Barrier inhomogeneities in Au/CdSe thin film Schottky diodes

Panchal, C. J.; Desai, M.N.; Kheraj, Vipul; Patel, K. J.; Padha, Naresh

doi:10.1088/0268-1242/23/1/015003

Cited by 18 publications

(8 citation statements)

References 29 publications

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“…Although in one case CdSe is contacted directly with gold, the second case involves CdSe that is attached to TiO 2 , which then is in contact with gold. CdSe and TiO 2 are both known to form a Schottky barrier at the gold interface. ,, However, because the barrier height is similar in both cases, and no significant barrier for electron transfer from CdSe to TiO 2 is expected, we believe the addition of a TiO 2 layer to have a negligible effect on the charge extraction properties. The similarity in J SC for both types of devices supports this view.…”

Section: Resultsmentioning

confidence: 92%

Fabrication and Electrochemical Photovoltaic Response of CdSe Nanorod Arrays

et al. 2008

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CdSe nanorod electrode arrays with the nanorods aligned normal to the substrate were fabricated using porous aluminum oxide (PAO) templates. Photovoltaic characteristics were determined electrochemically in an aqueous solution using polysulfide (Sn 2−) as the redox mediator. Isolating the back electrode from the electrolyte with a 100-nm-thick TiO2 barrier layer increased the open circuit voltage from −0.23 to −0.34 V and the fill factor from 0.42 to 0.57. Depending on the electrolyte concentration, IPCE values between 2.5 and 8% were observed at an incident wavelength of 500 nm. Internal quantum efficiencies were estimated to approach 50%. This architecture could be beneficial for the fabrication of bulk-heterojunction photovoltaic devices in conjunction with solution-deposited semiconducting inorganic nanoparticles or organic semiconductors.

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Section: Resultsmentioning

confidence: 92%

Fabrication and Electrochemical Photovoltaic Response of CdSe Nanorod Arrays

et al. 2008

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“…From the reported EA, we expect an Ohmic contact between Ag and bulk CdSe, as Ohmic contacts have been observed in Cr/CdSe contacts (where Cr has a slightly higher work function than Ag). 35 For a CdSe QD, however, the QC induced shift of the CBM will lead to a Schottky barrier between the metal and QD, with a barrier height of ∼0.7 eV for a 30 Å QD and therefore expect rectifying behavior for a CdSe QD. In Fig.…”

Section: Electrical Conductivity Implicationsmentioning

confidence: 99%

Implications of orbital hybridization on the electronic properties of doped quantum dots: the case of Cu:CdSe

et al. 2016

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This paper investigates how chemical dopants affect the electronic properties of CdSe quantum dots (QDs) and why a model that incorporates the concepts of orbital hybridization must be used to understand these properties. Extended X-ray absorption fine structure spectroscopy measurements show that copper dopants in CdSe QDs occur primarily through a statistical doping mechanism. Ultraviolet photoemission spectroscopy (UPS) experiments provide a detailed insight on the valence band (VB) structure of doped and undoped QDs. Using UPS measurements, we are able to observe photoemission from the Cu d-levels above VB maximum of the QDs which allows a complete picture of the energy band landscape of these materials. This information provides insights into many of the physical properties of doped QDs, including the highly debated near-infrared photoluminescence in Cu doped CdSe QDs. We show that all our results point to a common theme of orbital hybridization in Cu doped CdSe QDs which leads to optically and electronically active states below the conduction band minimum. Our model is supported from current-voltage measurements of doped and undoped materials, which exhibit Schottky to Ohmic behavior with Cu doping, suggestive of a tuning of the lowest energy states near the Fermi level.

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“…It has become apparent that the electrical contacts to these active layers can significantly affect power conversion efficiencies. ,,− Both hole-collecting and electron-collecting electrodes need to be optimized in terms of their electrical uniformity, stability, conductivity, work function, physical compatibility with adjacent layers (e.g., wettability), and selective collection of the desired charge carrier (i.e., holes versus electrons) . In more mature inorganic solar cells both electrode specific and contact nonidealities have been shown to contribute to increases in the parasitic contact resistance ( R c ) and decreases in fill factor arising from enhanced rates of recombination. − The contribution to the total apparent R c of an OPV from the contact arises both from the bulk electrical properties of the electrode material and from surface specific contact effects, especially those arising from electrically inactive regions in the contacts over nanometer to micrometer length scales. ,, …”

Section: Introductionmentioning

confidence: 99%

Modeling the Effects of Molecular Length Scale Electrode Heterogeneity in Organic Solar Cells

Zacher

Armstrong

2011

J. Phys. Chem. C

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Kinetic Monte Carlo simulations of planar heterojunction (PHJ) organic solar cells (OPVs) constructed with electronically heterogeneous electrodes are presented which correlate the extent and length scale of electrode heterogeneity with their capacity for collecting photogenerated charge carriers. The PHJ OPV is modeled as an ensemble of discrete 1 nm3 molecular sites and 1 nm2 electrode sites for which we individually assign various effective activation energies for charge hopping. Utilizing Marcus theory to describe charge transfer reactions within the energetically disordered lattice, described by a Gaussian distribution of discrete site energies, we demonstrate the sensitivity of solar cell device performance to nanometer length scale heterogeneity at the electrode-active layer contact. Such sensitivity is reflected in the steady-state charge density profiles in the vicinity of the electrode-active material interface, charge collection efficiencies, and rates of recombination at the donor–acceptor (D/A) interface. Additionally, we demonstrate how implementation of idealized interlayers placed between the electrode and active layer functions to mitigate the negative effects of electrode heterogeneity.

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Barrier inhomogeneities in Au/CdSe thin film Schottky diodes

Cited by 18 publications

References 29 publications

Fabrication and Electrochemical Photovoltaic Response of CdSe Nanorod Arrays

Fabrication and Electrochemical Photovoltaic Response of CdSe Nanorod Arrays

Implications of orbital hybridization on the electronic properties of doped quantum dots: the case of Cu:CdSe

Modeling the Effects of Molecular Length Scale Electrode Heterogeneity in Organic Solar Cells

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