Size-Dependent Composition and Molar Extinction Coefficient of PbSe Semiconductor Nanocrystals

Dai, Qiang; Wang, Yingnan; Li, Xinbi; Pellegrino, Donald J.; Zhao, Min; Zou, Bo; Seo, Jaetae; Wang, Yiding

doi:10.1021/nn9001616

Cited by 204 publications

(249 citation statements)

References 38 publications

Supporting

Mentioning

220

Contrasting

Unclassified

Order By: Relevance

“…Their first excitonic absorption peaks red-shifted from 1162 to 1577 nm, corresponding to an increase in size from ∼3.6 to ∼5.1 nm. 26 The absorption full width at half-maximum (fwhm; Gaussian-fitted) was ∼130-140 nm, and the particle number was low with the NC concentration [PbSe] in the reaction medium of ∼1.0-1.2 μmol/kg and the chemical yield of ∼1.1-2.8% (similar to that reported in 2006 and shown in Table 1). 30 [PbSe] was determined by Lambert-Beer's law, A = εCL, where the molar extinction coefficient ε was estimated from the PbSe NCs size and corrected by the size distribution (see the Experimental Methods section for details).…”

Section: Pbse Monomer ½Methods ð2þ ðBmþsupporting

confidence: 82%

“…Using Lambert-Beer's law, A = εCL, the nanocrystal molar concentration, C, was calculated, where ε, the molar extinction coefficient, was estimated from the PbSe size and corrected by size distribution. 26 The nanocrystal concentration, [PbSe], in the reaction mixture was back-calculated based on the weight of the aliquots taken. There is another method to get ε, where ε 3.1 eV is also size-dependent but irrespective of size distribution.…”

Section: ' Experimental Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Low-Temperature Approach to High-Yield and Reproducible Syntheses of High-Quality Small-Sized PbSe Colloidal Nanocrystals for Photovoltaic Applications

Ouyang¹,

Schuurmans²,

Zhang³

et al. 2011

ACS Appl. Mater. Interfaces

106

View full text Add to dashboard Cite

Small-sized PbSe nanocrystals (NCs) were syn-thesized at low temperature such as 50−80 °C with high reaction yield (up to 100%), high quality, and high synthetic reproducibility, via a noninjection-based one-pot approach. These small-sized PbSe NCs with their first excitonic absorption in wavelength shorter than 1200 nm (corresponding to size < ∼3.7 nm) were developed for photovoltaic applications requiring a large quantity of materials. These colloidal PbSe NCs, also called quantum dots, are high-quality, in terms of narrow size distribution with a typical standard deviation of ∼7−9%, excellent optical properties with high quantum yield of ∼50−90% and small full width at half-maximum of ∼130−150 nm of their band-gap photoemission peaks, and high storage stability. Our synthetic design aimed at promotion of the formation of PbSe monomers for fast and sizable nucleation with the presence of a large number of nuclei at low temperature. For formation of the PbSe monomer, our low-temperature approach suggests the existence of two pathways of Pb−Se (route a) and Pb−P (route b) complexes. Either pathway may dominate, depending on the method used and its experimental conditions. Experimentally, a reducing/nucleation agent, diphenylphosphine, was added to enhance route b. The present study addresses two challenging issues in the NC community, the monomer formation mechanism and the reproducible syntheses of small-sized NCs with high yield and high quality and large-scale capability, bringing insight to the fundamental understanding of optimization of the NC yield and quality via control of the precursor complex reactivity and thus nucleation/growth. Such advances in colloidal science should, in turn, promote the development of next-generation low-cost and high-efficiency solar cells. Schottky-type solar cells using our PbSe NCs as the active material have achieved the highest power conversion efficiency of 2.82%, in comparison with the same type of solar cells using other PbSe NCs, under Air Mass 1.5 global (AM 1.5G) irradiation of 100 mW/cm2.

show abstract

Section: Pbse Monomer ½Methods ð2þ ðBmþsupporting

confidence: 82%

Section: ' Experimental Methodsmentioning

confidence: 99%

Low-Temperature Approach to High-Yield and Reproducible Syntheses of High-Quality Small-Sized PbSe Colloidal Nanocrystals for Photovoltaic Applications

Ouyang¹,

Schuurmans²,

Zhang³

et al. 2011

ACS Appl. Mater. Interfaces

106

View full text Add to dashboard Cite

show abstract

“…This method is therefore to be preferred over a procedure based on the Qdot absorbance at the band gap. 12,17 PbS Qdot Optical Properties at the Band Gap. We calculate the molar extinction at the band gap gap by integrating the first absorption peak on an energy scale.…”

Section: Resultsmentioning

confidence: 99%

Size-Dependent Optical Properties of Colloidal PbS Quantum Dots

et al. 2009

View full text Add to dashboard Cite

We quantitatively investigate the size-dependent optical properties of colloidal PbS nanocrystals or quantum dots (Qdots) by combining-the Qdot absorbance spectra with detailed elemental analysis of the Qdot suspensions. At high energies, the molar extinction coefficient epsilon increases With the Not volume d(3) and agrees with theoretical calculations using the Maxwell-Garnett effective medium theory and bulk values for the Qdot dielectric function. This demonstrates that quantum confinement has no influence on E in this spectral range, and it provides an accurate method to calculate the Qdot concentration. Around the band gap, epsilon only increases with d(1.3), and values are comparable to the epsilon of PbSe Qdots. The data are related to the oscillator strength f(if) of the band gap transition and results agree well with theoretical tight-binding calculations, predicting a linear dependence of f(if) on d. For both PbS and PbSe Qdots, the exciton lifetime tau is calculated from f(if). We find values ranging between 1 and 3 mu s, in agreement with experimental literature data from time-resolved luminescence spectroscopy. Our results provide a thorough general framework to calculate and understand the optical properties of suspended colloidal quantum dots. Most importantly, it highlights the significance of the local field factor in these systems

show abstract

“…[1][2][3] These solids consist of macroscopic arrays of colloidally synthesized nanoparticles, wherein the band gap and the electronic properties of the composite array can be tuned by varying the size 4 and surface chemistry 5 of the constitutive elements, respectively. However, colloidally synthesized nanocrystals typically exhibit low impurity concentrations, 6 requiring post-synthetic treatments to effectively dope the nanocrystal solid.…”

mentioning

confidence: 99%

Controlled Chemical Doping of Semiconductor Nanocrystals Using Redox Buffers

2012

View full text Add to dashboard Cite

Semiconductor nanocrystal solids are attractive materials for active layers in next-generation optoelectronic devices; however, their efficient implementation has been impeded by the lack of precise control over dopant concentrations. Herein we demonstrate a chemical strategy for the controlled doping of nanocrystal solids under equilibrium conditions. Exposing lead selenide nanocrystal thin films to solutions containing varying proportions of decamethylferrocene and decamethylferrocenium incrementally and reversibly increased the carrier concentration in the solid by 2 orders of magnitude from their native values. This application of redox buffers for controlled doping provides a new method for the precise control of the majority carrier concentration in porous semiconductor thin films.

show abstract

Size-Dependent Composition and Molar Extinction Coefficient of PbSe Semiconductor Nanocrystals

Cited by 204 publications

References 38 publications

Low-Temperature Approach to High-Yield and Reproducible Syntheses of High-Quality Small-Sized PbSe Colloidal Nanocrystals for Photovoltaic Applications

Low-Temperature Approach to High-Yield and Reproducible Syntheses of High-Quality Small-Sized PbSe Colloidal Nanocrystals for Photovoltaic Applications

Size-Dependent Optical Properties of Colloidal PbS Quantum Dots

Controlled Chemical Doping of Semiconductor Nanocrystals Using Redox Buffers

Contact Info

Product

Resources

About