry, Physical
Lifeng Wang, Dongmei Xiang, Kaimin Gao, Junhui Wang, Kaifeng Wu
Summary: Colloidal n-doped CdSe and CdSe/ZnS nanoplatelets have been achieved through a photochemical doping method, demonstrating successful additional electron doping at the conduction band edge. The key to successful doping lies in a high surface ligand coverage, while unpassivated surface cations may lead to depletion of the doped electrons.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Chemistry, Physical
Arman Najafi, Manoj Sharma, Savas Delikanli, Arinjoy Bhattacharya, Joseph R. Murphy, James Pientka, Ashma Sharma, Alexander P. Quinn, Onur Erdem, Subash Kattel, Yusuf Kelestemur, Maksym Kovalenko, William D. Rice, Hilmi Volkan Demir, Athos Petrou
Summary: This study investigates light-induced magnetism in Ag+-doped CdSe nanoplatelets using magnetic circularly polarized luminescence and magnetic circular dichroism spectroscopy, confirming the presence of paramagnetism. The observed magnetism is attributed to the transformation of nonmagnetic Ag+ ions into Ag2+ with a nonzero magnetic moment, suggesting potential applications in spintronic devices.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Chemistry, Physical
Dongmei Xiang, Yulu Li, Lifeng Wang, Tao Ding, Junhui Wang, Kaifeng Wu
Summary: In this study, the electron and hole spin dynamics in CdSe colloidal nanoplatelets of varying thicknesses were investigated using circularly polarized transient absorption spectroscopy. The results showed that hole spin-flip occurred within 200 fs, while the electron spin lifetime decreased as the platelet thickness was reduced. The findings suggest an exchange interaction between the electron and the hole, and/or surface dangling bond spins enhanced by quantum confinement.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Chemistry, Multidisciplinary
Albert F. Vong, Shawn Irgen-Gioro, Yue Wu, Emily A. Weiss
Summary: Colloidal semiconductor nanoplatelets are scalable materials for optoelectronic applications and can be used for spin-to-photon transduction in quantum information networks. Negative trions are appealing emitters, but more preparation knowledge is needed to use them as single photon-emitting states. Through power-dependent time-resolved transient absorptions, it was shown that trions form via biexciton decay and not through collisional mechanisms typical for 2D materials.
Article
Chemistry, Physical
Da-Eun Yoon, Juho Lee, Hyeonwoo Yeo, Junga Ryou, Young Kuk Lee, Yong-Hoon Kim, Doh C. Lee
Summary: Shape anisotropy in colloidal zincblende CdSe nanoplatelets directly affects their optical and electronic properties. The lateral aspect ratio of NPLs provides a way to control their optical characteristics, such as polarized emission, by varying the shape while keeping the thickness constant. Experimental and simulation studies have shown that the growth behavior of CdSe NPLs can be altered by adjusting the Cd(ac)(2)-to-Se precursor ratio, leading to different growth directions. The mechanism for the lateral growth of zincblende NPLs has been explained at the atomic level, shedding light on the transition processes of NPL morphology and growth direction.
CHEMISTRY OF MATERIALS
(2021)
Article
Chemistry, Multidisciplinary
Sergey R. Meliakov, Vasilii V. Belykh, Ina V. Kalitukha, Aleksandr A. Golovatenko, Alessio Di Giacomo, Iwan Moreels, Anna V. Rodina, Dmitri R. Yakovlev
Summary: The coherent spin dynamics of electrons in CdSe colloidal nanoplatelets were investigated at different temperatures. The measurements revealed the g-factors of the nanoplatelets and the electron spin precession in a magnetic field. The results showed weak dependence of the spin dephasing time on temperature and the longitudinal spin relaxation time exceeding 10 ns even at room temperature. The observations also confirmed the negative charge of the nanoplatelets and revealed g-factor anisotropy.
Article
Chemistry, Multidisciplinary
Carmelita Roda, Pieter Geiregat, Alessio Di Giacomo, Iwan Moreels, Zeger Hens
Summary: In this study, we used cross-polarized pump-probe spectroscopy to measure the absorption coefficient spectrum of the exciton-biexciton transition in colloidal CdSe nanoplatelets (NPLs) and determined the biexciton oscillator strength (fBX). We found that fBX is independent of the NPL area and agrees with predictions of a short-range interaction model.
Article
Materials Science, Multidisciplinary
Alexander M. Smirnov, Anastasia D. Golinskaya, Vladimir N. Mantsevich, Maria Kozlova, Kseniia V. Ezhova, Bedil M. Saidzhonov, Roman B. Vasiliev, Vladimir S. Dneprovskii
Summary: Experimental investigations were conducted on the transient absorption of colloidal heterostructured CdSe/CdS nanoplatelets under high-intensity nanosecond laser pulses, revealing a strong dependence on nanoplatelets concentration and pump intensities. Nonlinear transmission changes in nanoplatelets solutions were explained by various factors, and the identification of conditions for optical gain in colloidal solutions was a significant result.
RESULTS IN PHYSICS
(2022)
Article
Chemistry, Physical
Tom Galle, Daniel Spittel, Nelli Weiss, Volodymyr Shamraienko, Helena Decker, Maximilian Georgi, Rene Huebner, Nadia Metzkow, Christine Steinbach, Dana Schwarz, Vladimir Lesnyak, Alexander Eychmueller
Summary: The research transforms CdSe NPLs into PbSe NPLs suitable for optoelectronic applications through cation exchange, ligand exchange, and electronic coupling, successfully fabricating a photodetector with fast light response at low operational voltages on a commercial substrate.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Chemistry, Multidisciplinary
Alexandra Brumberg, Matthew S. Kirschner, Benjamin T. Diroll, Kali R. Williams, Nathan C. Flanders, Samantha M. Harvey, Ariel A. Leonard, Nicolas E. Watkins, Cunming Liu, Eli D. Kinigstein, Jin Yu, Austin M. Evans, Yuzi Liu, Shelby A. Cuthriell, Shobhana Panuganti, William R. Dichtel, Mercouri G. Kanatzidis, Michael R. Wasielewski, Xiaoyi Zhang, Lin X. Chen, Richard D. Schaller
Summary: Time-resolved X-ray diffraction study reveals that photoexcitation induces greater out-of-plane disordering in 4 and 5 monolayer NPLs, while 3 ML NPLs display the opposite behavior. In comparison, disordering in zero-dimensional CdSe nanocrystals is isotropic and recovery is faster. These findings support the superior performance of NPLs in optoelectronic applications.
Article
Nanoscience & Nanotechnology
Dongmei Xiang, Yulu Li, Lifeng Wang, Yang Zhao, Kaifeng Wu
Summary: Recent studies have demonstrated strong optical Stark effect (OSE) in emerging semiconductor materials, and proposed the concept of double-OSE, deepening our understanding of light-matter interaction in colloidal nanoplatelets and providing potential applications for optical modulation or information processing technologies.
Article
Nanoscience & Nanotechnology
Avisek Dutta, Amani Saleh Almutairi, Jojo P. Joseph, Alexander Baev, Athos Petrou, Hao Zeng, Paras N. Prasad
Summary: Transition-metal-doped semiconductor nanocrystals, particularly two-dimensional materials, have attracted significant attention due to their useful optical and magnetic properties. In this study, we investigate the magnetic and magneto-optic properties of copper-doped CdSe nanoplatelets synthesized using a high-temperature colloidal technique. Our results show that doped nanoplatelets exhibit more prominent excitonic features compared to undoped nanoplatelets at cryogenic temperatures. Furthermore, the study provides a detailed analysis of the magneto-optical behavior of doped nanoplatelets in the presence of paramagnetic copper ions.
Article
Optics
I. D. Laktaev, B. M. Saidzhonov, R. B. Vasiliev, A. M. Smirnov, O. V. Butov
Summary: The photoluminescence features of a light-hole - electron exciton transition in CdSe/CdS nanoplatelets colloidal solution under resonant two-photon excitation were investigated. The powerlaw dependence of the photoluminescence intensity on the excitation laser femtosecond pulses intensity was discovered to be related to biexciton radiation. In addition, the conditions for the photoluminescence growth and quenching were determined based on the concentration and pump intensity.
JOURNAL OF LUMINESCENCE
(2022)
Article
Chemistry, Multidisciplinary
Olga O. Smirnova, Ina V. Kalitukha, Anna V. Rodina, Grigorii S. Dimitriev, Victor F. Sapega, Olga S. Ken, Vladimir L. Korenev, Nikolai V. Kozyrev, Sergey V. Nekrasov, Yuri G. Kusrayev, Dmitri R. Yakovlev, Benoit Dubertret, Manfred Bayer
Summary: This study investigates the optical alignment and orientation of excitons in colloidal nanoplatelets and evaluates their properties through theoretical analysis and experimental data.
Article
Chemistry, Multidisciplinary
Hongyu Yang, Lei Zhang, Wenbin Xiang, Changgui Lu, Yiping Cui, Jiayu Zhang
Summary: In this study, room-temperature exciton-polariton Bose-Einstein condensation was achieved and the realization of polariton laser was confirmed. Colloidal nanoplatelets show great prospects in low-cost, high-performance polariton devices and coherent light sources.
Article
Polymer Science
Minju Oh, Whi Dong Kim, Mao Zhang, Taehyeong Kim, Dayoung Yoo, Soo Hyung Kim, Dongyun Lee
Summary: ABS polymer nanocomposite thin films with CBNs were fabricated and tested for mechanical properties. Results showed that fullerene composite exhibited higher tensile strength, while elastic modulus and hardness decreased with increasing CBNs content in nanoindentation tests.
Article
Chemistry, Physical
Da-Eun Yoon, Juho Lee, Hyeonwoo Yeo, Junga Ryou, Young Kuk Lee, Yong-Hoon Kim, Doh C. Lee
Summary: Shape anisotropy in colloidal zincblende CdSe nanoplatelets directly affects their optical and electronic properties. The lateral aspect ratio of NPLs provides a way to control their optical characteristics, such as polarized emission, by varying the shape while keeping the thickness constant. Experimental and simulation studies have shown that the growth behavior of CdSe NPLs can be altered by adjusting the Cd(ac)(2)-to-Se precursor ratio, leading to different growth directions. The mechanism for the lateral growth of zincblende NPLs has been explained at the atomic level, shedding light on the transition processes of NPL morphology and growth direction.
CHEMISTRY OF MATERIALS
(2021)
Article
Chemistry, Multidisciplinary
Seunghyun Rhee, Dongju Jung, Dahin Kim, Doh C. Lee, Changhee Lee, Jeongkyun Roh
Summary: This study reports polarized electroluminescence emission in high-performance QR-LEDs achieved by employing the Langmuir-Blodgett (LB) technique, which successfully aligns QRs and produces polarized light emission. The advantageous features of the LB technique, such as nondestructiveness, precise thickness control, and the nonnecessity of an additional matrix material, enable the fabrication of QR-LEDs in the same procedure as the standard spin coating-based scheme. The devices fabricated via the LB technique exhibit excellent performance, with low turn-on voltage, high peak luminance, and peak external quantum efficiency, indicating new opportunities for QRs in display technologies.
Article
Chemistry, Multidisciplinary
Sungjun Koh, Yoojin Choi, Ilsong Lee, Gui-Min Kim, Jayeong Kim, Young-Shin Park, Sang Yup Lee, Doh C. Lee
Summary: This article reports a method of photoinduced nitrogen fixation using a hybrid system composed of quantum dots (QDs) and bacteria to synthesize ammonia more efficiently. Experimental results show that QDs can be taken up by the bacteria and the photoexcited electrons are directly transferred to the catalytic component of nitrogenase. However, excess QDs disrupt the bacterial membrane and deactivate the enzyme. Successful uptake of a minimal amount of QDs is crucial for efficient photosensitized ammonia production.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Multidisciplinary Sciences
Dahin Kim, Dennis Ndaya, Reuben Bosire, Francis K. Masese, Weixingyue Li, Sarah M. Thompson, Cherie R. Kagan, Christopher B. Murray, Rajeswari M. Kasi, Chinedum O. Osuji
Summary: Liquid crystals (LCs) are promising materials for the fabrication of reconfigurable arrays of 2D nanomaterials. However, achieving stable dispersions of nanomaterials in LCs is challenging. In this study, good dispersions of pristine CdSe nanoplatelets (NPLs) in LCs were achieved, and their alignment and associated photoluminescence could be controlled by a magnetic field. The dispersion stability was greatly enhanced using polymeric LCs, and the stability was higher in the smectic phases compared to the nematic phases. The aligned composites exhibited highly polarized emission that could be manipulated by field-realignment, which can have applications in programmable materials for photonics.
NATURE COMMUNICATIONS
(2022)
Article
Multidisciplinary Sciences
Yizhou Zhang, Dahin Kim, Ruiqi Dong, Xunda Feng, Chinedum O. Osuji
Summary: This study demonstrates a class of organic solvent-stable nanoporous membranes with tunable pore sizes and chemical structures, enabling customized selectivity and permeability.
Article
Chemistry, Multidisciplinary
Dahin Kim, Wenbi Shcherbakov-Wu, Seung Kyun Ha, Woo Seok Lee, William A. Tisdale
Summary: Anisotropic strain engineering is a powerful strategy for enhancing the optoelectronic performance of semiconductor nanocrystals. By controlling the spatial position of the core within a shell, different degrees of strain can be introduced, resulting in changes in absorption and emission characteristics. The ability to control the strain intensity through core position provides opportunities for fine-tuning the electronic properties of nanocrystals.
Article
Chemistry, Physical
Da-Eun Yoon, Sangmin Yeo, Hyeonjun Lee, Hyunjin Cho, Nianfang Wang, Gui-Min Kim, Wan Ki Bae, Young Kuk Lee, Young-Shin Park, Doh C. Lee
Summary: In this study, CdZnSe/ZnS core/shell NPLs with significantly enhanced spectral tunability over a broad spectral range were synthesized. By carrying out a Cd-to-Zn direct cation exchange reaction on CdSe/ZnS core/shell NPLs, the composition of the emitting core was changed while maintaining the original shape of NPLs. As the core alloying proceeds, NPLs maintain excellent color purity and exhibit linearly polarized emission.
CHEMISTRY OF MATERIALS
(2022)
Article
Chemistry, Physical
Sungjun Koh, Hyeonjun Lee, Ju Young Woo, Wan Ki Bae, Young-Shin Park, Doh C. Lee
Summary: This paper reports the linearly polarized light absorption and emission of a new type of Cd-free branched nanocrystals (BNCs). By controlling the size and composition of the seed nanocrystals, the linearly polarized light emission of Cd-free BNCs can be tuned. Small-angle X-ray scattering analysis reveals that the polarization originates mainly from the broken symmetry in shape. In addition, the authors demonstrate the uniaxial alignment of BNCs under an external electric field, indicating the formation of a permanent dipole moment in anisotropic BNCs.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Chemistry, Multidisciplinary
Nianfang Wang, Seokhyeon Cheong, Da-Eun Yoon, Pan Lu, Hyunjoo Lee, Young Kuk Lee, Young-Shin Park, Doh C. Lee
Summary: Advances in nanotechnology have enabled precise design of catalytic sites for CO2 photoreduction, but most nanostructured photocatalysts have low activity. To address this issue, researchers constructed CdS nanosheets terminated by S2- atomic layers as intrinsic photocatalysts. Experimental results show that these nanostructures exhibit excellent photocatalytic performance, efficiently converting CO2 into CO with high selectivity.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Letter
Chemistry, Physical
Jun Hyuk Chang, Dongju Jung, Hak June Lee, Doyoon Shin, Youngdu Kim, Donghyo Hahm, Xinbiao Wang, Doh C. Lee, Euyheon Hwang, Young-Shin Park, Wan Ki Bae
Summary: The excitonic states in ZnSe1-XTeX nanocrystals and their photophysical characteristics were investigated, and it was found that nearest-neighbor Te pairs in ZnSe1-XTeX alloys create localized hole states, explaining the broadening of emission line widths and delayed recombination dynamics.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Nanoscience & Nanotechnology
Sungmin Jung, Han Gyeol Jang, Jun Young Jo, Yoon Sang Kim, Doh C. Lee, Jaewoo Kim
Summary: Smart polymer materials with damage-detection and self-healing functionalities are developed by incorporating spiropyran (SP) beads into a Diels-Alder (DA) matrix. The dual functionality is highly dependent on the proportion of polyurethane (PU), with the best performance achieved at 40 wt% PU. A high healing efficiency of 96% is achieved via a dynamic DA reaction, and the dual-functionality remains repeatable after 10 cycles with a slight reduction in detection and healing efficiencies.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Chemistry, Physical
Hyejeong Jang, Dongju Jung, Wan Ki Bae, Young-Shin Park, Doh C. Lee
Summary: Semiconductor nanocrystals with an anisotropic morphology, known as dot-in-rod (DIR) structure, exhibit unique properties such as linear polarization. In this study, CdSe/CdS DIR nanocrystals were synthesized, and the position of the CdSe core particle within the nanorods was controlled by varying the ligand compositions during CdS growth. The degree of linear polarization varied depending on the core position, with higher polarization observed for center-core DIRs compared to tip-core DIRs. Time-resolved photoluminescence analysis revealed that center-core DIRs had stronger electron-hole interaction due to weak uniaxial strain caused by lattice dislocations at the interface.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Jaehwan Lee, Jaeyeong Ha, Hyungdoh Lee, Hyunjin Cho, Doh C. Lee, Dmitri V. Talapin, Himchan Cho
Summary: This study proposes an efficient method for high-resolution patterning of InP-based quantum dots (QDs) using a photoacid generator while preserving their optical properties. By replacing chloride ligands with long-chain amine/carboxylate pair ligands, the photoluminescence quantum yield (PLQY) of the patterned InP-based QD films was successfully recovered to about 67% of the original PLQY, demonstrating the potential of the proposed patterning method.
ACS ENERGY LETTERS
(2023)
Article
Materials Science, Biomaterials
Ilsong Lee, Jieun Moon, Hoomin Lee, Sungjun Koh, Gui-Min Kim, Laure Gauthe, Francesco Stellacci, Yun Suk Huh, Pilhan Kim, Doh C. Lee
Summary: This study uses indium phosphide (InP) quantum dots (QDs) for photodynamic therapy (PDT) to treat infections caused by multidrug-resistant (MDR) bacteria, demonstrating superior bactericidal efficiency compared to common antibiotics. InP QDs generate superoxide during PDT, enabling efficient and selective killing of MDR bacteria while remaining non-toxic to mammalian cells. In in vivo studies, InP QDs showed excellent therapeutic and prophylactic efficacy in treating MDR bacterial infections.
BIOMATERIALS SCIENCE
(2022)