Uncovering Forbidden Optical Transitions in PbSe Nanocrystals

Peterson, Jeffrey J.; Huang, Libai; Delerue, Christophe; Allan, G.; Krauss, Todd D.

doi:10.1021/nl072487g

Cited by 52 publications

(70 citation statements)

References 26 publications

(67 reference statements)

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“…[13] have contributed this peak to the photon assisted S-P transition. In similar studies as reported in [14], experimentally observed absorption peaks were at 0.91 eV, 1.175 eV and 1.42 eV, out of which the first peak and the third peak were devoted to the single photon absorption process of l S h → l S e and l P h → l P e , respectively. Interestingly, they observed the second absorption peak for both single photon absorption as well as the two photon absorption processes.…”

Section: Discussionsupporting

confidence: 81%

Linear and nonlinear optical properties of the PbSe quantum dots doped germano-silica glass optical fiber

Watekar

Lin

et al. 2010

Journal of Non-Crystalline Solids

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Section: Discussionsupporting

confidence: 81%

Linear and nonlinear optical properties of the PbSe quantum dots doped germano-silica glass optical fiber

Watekar

Lin

et al. 2010

Journal of Non-Crystalline Solids

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“…For maximum size focusing and minimal Ostwald ripening, the optimum time for terminating the reaction was 5-6 min after CdCl 2 injection (Figure 1 a). This protocol produced NCs with well-defi ned 1st, 2nd, and 3rd excitonic transitions [63][64][65] (Figure S1, Supporting Information). To eliminate the effects of size distribution when comparing passivated and unpassivated samples, we ensured that both NC samples have the same HWHMs (Table S1, Supporting Information).…”

Section: Synthesis Characterization and Stability Of Pbse Ncsmentioning

confidence: 99%

Role of PbSe Structural Stabilization in Photovoltaic Cells

Asil

Walker

Ehrler

et al. 2014

Adv Funct Materials

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Semiconductor nanocrystals are promising materials for printed optoelectronic devices, but their high surface areas are susceptible to forming defects that hinder charge carrier transport. Furthermore, correlation of chalcogenide nanocrystal (NC) material properties with solar cell operation is not straightforward due to the disorder often induced into NC films during processing. Here, an improvement in long‐range ordering of PbSe NCs symmetry that results from halide surface passivation is described, and the effects on chemical, optical, and photovoltaic device properties are investigated. Notably, this passivation method leads to a nanometer‐scale rearrangement of PbSe NCs during ligand exchange, improving the long‐range ordering of nanocrystal symmetry entirely with inorganic surface chemistry. Solar cells constructed with a variety of architectures show varying improvement and suggest that triplet formation and ionization, rather than carrier transport, is the limiting factor in singlet fission solar cells. Compared to existing protocols, our synthesis leads to PbSe nanocrystals with surface‐bound chloride ions, reduced sub‐bandgap absorption and robust materials and devices that retain performance characteristics many hours longer than their unpassivated counterparts.

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“…3b,c we display a typical absorption spectrum of PbSe NCs and its second derivative. We assign the optical transitions according to the selection rules between symmetric wavefunctions determined by Kang and Wise [14,32]; the first transition is the 1S e -1S h transition, and the second transition has been a source of controversy [33,34] because within the k · p description this transition is assigned to a symmetry forbidden 1S e -1P h /1S h -1P e transition. Each pair of states has a high level of degeneracy that increases …”

Section: Introduction To Semiconductor Ncsmentioning

confidence: 99%

Multiple exciton generation in semiconductor nanocrystals: Toward efficient solar energy conversion

Beard¹,

Ellingson²

2008

Laser & Photonics Reviews

136

131

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Within the range of photon energies illuminating the Earth's surface, absorption of a photon by a conventional photovoltaic semiconductor device results in the production of a single electron-hole pair; energy of a photon in excess of the semiconductor's bandgap is efficiently converted to heat through electron and hole interactions with the crystal lattice. Recently, colloidal semiconductor nanocrystals and nanocrystal films have been shown to exhibit efficient multiple electron-hole pair generation from a single photon with energy greater than twice the effective band gap. This multiple carrier pair process, referred to as multiple exciton generation (MEG), represents one route to reducing the thermal loss in semiconductor solar cells and may lead to the development of low cost, high efficiency solar energy devices. We review the current experimental and theoretical understanding of MEG, and provide views to the nearterm future for both fundamental research and the development of working devices which exploit MEG. MEG E g E hνAbsorption of a single photon with energy in excess of two times the band gap, Eg, produces multiple excitons at the band edge. TEM picture of typical PbSe nanocrystals.

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Uncovering Forbidden Optical Transitions in PbSe Nanocrystals

Cited by 52 publications

References 26 publications

Linear and nonlinear optical properties of the PbSe quantum dots doped germano-silica glass optical fiber

Linear and nonlinear optical properties of the PbSe quantum dots doped germano-silica glass optical fiber

Role of PbSe Structural Stabilization in Photovoltaic Cells

Multiple exciton generation in semiconductor nanocrystals: Toward efficient solar energy conversion

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