Synthesis of type II CdTe/CdSe heterostructure tetrapod nanocrystals for PV applications

Lee, H.; Yoon, Sungho; Ahn, Jungkyu; Suh, Yo‐Han; Lee, J.S.; Lim, Hyung‐Kyu; Kim, D.

doi:10.1016/j.solmat.2008.09.050

Cited by 33 publications

(16 citation statements)

References 12 publications

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“…The choice of the CdTe and CdSe systems is motivated by their already widespread use in current second generation thin film solar cells 7 and their potential use in third generation nanocrystal-or nanowire-based photo-voltaic architectures. 8 The attractiveness of these materials arises from their bandgap value, which falls within the solar spectrum, thereby enabling the efficient creation of electron-hole pairs (or excitons) by solar photons. Nevertheless, a major factor that controls the efficiency of photovoltaic systems is the efficient dissociation of photo-generated excitons.…”

Section: Introductionmentioning

confidence: 99%

Ab initio calculation of the CdSe/CdTe heterojunction band offset using the local-density approximation-1/2 technique with spin-orbit corrections

Ribeiro¹,

Fonseca

Sadowski

et al. 2012

Journal of Applied Physics

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We performed ab initio calculations of the electronic structures of bulk CdSe and CdTe and of their interface. We employed the local-density approximation-1/2 self-energy correction scheme [L. G. Ferreira, M. Marques, and L. K. Teles, Phys. Rev. B 78, 125116 (2008)] to obtain improved band gaps and band offsets, as well as spin-orbit coupling to further correct the valence band edges. Our results are in good agreement with experimental values for bulk band gaps and reproduce the staggered band alignment characteristic of this system. We found that the spin-orbit effect is of considerable importance for the bulk band gaps, but has little impact on the band offset of this particular system. Moreover, the electronic structure calculated along the 61.4 Å transition region across the CdSe/CdTe interface shows a non-monotonic variation of the bandgap in the range 0.8-1.8 eV. This finding may have important implications to the absorption of light along the interface between these two materials in photovoltaic applications. V

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Section: Introductionmentioning

confidence: 99%

Ab initio calculation of the CdSe/CdTe heterojunction band offset using the local-density approximation-1/2 technique with spin-orbit corrections

Ribeiro¹,

Fonseca

Sadowski

et al. 2012

Journal of Applied Physics

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“…The tetrapod limbs were approximately ∼26 nm long and ∼7 nm thick. Figure 1(b) shows the lattice fringes of the CdSe tetrapods with fringe spacing of 0.34 nm, corresponding to the (002) planes for the wurtzite structure of CdSe [18].…”

Section: Resultsmentioning

confidence: 99%

Structural and Optoelectronic Properties of CdSe Tetrapod Nanocrystals for Bulk Heterojunction Solar Cell Applications

Truong

Nguyen

Park

2013

International Journal of Photoenergy

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Semiconducting CdSe tetrapod nanoparticles were prepared, and their structural and optical properties were examined. The surface capping molecule, octylphosphonic acid, was replaced with butylamine after the particle synthesis. The exchange of surface ligands changed the physical properties of the nanocrystals, which resulted in a slight decrease in the nanoparticles size. The effects of changing surface ligands of CdSe tetrapod nanocrystals on the structural and optoelectronic properties were investigated, and it was found that the surfactant of nanoparticles could affect the device performance by enhancing the charge carrier separation at the active layer interfaces. Power conversion efficiency of the bulk heterojunction solar cells having the structure of glass/ITO/PEDOT:PSS/(CdSe + PCPDTBT)/Al was improved from 1.21% to 1.52% with the use of ligand-exchanged nanoparticles.

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“…Combination of heterostructures form II-VI semiconductors promises the techniques for ''band engineering''. Heterostructure multilayer thin films result in the formation of type I and type II band alignments (Lee et al 2009) as shown in Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

“…Type II heterostructure nanocrystals spatially separates photo-generated carriers within the nanostructure such that the electron wave function mainly resides in one semiconductor and hole wave function in the other (Milliron et al 2004). Recent investigations of type II CdTe/CdSe heterostructure nanocrystallites are ideal materials for their long range photo-induced charge separation and could be applied in photovoltaic devices (Lee et al 2009;Kumar et al 2007;Peng et al 2005). CdSe, CdTe and CdTe/CdSe tetrapod nanocrystals perform well in nanocrystal-polymer hybrid solar cells (Huynh et al 2002;Sun et al 2003;Gur et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Structural and optical properties of CdTe/CdSe heterostructure multilayer thin films prepared by physical vapor deposition technique

Kumar

Devadason

2012

Appl Nanosci

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CdTe/CdSe heterostructure multilayer thin films and single layers of CdSe and CdTe thin films were prepared. Sequential thermal evaporation technique is made possible to adjust the layer thickness precisely. XRD studies were used to calculate average size of the crystallites and confirmed the (111) and (100) planes of CdTe and CdSe, respectively. Bulk CdTe has band gap energy of 1.54 eV that can be shifted to larger values by reducing the crystallite size to dimensions smaller than the Bohr radius of the exciton. Experimentally measured energy levels show the spin-orbit split of valance band of CdTe. Crystallite sizes (7-12 nm) were calculated with the predictions of effective mass approximation model (i.e., Brus model) which shows that the diameter of crystallites were much smaller than the Bohr exciton diameter (14 nm) of CdTe. It is found that the emission peaks of the prepared CdTe/ CdSe ML samples were shifted from the peaks of CdSe and CdTe single layers toward red region as a characteristic of type II band alignment.

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Synthesis of type II CdTe/CdSe heterostructure tetrapod nanocrystals for PV applications

Cited by 33 publications

References 12 publications

Ab initio calculation of the CdSe/CdTe heterojunction band offset using the local-density approximation-1/2 technique with spin-orbit corrections

Ab initio calculation of the CdSe/CdTe heterojunction band offset using the local-density approximation-1/2 technique with spin-orbit corrections

Structural and Optoelectronic Properties of CdSe Tetrapod Nanocrystals for Bulk Heterojunction Solar Cell Applications

Structural and optical properties of CdTe/CdSe heterostructure multilayer thin films prepared by physical vapor deposition technique

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