Diffusion length determination in thin-film Cu<i>x</i>S/CdS solar cells by scanning electron microscopy

Oakes, Jim; Greenfield, I. G.; Partain, L. D.

doi:10.1063/1.323971

Cited by 36 publications

(7 citation statements)

References 17 publications

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“…From the exponential fitting, the value of l D has been found to be $ 0.35 mm, which is close to the spatial resolution of SPCM measurements, and thus provides the upper limit of the minority diffusion length. This value is comparable to the reported values of minority carrier diffusion lengths of 0.11 and 0.57 mm in p-type CuS thin films [13].…”

Section: Resultssupporting

confidence: 90%

Photocurrent and photovoltaic characteristics of copper sulfide nanowires grown by a hydrothermal method

et al. 2014

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Section: Resultssupporting

confidence: 90%

Photocurrent and photovoltaic characteristics of copper sulfide nanowires grown by a hydrothermal method

et al. 2014

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“…Such fast separation of the photogenerated carriers can be explained by two facts. First, the diffusion length of carriers in CdS materials (such as bulk and polycrystals) is on the scale of at least tens of nanometers, [34,35] which is much greater than the diameter (about 5.1 nm) of the CdS nanorods. Second, the carrier capture by the CdSe QDs as well as the CdS surface is very efficient.…”

Section: Resultsmentioning

confidence: 99%

Selective Excitation of CdSe/CdS Dot‐in‐Rod Nanocrystals and Distinct Roles of Electrons and Holes in Photophysical and Photochemical Interactions with Ambient Air

Wang

Zheng

et al. 2021

Physica Status Solidi (b)

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CdSe/CdS dot‐in‐rod (DiR) nanocrystals are an advantageous heterostructured semiconductor system with a quasi‐type‐II electronic band structure, which enables a rich diversity of optical manipulation of carrier excitations and interactions. Herein, the selective excitation of respective CdSe quantum dots (QDs) and CdS nanorods of the CdSe/CdS DiR nanostructure is reported, which results in the distinct presence of different types of carriers at the nanorod surface. The presence of only electrons at the surface upon CdSe QD excitation leads to photophysical interactions with ambient air, which is manifested as reversible photoluminescence (PL) of the CdSe QDs. The excitation of CdS nanorods produces holes at the surface, which induces photooxidation of the CdS surface and irreversible change in PL intensity and spectral lineshape. Benefitting from unambiguously relating carrier types to photophysical and photochemical interactions, this research also verifies that trap states at the CdS surface do not act as nonradiative recombination centers, which can be removed by photochemical reactions. Herein, distinct roles of electrons and holes in the photophysical and photochemical interactions with ambient air are identified, and a more precise understanding of the interacting mechanisms is achieved.

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“…This is reasonable because C rad should be similar because they are all direct band gap semiconductors, and C Aug is similar for most semiconductors because it does not have strong dependence on band structure [3]. A possible range for the surface recombination velocity in CZTS, v , surf CZTS is proposed to be 10 3 −10 4 cms −1 [22], and the density of trapped states in μm [25] were measured. To do this, equation ( 15) is used to relate the diffusion lengths with the total carrier lifetimes, t , tot which is determined from equation (26).…”

Section: Modelling Solar Cell Layers Generating the Solar Spectrum An...mentioning

confidence: 99%

“…(25) respectively, where the required values N T CZTS and v surf CdS are calculated in equations (23) and(25) respectively. This calibration found = s −1 .…”

mentioning

confidence: 99%

Modelling an optimised thin film solar cell

Becque

Halliday

2019

Eur. J. Phys.

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A phenomenological model has been developed to simulate the efficiency of thin film solar cells. The model uses key equations for p-n heterojunctions and includes radiative recombination, Auger recombination, Shockley-Read-Hall recombination and surface recombination losses. This framework is appropriate for final year undergraduate and Masters students. Key solar cell phenomena are related to an equivalent circuit enabling the maximum conversion efficiency to be determined under standard AM1.5 solar illumination. The underlying physical basis of the model is presented together with algorithms to allow numerical simulation of a solar cell under the full range of operating conditions. The simulation accounts for optical losses within the device and uses a shunt resistance to account for recombination losses. Solar cells can be optimised for efficiency, or other operating characteristics, by adjusting layer thicknesses and doping levels. The model is used to investigate an emerging solar technology: thin-film p-n heterojunction Cu2ZnSnS4/CdS solar cells. An optimised solar cell is found to have an overall PV conversion efficiency of (10±1)%, however significant uncertainties on the values of some Cu2ZnSnS4 material properties mean that the trends predicted by the model are a more useful output from the simulation as these can be related to underlying physical phenomena in a solar cell. A region of maximum efficiency is found for absorber layer thicknesses of the order of microns. The range of CdS thicknesses for which this region is maximised is found when the n-type doping concentration of the CdS is maximised. An abrupt drop in efficiency is found when the CdS doping concentration is less than the doping in the Cu2ZnSnS4. Varying device and material parameters provides physical insights into the operation of solar cell devices. Strategies for managing optical losses and carrier losses can be tested leading to the identification of designs optimised for high efficiency thin film solar cells. The model can be used for other thin film PV technologies by inputting material properties.

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Diffusion length determination in thin-film CuxS/CdS solar cells by scanning electron microscopy

Cited by 36 publications

References 17 publications

Photocurrent and photovoltaic characteristics of copper sulfide nanowires grown by a hydrothermal method

Photocurrent and photovoltaic characteristics of copper sulfide nanowires grown by a hydrothermal method

Selective Excitation of CdSe/CdS Dot‐in‐Rod Nanocrystals and Distinct Roles of Electrons and Holes in Photophysical and Photochemical Interactions with Ambient Air

Modelling an optimised thin film solar cell

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