Article
Chemistry, Physical
Katherine E. Shulenberger, Helena R. Keller, Lauren M. Pellows, Niamh L. Brown, Gordana Dukovic
Summary: This study reports the discovery of photocharging of CdS nanocrystals under continuous wave illumination with no added reductants. The long-lived reduced states in CdS nanocrystals form under illumination and recover over time scales of minutes when illumination stops, which contrasts with the behavior of CdSe nanocrystals.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Chemistry, Physical
Gerard Michael Carroll, Rens Limpens, Gregory F. Pach, Yaxin Zhai, Matthew C. Beard, Elisa M. Miller, Nathan R. Neale
Summary: This study shows that changing the functional groups on the surface of silicon nanocrystals can slow Auger recombination rates, with thiolate groups elongating the recombination time. These findings highlight the potential positive impact of chemical species with mid-gap surface states under high-rate absorption/emission conditions.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Chemistry, Physical
Yujie Han, Yang Shen, Kongchao Shen, Zhenhuang Su, Yanqing Li, Fei Song, Xingyu Gao, Jian-Xin Tang
Summary: This study investigates the influence of the hole transport layer on charge transport and recombination processes in PeLEDs through impedance spectroscopy. The results show that rational interfacial energy level alignment can improve radiative recombination efficiency and enhance device performance.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Chemistry, Physical
Tasnim Ahmed, Sumanta Paul, Anunay Samanta
Summary: Lead halide perovskites are crucial for solar photovoltaic applications, and understanding the hole transfer process is essential for their performance. This study investigates the influence of hole transfer from FAPbBr(3) to phenothiazine on the photoluminescence blinking dynamics of nanocrystals. The results reveal the heterogeneous nature of the hole transfer dynamics and the formation of a short-lived charge-separated state.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Chemistry, Physical
Yonglei Sun, Hua Zhu, Na Jin, Ou Chen, Jing Zhao
Summary: Lifetime blinking, a phenomenon of fluctuations in the fluorescence lifetime of a single quantum dot over time while its fluorescence intensity remains relatively stable, has been reported in a few QD systems. In this study, statistical methods demonstrate that compact CdSe/CdS core/shell QDs also exhibit short-lived lifetime blinking events, possibly due to the activation of efficient nonradiative processes leading to intensity blinking.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Chemistry, Physical
Xiao-Yi Liu, Yu Cui, Jia-Pei Deng, Yi-Yan Liu, Xu-Fei Ma, Yu-Xuan Hou, Jun-Ye Wei, Zhi-Qing Li, Zi-Wu Wang
Summary: In this study, a method of a full-configuration defect based on the well-known Huang-Rhys model is developed to study the multiphonon processes of charge carrier trapping by various defects in metal halide perovskites quantum dots (MHPQDs). The trapping time dependence on the radius of quantum dot, defect depth, and temperature is investigated. These findings not only enhance our understanding of charge carrier trapping processes by defects, but also provide insights for the designs of MHPQDs-based photovoltaic and photoelectric devices.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Somnath Koley, Jiabin Cui, Yossef. E. Panfil, Yonatan Ossia, Adar Levi, Einav Scharf, Lior Verbitsky, Uri Banin
Summary: The charge redistribution upon optical excitation of various necked homodimer colloidal quantum dot molecules (CQDMs) is investigated using single-particle emission spectroscopy. By tuning the hybridization of the electron wavefunctions at a fixed center-to-center distance through controlling the neck girth, we reveal two coupling limits: weak-coupling regime and strong-coupling regime. The emitted photons from CQDMs in the weak-coupling regime show high bunching while the antibunching is regained at the strong-coupling regime.
Article
Chemistry, Multidisciplinary
Chang Yan, Daniel Weinberg, Dipti Jasrasaria, Matthew A. Kolaczkowski, Zi-jie Liu, John P. Philbin, Arunima D. Balan, Yi Liu, Adam M. Schwartzberg, Eran Rabani, A. Paul Alivisatos
Summary: Understanding electronic dynamics in multiexcitonic quantum dots is crucial for designing efficient systems in high power scenarios like solar concentrators and multielectron charge transfer. By synthesizing a phenothiazine derivative and using transient absorption spectroscopy, the competition between Auger recombination and hole transfer in CdSe, CdS, and CdSe/CdS QDs was investigated, revealing the beneficial role of hole-trapping states in enhancing hole transfer efficiency under multiexcitonic conditions.
Article
Chemistry, Multidisciplinary
Andre Maier, Fabian Strauss, Pia Kohlschreiber, Christine Schedel, Kai Braun, Marcus Scheele
Summary: The intrinsic response time and bandwidth of lead sulfide nanocrystal photodetectors were investigated using a two-pulse coincidence photoresponse technique. The results indicated an intrinsic response time of approximately 1 ns and an intrinsic bandwidth of approximately 0.55 GHz. Auger recombination assisted by nanocrystal surface defects was identified as the dominant mechanism. The intrinsic response time could be further tuned by controlling ligand coverage and trap states.
Article
Materials Science, Multidisciplinary
Andrew A. Marder, James Cassidy, Dulanjan Harankahage, Jacob Beavon, Luis Gutierrez-Arzaluz, Omar F. Mohammed, Aditya Mishra, Austen C. Adams, Jason. D. Slinker, Zhongjian Hu, Stephen Savoy, Mikhail Zamkov, Anton V. Malko
Summary: Compared to zero-dimensional (0D) semiconductor quantum dots, 2D semiconductor nanoplatelets (NPLs) offer a spectrally narrow luminescence and superior absorption coefficients. However, optical devices based on NPLs still suffer from nonradiative Auger decay, which limits the efficiency of various processes. In this study, it is demonstrated that Auger recombination is strongly suppressed in spherically shaped nanoplatelets called quantum shells (QSs), leading to improved performance in terms of biexciton emission yield, amplified spontaneous emission, and electroluminescence enhancement. These results are significant for the development of solution-processed colloidal lasers and LEDs.
ACS MATERIALS LETTERS
(2023)
Review
Chemistry, Multidisciplinary
Christopher Melnychuk, Philippe Guyot-Sionnest
Summary: Multicarrier dynamics in quantum dots are primarily governed by nonradiative Auger processes, impacting the performance of lasers, LEDs, and photodetectors, with implications in fluorescence intermittency phenomena. Understanding of Auger recombination, cooling, and carrier multiplication in quantum dots is important for enhancing device efficiency. Further research is needed to fully comprehend the complexities of multicarrier physics in quantum dots.
Article
Chemistry, Physical
Jayanta Dana, Tufan Ghosh, Itay Gdor, Arthur Shapiro, Efrat Lifshitz, Sanford Ruhman
Summary: The spectator exciton method is used to study the influence of the number of excitons on the absorption of nanocrystals by comparing their absorption spectra. The experiments show that in CdSe nanodots, conflicts in electron spin orientation result in the blocking of 50% of hot electrons from directly cooling to the band edge. In contrast, loading of cold excitons in PbS nanodots leads to a gradual broadening of the 1Se1Sh absorption band, indicating the inadequacy of using a single probe wavelength to measure the filling of band-edge states. Furthermore, the sub band gap induced absorption characteristic of hot exciton states in all quantum dots is not the low-energy half of biexciton shifting to the 1Se1Sh absorption band, but rather part of a broad induced absorption characteristic of hot excitons regardless of the spectator count. Finally, the unique capability of spectator excitons (SXs) to detect contributions of stimulated emission to pump-probe signals is demonstrated in singly excited PbS nanocrystals, where no such contributions are observed.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
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
Z. Ouzit, G. Baillard, J. Liu, B. Wagnon, L. Guillemeney, B. Abecassis, L. Coolen
Summary: This study compares the luminescence decay dynamics of single CdSe nanoplatelets, clusters of a few platelets, and self-assembled chains. The luminescence decay becomes faster as the number of stacked platelets increases, indicating the FRET-mediated effect of quenchers. Additionally, a slow decay component is observed for both single platelets and platelet chains, suggesting trapping-detrapping mechanisms in nearby trap states. Toy models are developed to analyze the effects of FRET-mediated quenching and trapping on decay curves.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Chemistry, Physical
Dong-Won Jeong, Tae-Hyeon Park, Jung Ho Lee, Du-Jeon Jang
Summary: The study investigated the efficient addition of X-type ligands to wurtzite CdSe QDs passivated with phosphonic acids using Z-type ligands. The results showed that a sufficient amount of the desired ligand can be introduced, substantially enhancing the quantum yields of CdSe QDs.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
