Engineering interfacial structure in “Giant” PbS/CdS quantum dots for photoelectrochemical solar energy conversion

Liu, Jin; Sirigu, Gianluca; Tong, Xin; Camellini, Andrea; Parisini, A.; Nicotra, Giuseppe; Spinella, C.; Zhao, Haiguang; Sun, Shuhui; Morandi, Vittorio; Zavelani‐Rossi, M.; Rosei, Federico; Vomiero, Alberto

doi:10.1016/j.nanoen.2016.10.029

Cited by 92 publications

(99 citation statements)

References 68 publications

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“…In addition, as the BiOI ratio increases, the light absorption edge of the heterojunction photocatalyst extends to the visible region . For example, a light absorbing edge of the TBA‐1 heterostructure was observed at approximately 500 nm, indicating a response in the visible light region . It is noteworthy that the TBA‐2 heterostructure exhibits a better optical response than the TBA‐3 heterostructure, which is very consistent with the PC activity.…”

Section: Resultssupporting

confidence: 62%

“…34 For example, a light absorbing edge of the TBA-1 heterostructure was observed at approximately 500 nm, indicating a response in the visible light region. 35 It is noteworthy that the TBA-2 heterostructure exhibits a better optical response than the TBA-3 heterostructure, which is very consistent with the PC activity. The band gap of semiconductor synthesis can be calculated according to the equation: where α, ν, Eg, and A denote the absorption coefficient, optical frequency, band gap, and constant, respectively.…”

Section: Uv-visible Spectrasupporting

confidence: 70%

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Enhancement of photocatalytic and photoelectrochemical properties of BiOI nanosheets and silver quantum dots co‐modified TiO₂ nanorod arrays

et al. 2019

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In this study, TiO2 nanorod arrays (TNR), Ag quantum dots (QDs) sensitized with TNR TiO2/Ag, bismuth oxyhalide (BiOI) nanosheets, and Ag QDs co‐modified with TNR and TiO2/BiOI/Ag (TBA) were prepared by a stepwise process. The morphological, structural, compositional, optical, photocatalytic (PC), and photoelectrochemical (PEC) properties of the samples were investigated. The TBA‐2 sample exhibited the highest photocurrent density (281.8 μA/cm2) and photodegradation efficiency (93.3%), with values 9.7 times and 2.25 times higher than those for TNR, respectively. The improvement in sample performance can be attributed to the formation of a heterojunction between BiOI and TiO2, thereby enhancing the absorption of visible light and improving the charge separation efficiency; Ag QDs limit interfacial electron‐hole pair recombination. The experimental results show that TBA can effectively promote light‐induced carrier transport and visible light absorption, while inhibiting the recombination rate of the electron‐hole pairs, PEC, and PC.

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Section: Resultssupporting

confidence: 62%

Section: Uv-visible Spectrasupporting

confidence: 70%

Enhancement of photocatalytic and photoelectrochemical properties of BiOI nanosheets and silver quantum dots co‐modified TiO₂ nanorod arrays

et al. 2019

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“…Core/shell NCs with thin shell (which we will call core/TS NCs) were synthesized inducing the formation of a thin CdS shell through cation exchange; samples with a "giant" shell were obtained via a subsequent successive ionic layer absorption and reaction (SILAR) procedure at 240 • C under N 2 flow. To vary the core/shell interface the precursor Cd:S stoichiometric ratio was changed from 1:1 to 1:0.8 so as to have an abrupt [22] or alloyed transition [25], that is, a "sharp" or a "graded" interface. In the following we will refer to core/shell NCs with a giant shell as core/GSS and core/GGS correspondingly for sharp or graded interface.…”

Section: A Experimental Detailsmentioning

confidence: 99%

“…All samples were dispersed in toluene solution. The NCs were previously characterized [22,25] and showed a narrow size distribution. The core is identical for all cases [22,25] with a diameter of ∼1.2 nm.…”

Section: A Experimental Detailsmentioning

confidence: 99%

“…Shell emission seems favored by long pod or rod and large shell volume [12,14,15,19], where usually nonradiative Auger recombination is reduced or suppressed [12,16,18,24]. The most used and studied composition is the CdSe/CdS [12,[14][15][16][17]23] and very few different compositions have been explored [19,22,25] yet not fully investigated, despite the fact that they are very interesting because they operate in the spectral region close to the infrared. In very few cases rod and shell emission of CdSe/CdS NCs resulted in amplified spontaneous emission (ASE) [15,23] or even laser emission [26], giving additional advantageous properties to the NCs.…”

Section: Introductionmentioning

confidence: 99%

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Dual emission and optical gain in PbS/CdS nanocrystals: Role of shell volume and of core/shell interface

et al. 2017

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Colloidal semiconductor nanocrystals (NCs) emitting simultaneously at two distinct wavelengths are of great interest for multiple applications ranging from ultrasensitive self-calibrating nanoscale sensing to light-emitting diodes and white-light emission. The physical mechanism governing dual emission in core/shell NCs composed of two materials is still under investigation; in particular, the roles of the volume of the shell and of the core/shell interface are not well understood. Here we compare three different PbS/CdS NCs with identical cores, but shells of different thicknesses and different core/shell interfaces. We study photoluminescence (PL) characteristics and ultrafast exciton dynamics with subpicosecond time resolution. We find that dual emission is possible for both thick and thin quantum-confined shells, and for different core/shell interfaces. We show that very thick shells allow the decoupling of shell excitons from core ones and we fully describe the dynamic exciton barrier, connected to efficient shell PL. We discuss the efficiency of shell PL in relation to the properties of the NCs and show that it can give rise to optical gain. Our results provide a comprehensive understanding of the physical phenomena governing dual-emission mechanisms in NCs.

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Highly Stable Colloidal “Giant” Quantum Dots Sensitized Solar Cells

Selopal

Zhao

Tong

et al. 2017

Adv Funct Materials

105

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Colloidal quantum dots (QDs) are widely studied due to their promising optoelectronic properties. This study explores the application of specially designed and synthesized “giant” core/shell CdSe/(CdS)x QDs with variable CdS shell thickness, while keeping the core size at 1.65 nm, as a highly efficient and stable light harvester for QD sensitized solar cells (QDSCs). The comparative study demonstrates that the photovoltaic performance of QDSCs can be significantly enhanced by optimizing the CdS shell thickness. The highest photoconversion efficiency (PCE) of 3.01% is obtained at optimum CdS shell thickness ≈1.96 nm. To further improve the PCE and fully highlight the effect of core/shell QDs interface engineering, a CdSexS1−x interfacial alloyed layer is introduced between CdSe core and CdS shell. The resulting alloyed CdSe/(CdSexS1−x)5/(CdS)1 core/shell QD‐based QDSCs yield a maximum PCE of 6.86%, thanks to favorable stepwise electronic band alignment and improved electron transfer rate with the incorporation of CdSexS1−x interfacial layer with respect to CdSe/(CdS)6 core/shell. In addition, QDSCs based on “giant” core/CdS‐shell or alloyed core/shell QDs exhibit excellent long‐term stability with respect to bare CdSe‐based QDSCs. The giant core/shell QDs interface engineering methodology offers a new path to improve PCE and the long‐term stability of liquid junction QDSCs.

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Engineering interfacial structure in “Giant” PbS/CdS quantum dots for photoelectrochemical solar energy conversion

Cited by 92 publications

References 68 publications

Enhancement of photocatalytic and photoelectrochemical properties of BiOI nanosheets and silver quantum dots co‐modified TiO₂ nanorod arrays

Enhancement of photocatalytic and photoelectrochemical properties of BiOI nanosheets and silver quantum dots co‐modified TiO₂ nanorod arrays

Dual emission and optical gain in PbS/CdS nanocrystals: Role of shell volume and of core/shell interface

Highly Stable Colloidal “Giant” Quantum Dots Sensitized Solar Cells

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Engineering interfacial structure in “Giant” PbS/CdS quantum dots for photoelectrochemical solar energy conversion

Cited by 92 publications

References 68 publications

Enhancement of photocatalytic and photoelectrochemical properties of BiOI nanosheets and silver quantum dots co‐modified TiO2 nanorod arrays

Enhancement of photocatalytic and photoelectrochemical properties of BiOI nanosheets and silver quantum dots co‐modified TiO2 nanorod arrays

Dual emission and optical gain in PbS/CdS nanocrystals: Role of shell volume and of core/shell interface

Highly Stable Colloidal “Giant” Quantum Dots Sensitized Solar Cells

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Product

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Enhancement of photocatalytic and photoelectrochemical properties of BiOI nanosheets and silver quantum dots co‐modified TiO₂ nanorod arrays

Enhancement of photocatalytic and photoelectrochemical properties of BiOI nanosheets and silver quantum dots co‐modified TiO₂ nanorod arrays