Article
Chemistry, Multidisciplinary
I. K. M. Reaz Rahman, Shiekh Zia Uddin, Matthew Yeh, Naoki Higashitarumizu, Jongchan Kim, Quanwei Li, Hyeonjun Lee, Kyuho Lee, Hoyeon Kim, Cheolmin Park, Jaehoon Lim, Joel W. Ager III, Ali Javey
Summary: In this study, a metal-oxide-semiconductor capacitor based on CdSe/CdS quantum dot thin films was used to investigate the influence of background charge on the luminescence efficiency and lifetime. By applying a gate voltage, the concentration ratio of charged and neutral quasiparticles in the quantum dots can be controlled, leading to modulation of the photoluminescence intensity and effective lifetime. The findings have potential applications in voltage-controlled electrochromics.
Article
Chemistry, Multidisciplinary
Daria D. Blach, Victoria A. Lumsargis, Daniel E. Clark, Chern Chuang, Kang Wang, Letian Dou, Richard D. Schaller, Jianshu Cao, Christina W. Li, Libai Huang
Summary: This study investigates the coherence of excitons in perovskite quantum dot solids by measuring the temperature-dependent photoluminescence line width and lifetime. The results show that excitons can coherently spread over three quantum dots in a superlattice, leading to superradiant emission. However, scattering from optical phonons causes the loss of coherence at higher temperatures, resulting in exciton localization to a single quantum dot. Static disorder and defects limit exciton coherence at low temperatures.
Article
Chemistry, Multidisciplinary
Shiekh Zia Uddin, Eran Rabani, Ali Javey
Summary: Exciton-exciton annihilation (EEA) becomes the dominant loss mechanism at high densities in excitonic materials, and the EEA coefficient is inversely related to the single-exciton lifetime, resulting in a counterintuitive observation where the exciton density at which EEA dominates is higher in materials with larger EEA coefficients.
Article
Multidisciplinary Sciences
Satyendra Nath Gupta, Ora Bitton, Tomas Neuman, Ruben Esteban, Lev Chuntonov, Javier Aizpurua, Gilad Haran
Summary: Plasmonic cavities can confine electromagnetic radiation to deep sub-wavelength regimes, allowing for strong coupling phenomena with individual quantum emitters. By studying scattering spectra and using interferometry, researchers observed Rabi splitting and non-classical emission in devices with semiconductor quantum dots, revealing complex interactions between bright and dark states. Model simulations based on an extended Jaynes-Cummings Hamiltonian explained the experimental findings, highlighting the potential of controlling quantum state dynamics through the coupling of quantum emitters to plasmonic cavities.
NATURE COMMUNICATIONS
(2021)
Article
Chemistry, Multidisciplinary
Shiekh Zia Uddin, Naoki Higashitarumizu, Hyungjin Kim, Eran Rabani, Ali Javey
Summary: Exciton-exciton annihilation in monolayer TMDCs can be controlled by strain. In bilayer WSe2, a nonmonotonic change in EEA rate at high generation rates is observed, accompanied by a significant enhancement in PL QY at low generation rates. By strain and electrostatic counterdoping, similar to 50% PL QY can be achieved in 2L WSe2 at all generation rates.
Article
Chemistry, Multidisciplinary
Jie Zhang, Hayato Sakai, Katsuaki Suzuki, Taku Hasobe, Nikolai Tkachenko, I-Ya Chang, Kim Hyeon-Deuk, Hironori Kaji, Toshiharu Teranishi, Masanori Sakamoto
Summary: Researchers have achieved near-unity singlet fission by assembling Pc chromophores on nanosized CdTe quantum dots, leading to suppression of triplet-triplet annihilation and efficient light-harvesting. The unique arrangement of Pc on the quantum dots surface plays a key role in realizing the singlet fission, with rapid dissociation of triplet pairs contributing to long-lived triplets.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Materials Science, Multidisciplinary
Mengqi Lin, Xizhen Zhang, Lizhu Guo, Yuhang Zhang, Ruixin Song, Sai Xu, Huichao Zhu, Chuanhui Cheng, Yongze Cao, Yichao Wang, Baojiu Chen
Summary: Blue and green light emitting CsPbBr3 and CsPb(Cl/Br)(3) perovskite quantum dots glasses have been fabricated with adjustable emission wavelengths and high photoluminescence quantum yield. As the Cl/Br ratio increases, the emission lifetime decreases, the average lifetime decreases, and the photoluminescence quantum yield also significantly decreases. Temperature dependence of PL spectra shows a decrease in integrated intensity with increasing temperature, while emission peak wavelength and FWHM remain almost unchanged.
Editorial Material
Chemistry, Physical
Naomi S. Ginsberg, William A. Tisdale
Summary: Early time transient absorption microscopy in quantum dot solids reveals different temporal regimes of exciton transport within hundreds of femtoseconds after photoexcitation.
Article
Chemistry, Physical
Xiuqing Bai, Huiyu Li, Yonggang Peng, Guofeng Zhang, Changgang Yang, Wenli Guo, Xue Han, Jialu Li, Ruiyun Chen, Chengbing Qin, Jianyong Hu, Gaoling Yang, Haizheng Zhong, Liantuan Xiao, Suotang Jia
Summary: This study investigates the effect of aspect ratios of CdS nanorods on the photoluminescence emission of CdSe/CdS dot-in-rod nanocrystals using single-dot photoluminescence spectroscopy. The results show that as the aspect ratio increases, the photoluminescence quantum yield and lifetime decrease, while photoluminescence blinking is suppressed and the effect on the photoluminescence spectrum is less significant.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Chemistry, Multidisciplinary
Taek Joon Kim, Sang-hun Lee, Eunji Lee, Changwon Seo, Jeongyong Kim, Jinsoo Joo
Summary: In this study, the energy band alignments of a heterostructure consisting of MAPbI(3) perovskite sheets and CdSe-ZnS core-shell quantum dot layers were modulated, leading to the emission of far-red interlayer excitons. These excitons exhibited a longer lifetime and strong dipole alignment at the heterojunction. An abnormal behavior of the optical characteristics near the phase transition temperature of MAPbI(3) was observed. Photodetectors based on MAPbI(3)/CdSe-ZnS-QD heterostructures showed increased photocurrent and detectivity compared to MAPbI(3) under interlayer exciton excitation.
Article
Nanoscience & Nanotechnology
Ting-Yuan Chang, Hyunseok Kim, William A. Hubbard, Khalifa M. Azizur-Rahman, Jung Jin Ju, Je-Hyung Kim, Wook-Jae Lee, Diana Huffaker
Summary: This article reports on the monolithic integration of InAsP quantum dots embedded in InP nanowires on silicon, showing potential for building next-generation quantum light sources.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Chemistry, Multidisciplinary
Shiekh Zia Uddin, Naoki Higashitarumizu, Hyungjin Kim, Jun Yi, Xiang Zhang, Daryl Chrzan, Ali Javey
Summary: Dominant recombination pathways in monolayer TMDCs depend on background carrier concentration, generation rate, and strain. In this study, the diffusion of neutral and charged excitons in TMDCs is decoupled using chemical counterdoping and the effects of strain and generation rate on exciton diffusion are explored. It is found that increasing generation rate shortens exciton lifetime but increases diffusion length in unstrained monolayers of TMDCs. Strain suppresses exciton-exciton annihilation and makes both lifetime and diffusion length independent of generation rate.
Article
Chemistry, Multidisciplinary
Giovanni V. Resta, Lorenzo Stasi, Matthieu Perrenoud, Sylvain El-Khoury, Tiff Brydges, Rob Thew, Hugo Zbinden, Felix Bussieres
Summary: Superconducting nanowire single-photon detectors (SNSPDs) with high system detection efficiency (SDE), low dark counts, and fast recovery time have enabled the realization of various quantum optics technologies. This article presents an SNSPD array composed of 14 independent pixels, achieving an SDE of 90% in the telecommunications band. By reading each pixel of the array independently, the detection of telecommunication photons at 1.5 GHz with 45% absolute SDE is demonstrated. The dynamic photon-number resolution of the array is exploited for accurate state reconstruction of a wide range of light inputs, including long-duration light pulses obtained with cavity-based sources. Two-photon and three-photon fidelities of 74% and 57% are shown, respectively, representing state-of-the-art results for fiber-coupled SNSPDs.
Article
Nanoscience & Nanotechnology
Jian-Fu Tang, Yi-Da Sie, Zong-Liang Tseng, Ja-Hon Lin, Lung-Chien Chen, Cheng-Liang Hsu
Summary: In this study, a photodetector and humidity sensor based on zinc oxide nanowires (ZnO NWs) with CsPbBr3 perovskite quantum dots (PQDs) were developed. The excellent optoelectronic properties of PQDs make them ideal for semiconductor sensors. The experimental results showed that the performance of PQD/ZnO NWs was superior to that of ZnO NWs, especially in terms of humidity response and photocurrent.
ACS APPLIED NANO MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Christian Heyn, Andreas Grafenstein, Geoffrey Pirard, Leonardo Ranasinghe, Kristian Deneke, Ahmed Alshaikh, Gabriel Bester, Wolfgang Hansen
Summary: Strain-free GaAs quantum dots were fabricated by filling droplet-etched nanoholes in AlGaAs. The size of the quantum dots was precisely controlled by the thickness of the GaAs filling layer. Various characteristics of the quantum dots were studied using single-dot photoluminescence measurements, and the results were interpreted using an atomistic model.