Article
Chemistry, Multidisciplinary
Shijia Zeng, Zhenbo Li, Wenjiang Tan, Jinhai Si, Yuren Li, Xun Hou
Summary: This study compares the ultrafast carrier dynamics in InP/ZnSe/ZnS core/shell/shell quantum dots (CSS-QDs) and InP/ZnS core/shell QDs (CS-QDs), revealing the impact of the ZnSe midshell on carrier dynamics. The results show that the ZnSe midshell enhances electron delocalization, prolongs the in-band relaxation time of electrons and holes, and reduces defect emissions. Additionally, the ZnSe midshell leads to an increased density of higher-energy hole states, which may decrease the probability of Auger recombination.
Article
Chemistry, Physical
Paul Cavanaugh, Ilan Jen-La Plante, Christian Ippen, Ruiqing Ma, David F. Kelley, Anne Myers Kelley
Summary: Resonance Raman spectra and absolute cross sections of InP/ZnSe/ZnS core/shell/shell nanocrystals were obtained at different excitation wavelengths, revealing differences in phonon features attributed to various stoichiometries of the structures. The presence of excess indium in the ZnSe shell was found to influence the Raman intensities and frequency distributions, supporting previous assignments of hole trapping at indium defects in the shell.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Chemistry, Physical
Shijia Zeng, Zhenbo Li, Wenjiang Tan, Jinhai Si, Yuren Li, Xun Hou
Summary: The hole transfer process from the core to the surface in InP/ZnS and InP/ZnSe/ZnS quantum dots was studied comparatively using ultrafast spectroscopy and time-resolved photoluminescence technology. The results show that InP/ZnSe/ZnS quantum dots have a faster hole transfer rate with a ZnSe midshell thickness of about 2.2 nm. This is because the ZnSe midshell increases the density of higher-energy hole states, allowing a larger proportion of photoexcited holes to be distributed in these states compared to InP/ZnS quantum dots. The easier hole transfer in these higher-energy states makes InP/ZnSe/ZnS quantum dots more suitable for photoelectric conversion systems than InP/ZnS quantum dots.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Chemistry, Multidisciplinary
Dong-gu Kang, Yu-Ho Won, Chanho Park, Yongseok Han, Sang Kyu Kim
Summary: This study investigates the ultrafast charge carrier dynamics and hole-relaxation dynamics of green-light emitting InP/ZnSe/ZnS core-shell quantum dots with different ZnSe thicknesses using femtosecond transient absorption and stimulated Raman spectroscopy. The results show that the state-filling to the band-edge level of InP is slowed down with the increase of ZnSe mid-shell thickness. The hole-relaxation dynamics are revealed to be little sensitive to the ZnSe shell thickness.
ADVANCED MATERIALS INTERFACES
(2023)
Article
Chemistry, Multidisciplinary
Akihito Okamoto, Haruki Bai, Shintaro Toda, Maowei Huang, Hirotake Kajii, Kentaro Kawai, Hirohiko Murakami
Summary: The effect of ZnSe thickness on the properties of green-emitting InP/ZnSe/ZnS QDs was investigated. It was found that an optimum thickness of 1.2 nm for the ZnSe intermediate shell resulted in the narrowest full width at half maximum (FWHM) and highest photoluminescence quantum yield (PLQY). Excessive or insufficient ZnSe thickness broadened FWHM and decreased PLQY.
Article
Chemistry, Physical
Hongyang Zhao, Xin Li, Mengke Cai, Cheng Liu, Yimin You, Rui Wang, Ali Imran Channa, Feng Lin, Da Huo, Guofeng Xu, Xin Tong, Zhiming M. Wang
Summary: A controllable Cu shell doping approach has been reported to enhance the optoelectronic properties of InP/ZnSe core/shell quantum dots for high performance and stable solar energy conversion. The Cu-doped core/shell QDs exhibit improved photo-induced electron transfer rate and enhanced photocurrent density and long-term durability. The results suggest that Cu doping in the shell has a significant impact on the optoelectronic properties of the core/shell QDs, potentially opening up new avenues for customized eco-friendly QDs for efficient solar energy conversion.
ADVANCED ENERGY MATERIALS
(2021)
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
Nanoscience & Nanotechnology
Jiabin Liu, Shuai Yue, Hui Zhang, Chao Wang, David Barba, Francois Vidal, Shuhui Sun, Zhiming M. M. Wang, Jiming Bao, Haiguang Zhao, Gurpreet Singh Selopal, Federico Rosei
Summary: In this study, giant InP/ZnSe core/shell quantum dots (QDs) with tunable ZnSe shell thickness were synthesized to investigate the effect of the shell thickness on the optoelectronic properties and photoelectrochemical (PEC) performance. The results showed that the growth of ZnSe shell facilitated the delocalization of electrons and holes into the shell region and acted as a passivation layer to protect the surface of InP QDs while extracting photoexcited electrons and holes. Therefore, engineering the ZnSe shell thickness is crucial for tuning the optoelectronic properties of giant InP/ZnSe core/shell QDs.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Chemistry, Multidisciplinary
Taehee Kim, Yu-Ho Won, Eunjoo Jang, Dongho Kim
Summary: The study reveals that the Auger recombination processes of InP/ZnSe/ZnS quantum dots are influenced by the midshell structures, ultimately affecting the performance of QD-LEDs. The midshell thickness impacts the exciton-exciton binding energy and the negative trion Auger recombination behavior.
Article
Chemistry, Physical
Jiajia Ning, Yuan Xiong, Stephen Kershaw, Andrey L. Rogach
Summary: The most efficient way to improve the stability and optical properties of nanocrystals is to grow shell around their cores. Different growth modes of the ZnS shell on ZnSe nanorods were observed depending on the crystal structure of the ZnSe core, leading to differences in photoluminescence quantum yield.
CHEMISTRY OF MATERIALS
(2021)
Article
Chemistry, Physical
Paulina Jaimes, Tsumugi Miyashita, Tian Qiao, Kefu Wang, Ming Lee Tang
Summary: In this study, an inverse Type-I heterostructure with an inner InP shell was used for triplet-triplet annihilation-based photon upconversion. The addition of a ZnS shell on ZnSe/InP core/shell particles increased the photoluminescence quantum yield and transmitter triplet lifetime, while decreasing the rate of triplet energy transfer. The photon upconversion quantum yield of the ZnSe/InP/ZnS nanocrystals was found to be around 4.0%, suggesting their potential for converting near-infrared photons to visible light.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Chemistry, Physical
Paulina Jaimes, Tsumugi Miyashita, Tian Qiao, Kefu Wang, Ming Lee Tang
Summary: In this work, nanocrystals with an inner InP shell were used for triplet-triplet annihilation-based photon upconversion. The InP-based nanocrystals are earth-abundant and can be synthetically tuned to absorb in the NIR window. A two monolayer ZnS shell was used to passivate surface defects and improve the photoluminescence quantum yield of the InP nanocrystals. The ZnSe/InP/ZnS nanocrystals showed promising results in photon upconversion and can potentially convert NIR photons to visible light.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Chemistry, Physical
Jiakuan Zhang, Chuyue Li, Jiongzhao Li, Xiaogang Peng
Summary: Size- and shape-controlled CdSe/ZnSe core/shell and CdSe/ZnSe/ZnS core/shell/shell nanocrystals with zinc-blende structure are synthesized. The ligand strain between the inorganic crystal surface and organic ligands plays a key role in ZnSe epitaxy. The lattice strain between the CdSe and ZnSe affects the photoluminescence of CdSe/ZnSe/ZnS core/shell/shell QDs.
CHEMISTRY OF MATERIALS
(2023)
Article
Chemistry, Physical
Shijia Zeng, Wenjiang Tan, Jinhai Si, Liuhao Mao, Jinwen Shi, Yuren Li, Xun Hou
Summary: Through ultrafast spectroscopy, it was found that InP/ZnSe/ZnS core/shell/shell quantum dots exhibit better electron transfer capability compared to InP/ZnS quantum dots, as the introduction of ZnSe midshell improves passivation and enhances exciton delocalization. Temperature-dependent PL spectra indicate that the exciton-phonon coupling strength and exciton binding energy of InP/ZnSe/ZnS quantum dots are smaller. Further photocatalytic hydrogen evolution testing shows that InP/ZnSe/ZnS quantum dots have significantly higher photocatalytic activity and improved stability.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Jumi Park, Taehee Kim, Dongho Kim
Summary: Surface passivation is crucial for preventing oxidation and improving the emission properties of nanocrystal quantum dots (QDs). Recent studies have revealed the critical role of surface ligands in determining the performance of InP/ZnSe/ZnS QD-LEDs. The length of the ligand chain influences charge injection and inter-QD energy transfer dynamics, shedding new light on the importance of surface ligands for QD-LED applications.
