Article
Chemistry, Multidisciplinary
Sander J. W. Vonk, Bart A. J. Heemskerk, Robert C. Keitel, Stijn O. M. Hinterding, Jaco J. Geuchies, Arjan J. Houtepen, Freddy T. Rabouw
Summary: A novel spectroscopic method, cascade spectroscopy, was used to quantify the biexciton line width and binding energy of single CdSe/CdS/ZnS colloidal quantum dots at room temperature. The average emission line width of biexcitons was found to be 86 meV, similar to that of excitons, with variations in biexciton repulsion more narrowly distributed than variations in exciton energy. Inhomogeneous broadening in the sample was primarily attributed to variations in the CdS shell thickness.
Article
Chemistry, Physical
Go Yumoto, Yoshihiko Kanemitsu
Summary: Lead halide perovskite nanocrystals have gained considerable attention as next-generation optoelectronic materials. This article summarizes recent advances in the photophysics of excitons and biexcitons in these nanocrystals. Understanding their dynamics is crucial for optimal design of optoelectronic devices and the development of new functional properties.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Haochen Sun, Paul Cavanaugh, Ilan Jen-La Plante, Christian Ippen, Maria Bautista, Ruiqing Ma, David F. Kelley
Summary: Transient absorption and time-resolved photoluminescence spectroscopies were used to study the hole tunneling and Auger dynamics in high-quality InP/ZnSe/ZnS quantum dots. The study revealed that trapped holes can tunnel into the valence band, converting one type of biexciton to another type.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Athanasios Smponias, Dionisis Stefanatos, Emmanuel Paspalakis
Summary: In this study, a hybrid nanostructure composed of a semiconductor quantum dot coupled to a metallic nanoparticle was investigated for the efficient creation of biexciton state using linearly polarized laser pulses. Numerical simulations showed that a simple on-off-on pulse-sequence can efficiently prepare the biexciton state even in the presence of the nanoparticle, for various interparticle distances and biexciton energy shifts. The pulse durations in the sequence were determined by solving a transcendental equation.
Article
Chemistry, Multidisciplinary
Xueyang Li, Jun Du, Guohui Zhao, Boyu Zhang, Clement Livache, Namyoung Ahn, Yuxi Jia, Mingrun Li, Ying Chen, Jingyi Zhu, Jingwei Guo, Victor I. Klimov, Kaifeng Wu
Summary: A new type of liquid optical-gain medium using compact compositionally-graded quantum dots has been demonstrated, showing broad-band optical gain and stable operation under intense photoexcitation. Two-color amplified spontaneous emission has been achieved using nanosecond pulses.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Ying Tang, Qilin Qin, Hongyu Yang, Shengnan Feng, Chunfeng Zhang, Jiayu Zhang, Min Xiao, Xiaoyong Wang
Summary: This study demonstrates the ability to decrease the Auger decay and radiative rates in semiconductor nanocrystals by applying external electric fields. The decrease in the Auger rate is attributed to enhanced exciton-exciton repulsion, while the decrease in the radiative rate is attributed to weakened electron-hole exchange interaction. These findings highlight the potential of using external electric fields as a post-synthetic approach to manipulate the exciton recombination dynamics in semiconductor nanocrystals.
Review
Chemistry, Multidisciplinary
Ivan Marri, Stefano Ossicini
Summary: The development of novel nanostructured solar cell devices using low-dimensional materials has shown potential in improving energy conversion efficiency. Utilizing quantum confinement effects in nanocrystals and carrier multiplication technology are key strategies for enhancing the performance of photovoltaic systems.
Article
Materials Science, Multidisciplinary
Taofang Zeng, Yi He
Summary: The study establishes a computationally executable approach for modeling electron-phonon and exciton-phonon interaction in semiconductor nanoclusters. It reveals the significance of single-phonon and multiple-phonon nonradiative relaxation for electrons and excitons in nanocrystals. Nonradiative relaxation rates in Si(46) are consistent with experimental results reported for similar nanocrystals.
Article
Nanoscience & Nanotechnology
Jie Meng, Qian Zhao, Weihua Lin, Tonu Pullerits, Kaibo Zheng
Summary: This study demonstrates the biexciton dynamics of core/shell quantum dots with submonolayer shell coverage. The results show that these quantum dots have a prolonged Auger lifetime. However, unlike conventional quantum dots, the dependence of the Auger recombination time on quantum dot size features two constant stages. This study provides a reference for the application of core-shell quantum dots in optoelectronic devices.
ADVANCED ELECTRONIC MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Athanasios Smponias, Dionisis Stefanatos, George P. Katsoulis, Ioannis Thanopulos, Emmanuel Paspalakis
Summary: This study investigates the effect of a spherical metallic nanoparticle on the population transfer from the ground to the biexciton state of a semiconductor quantum dot using linearly chirped Gaussian pulses. The presence of the nanoparticle improves the biexciton state preparation, particularly for large biexciton energy shifts and small interparticle distances. These findings suggest potential applications in nanoscale photonic devices and future quantum technologies.
Article
Materials Science, Multidisciplinary
Lintao Peng, Wooje Cho, Xufeng Zhang, Dmitri Talapin, Xuedan Ma
Summary: Bright biexciton emission at high excitation powers was observed in CdSe/CdS core/shell NPLs, with an average binding energy of 16.5 meV, indicating charging-decharging dynamics of the NPLs mediated by the Auger ionization process. These findings are important for efficient biexciton emission in energy, lighting, and quantum applications.
PHYSICAL REVIEW MATERIALS
(2021)
Article
Chemistry, Physical
Sander J. W. Vonk, Freddy T. Rabouw
Summary: Experiments have shown temporal fluctuations in the emission efficiency of single colloidal quantum dots (QDs), known as blinking, which are caused by the opening/closing of charge-carrier traps and/or charging/discharging of the QD. In this study, the fluctuations of biexciton efficiency in single CdSe/CdS/ZnS core-shell QDs were quantified. It was found that the biexciton efficiency blinked significantly. The charging of a QD accelerates Auger recombination, while opening/closing of a charge-carrier trap increases the nonradiative recombination rate. A revised model based on reversible trapping was proposed to explain the fast rate of trap-assisted recombination. The implications of biexciton blinking for lasing applications were also discussed.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Chemistry, Physical
Ashish Soni, Dushyant Kushavah, Li-Syuan Lu, Wen-Hao Chang, Suman Kalyan Pal
Summary: Utilizing the excess energy from photoexcitation to improve the efficiency of next-generation light-harvesting devices is possible. Multiple exciton generation (MEG) in semiconducting materials can break the conversion efficiency limit of photovoltaic devices. Monolayer transition metal dichalcogenides (TMDs) have high absorption coefficients and show efficient MEGs with low threshold energy and high (86%) efficiency in MoS2. The results suggest that van der Waals layered materials could be a potential candidate for flexible and efficient next-generation solar cells and photodetectors.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Alexandra Brumberg, Nicolas E. Watkins, Benjamin T. Diroll, Richard D. Schaller
Summary: Colloidal semiconductor nanocrystals, such as CdSe nanoplatelets and quantum dots, offer advantages in optoelectronics but are affected by rapid nonradiative Auger recombination at high excitation intensities. This study investigates the temperature dependence of excited state lifetime and fluence-dependent emission, revealing fundamental differences between CdSe nanoplatelets and core-only quantum dots, and highlighting the increased utility of photogenerated excitons and multiexcitons at low temperatures.
Article
Chemistry, Physical
Shawn Irgen-Gioro, Yue Wu, Rafael Lopez-Arteaga, Suyog Padgaonkar, Jack N. Olding, Emily A. Weiss
Summary: This study investigates the emission characteristics of CdSe/CdS core/shell nanplatelets and finds that blinking primarily occurs on time scales from 100 ps to seconds, while spectral diffusion mainly occurs on time scales of approximately 1 second and slower. Shorter time scale blinking is attributed to an equilibrium between dark and bright states, while longer time scale blinking involves an equilibrium between two distinct emissive states.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Chemistry, Multidisciplinary
Hoang Long Nguyen, Thanh Nhut Do, Emek G. Durmusoglu, Merve Izmir, Ritabrata Sarkar, Sougata Pal, Oleg V. Prezhdo, Hilmi Volkan Demir, Howe-Siang Tan
Summary: In this study, the ultrafast spectral diffusion, vibronic dynamics, and energy relaxation of CdSe colloidal quantum wells (CQWs) at room temperature were measured using two-dimensional electronic spectroscopy (2DES). The energy relaxation from light-hole (LH) excitons to heavy-hole (HH) excitons was observed to occur within a time scale of approximately 210 fs. Equilibration dynamics between the spectroscopically accessible HH excitonic state and a dark state were found to take place within a time scale of approximately 160 fs. The spectral diffusion dynamics in HH excitons were analyzed using center line slope analysis, revealing a sub-200 fs decay and oscillatory features resolved at 4 and 25 meV. Quantum calculations were performed to replicate and explain the observed dynamics. The 4 meV mode was found to be in the near-critically damped regime and may mediate the transition between the bright and dark HH excitons. These findings demonstrate the capability of 2DES to comprehensively and detailedly characterize the ultrafast spectral properties in CQWs and similar nanomaterials.
Article
Chemistry, Multidisciplinary
Farzan Shabani, Pedro Ludwig Hernandez Martinez, Nina Shermet, Hilal Korkut, Ibrahim Sarpkaya, Hamed Dehghanpour Baruj, Savas Delikanli, Furkan Isik, Emek Goksu Durmusoglu, Hilmi Volkan Demir
Summary: This work presents the synthesis and optical characterization of CdSe/CdSeTe/CdTe core/crown/crown nanoplatelets (NPLs) with a stepwise gradient electronic structure. The excitonic properties of the NPLs can be finely tuned through adjusting the geometry of the intermediate crown. These NPLs exhibit long-lifetime red-shifted emission spectra and high two-photon absorption cross-sections, making them promising for designing complex heterostructures with remarkable properties.
Article
Materials Science, Multidisciplinary
Dmitry A. Tatarinov, Sergey S. Anoshkin, Ivan A. Tsibizov, Volodymyr Sheremet, Furkan Isik, Alexey Y. Zhizhchenko, Artem B. Cherepakhin, Aleksandr A. Kuchmizhak, Anatoly P. Pushkarev, Hilmi Volkan Demir, Sergey V. Makarov
Summary: A protocol to deposit large-grain and smooth CsPbBr3 thin films is developed, achieving high optical gain and excellent lasing characteristics. The critical roles of thickness and grain size for CsPbBr3 films with extremely high optical gain are revealed, opening up possibilities for low-threshold lasers and integrated photonic chips.
ADVANCED OPTICAL MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Emek G. Durmusoglu, Sujuan Hu, Pedro Ludwig Hernandez-Martinez, Merve Izmir, Farzan Shabani, Min Guo, Huayu Gao, Furkan Isik, Savas Delikanli, Vijay Kumar Sharma, Baiquan Liu, Hilmi Volkan Demir
Summary: This article presents the development of CdSe/CdTe/CdSe core/crown/crown (multi-crowned) type-II colloidal quantum wells (CQWs) and investigates their optical properties. The multi-crowned CQWs show a high quantum yield of 83% and a long fluorescence lifetime of 73.3 ns, surpassing traditional core/crown heterostructures. Proof-of-concept NPL-LEDs based on these multi-crowned CQWs achieved a record high external quantum efficiency of 7.83%.
Article
Chemistry, Multidisciplinary
Roman A. Babunts, Yulia A. Uspenskaya, Nikolai G. Romanov, Sergei B. Orlinskii, Georgy V. Mamin, Elena V. Shornikova, Dmitri R. Yakovlev, Manfred Bayer, Furkan Isik, Sushant Shendre, Savas Delikanli, Hilmi Volkan Demir, Pavel G. Baranov
Summary: Semiconductor colloidal nanoplatelets based on CdSe with magnetic Mn2+ ions show modified magneto-optical and spin-dependent properties. High-frequency electron paramagnetic resonance techniques were used to study the spin structure and dynamics of Mn2+ ions in core/shell CdSe/(Cd,Mn)S nanoplatelets. Two sets of resonances were observed, indicating different spin dynamics between surface and inner Mn2+ ions. The interaction between surface Mn2+ ions and 1H nuclei was measured using electron nuclear double resonance, providing information on the distances between Mn2+ ions and 1H nuclei.
Article
Chemistry, Multidisciplinary
M. A. Masharin, A. K. Samusev, A. A. Bogdanov, I. V. Iorsh, H. V. Demir, S. V. Makarov
Summary: Excitons in lead bromide perovskites have a high binding energy and high oscillator strength, which enables strong light-matter coupling in perovskite-based cavities at the nanoscale. In this study, a perovskite metasurface fabricated with nanoimprint lithography is used to demonstrate room-temperature polariton lasing. The observed lasing emission has a high directivity and compatibility with various planar photonic platforms.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Chemistry, Physical
Farzan Shabani, Muhammad Ahmad, Satish Kumar, Savas Delikanli, Furkan Isik, Arinjoy Bhattacharya, Athos Petrou, Hilmi Volkan Demir
Summary: Two-dimensional (2D) core/shell nanoplatelets (NPLs) synthesized via the hot-injection method provide excellent thermal and chemical stability for high-temperature doping. A thermodynamic approach toward silver doping of these NPLs is proposed and demonstrated. The distribution of silver ions in the lattice of the NPLs directly affects the recombination dynamics and enables fine-tuning of the near-infrared emission.
CHEMISTRY OF MATERIALS
(2023)
Article
Chemistry, Physical
Merve Izmir, Emek G. Durmusoglu, Manoj Sharma, Farzan Shabani, Furkan Isik, Savas Delikanli, Vijay Kumar Sharma, Hilmi Volkan Demir
Summary: In this study, ytterbium (Yb) was successfully doped into cadmium selenide (CdSe) nanoplatelets (NPLs) using a modified seeded-growth method. The Yb-doped NPLs exhibited additional near-infrared (NIR) emission apart from their excitonic emission. By optimizing the dopant concentration, an impressive photoluminescence quantum yield (PL QY) of approximately 55% was achieved. Detailed elemental and optical characterizations were performed to understand the emerging photophysical properties of these Yb-doped NPLs. These lanthanide-doped CdSe NPLs emitting in the NIR range could find applications in next-generation bioimaging, night vision, and photodetection.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Nanoscience & Nanotechnology
Pavel A. Dmitriev, Emmanuel Lassalle, Lu Ding, Zhenying Pan, Darren C. J. Neo, Vytautas Valuckas, Ramon Paniagua-Dominguez, Joel K. W. Yang, Hilmi Volkan Demir, Arseniy I. Kuznetsov
Summary: In this study, we propose and demonstrate single subwavelength hybrid dielectric-plasmonic optical nanoantennas that are coupled to localized quantum dot emitters and serve as efficient and bright unidirectional photon sources. The structure supports both antenna mode and gap mode resonances, and the resonance spectral positions can be controlled by tuning geometrical parameters. Experimental results show fluorescence enhancement factors up to 654x folds, mainly due to high radiative efficiencies, and directional emission of the photoluminescence into a cone of +/- 17 degrees normal to the sample plane. We believe this solution is viable and relevant for the next generation of light-emitting devices.
Article
Chemistry, Multidisciplinary
Xiao Liang, Emek G. Durmusoglu, Maria Lunina, Pedro Ludwig Hernandez-Martinez, Vytautas Valuckas, Fei Yan, Yulia Lekina, Vijay Kumar Sharma, Tingting Yin, Son Tung Ha, Ze Xiang Shen, Handong Sun, Arseniy Kuznetsov, Hilmi Volkan Demir
Summary: This study demonstrates the control of electrostatic interactions in semiconductor nanocrystals through a doubly gradient core-shell architecture, paving the way for the development of high-performance optoelectronic devices.
Review
Chemistry, Physical
Joanna Dehnel, Adi Harchol, Yahel Barak, Itay Meir, Faris Horani, Arthur Shapiro, Rotem Strassberg, Celso de Mello Donega, Hilmi Volkan Demir, Daniel R. Gamelin, Kusha Sharma, Efrat Lifshitz
Summary: Incorporating magnetic ions into semiconductor nanocrystals is a promising research field for manipulating spin-related properties. Various host materials and magnetic ions have been studied, and the impact of nanostructure engineering and ion selection in carrier-magnetic ion interactions is emphasized. The use of optically detected magnetic resonance spectroscopy provides valuable insights into the spin dynamics and physical parameters of the carrier-magnetic ion interactions.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Optics
Tevfik bulent Kanmaz, Efe Ozturk, Hilmi volkan Demir, Cigdem Gunduz-demir
Summary: This paper proposes and demonstrates a deep-learning-enabled method for rapid prediction of electromagnetic near-field response and inverse prediction of metasurface designs. By using an encoder-decoder neural network, the common limitation of predicting only transmission spectra is overcome.
Article
Chemistry, Multidisciplinary
Kubra Onbasli, Gozde Demirci, Furkan Isik, Emek Goksu Durmusoglu, Hilmi Volkan Demir, Havva Yagci Acar
Summary: Fluorescent, CdSe/CdS core/crown heterostructured nanoplatelets (NPLs) were transferred to water through a single-step ligand exchange using 2-mercaptopropionic acid. These stable, aqueous NPLs were loaded with a drug, 5-aminolevulinic acid (ALA), and were used for enhanced photodynamic therapy of both androgen-dependent and -independent human prostate cancer cells.
CHEMICAL COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Zeynep Dikmen, Ahmet Tarik Isik, Iklim Bozkaya, Hamed Dehghanpour Baruj, Betul Canimkurbey, Farzan Shabani, Muhammad Ahmad, Hilmi Volkan Demir
Summary: We propose and demonstrate the vertical self-assembly of colloidal quantum wells (CQWs) for amplified spontaneous emission (ASE) and random lasing. The CQWs are stacked in films using liquid-air interface self-assembly (LAISA) and controlled hydrophilicity/lipophilicity balance (HLB). By adjusting HLB with a more lyophilic subphase, large micron-sized areas of monolayer CQW stacks can be obtained. ASE and random lasing are achieved by depositing multi-layered CQW stacks onto a substrate using the Langmuir-Schaefer transfer method.
Article
Chemistry, Multidisciplinary
Taylan Bozkaya, Furkan Isik, Iklim Bozkaya, Savas Delikanli, Emre Unal, Hilmi Volkan Demir
Summary: A new class of light-sensitive nanocrystal skins (LS-NS) utilizing a monolayer of face-down orientation-controlled self-assembled CQWs as the active absorbing layer in the UV-visible range is developed, enabling non-conventional photosensing operation and self-powered operation.