Doping of polycrystalline CdTe for high-efficiency solar cells on flexible metal foil

Kranz, Lukas; Gretener, Christina; Perrenoud, J.; Schmitt, Rafael; Pianezzi, Fabian; Mattina, Fabio La; Blösch, P.; Cheah, Erik; Chirilă, A.; Fella, C.M.; Hagendorfer, Harald; Jäger, Timo; Nishiwaki, Shiro; Uhl, Alexander R.; Buecheler, Stephan; Tiwari, Ayodhya N.

doi:10.1038/ncomms3306

Cited by 246 publications

(164 citation statements)

References 32 publications

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“…The resistivity of the pure CdTe with different amounts of Cu added is comparable with previously published results [30]. A substantial increase in resistivity is observed if less than approximately 1 × 10 15 copper atoms/cm 2 are added.…”

Section: Resultssupporting

confidence: 89%

Structural and electronic properties of CdTe_1-xSe_x films and their application in solar cells

Lingg

Spescha

Haass

et al. 2018

Science and Technology of Advanced Materials

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The performance improvement of conventional CdTe solar cells is mainly limited by doping concentration and minority carrier life time. Alloying CdTe with an isovalent element changes its properties, for example its band gap and behaviour of dopants, which has a significant impact on its performance as a solar cell absorber. In this work, the structural, optical, and electronic properties of CdTe1-xSex films are examined for different Se concentrations. The band gap of this compound changes with composition with a minimum of 1.40 eV for x = 0.3. We show that with increasing x, the lattice constant of CdTe1-xSex decreases, which can influence the solubility of dopants. We find that alloying CdTe with Se changes the effect of Cu doping on the p-type conductivity in CdTe1-xSex, reducing the achievable charge carrier concentration with increasing x. Using a front surface CdTe1-xSex layer, compositional, structural and electronic grading is introduced to solar cells. The efficiency is increased, mostly due to an increase in the short-circuit current density caused by a combination of lower band gap and a better interface between the absorber and window layer, despite a loss in the open-circuit voltage caused by the lower band gap and reduced charge carrier concentration.

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Section: Resultssupporting

confidence: 89%

Structural and electronic properties of CdTe_1-xSe_x films and their application in solar cells

Lingg

Spescha

Haass

et al. 2018

Science and Technology of Advanced Materials

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“…[10][11][12][13] In this method, the electron beam of a scanning electron microscope (SEM) is used to generate excited charge carriers that are, in turn, collected as a measurable current for producing two-dimensional maps of the SCE. Although this method has yielded important insights into charge transport mechanisms in thin-film PV cells, the need for cross-section lamellas and operation in vacuum conditions make it destructive and render it difficult to evaluate devices under real operating conditions.…”

Section: Context and Scalementioning

confidence: 99%

The Spatial Collection Efficiency of Charge Carriers in Photovoltaic and Photoelectrochemical Cells

Segev

Dotan

Ellis

et al. 2018

Joule

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The spatial collection efficiency portrays the driving forces and loss mechanisms in photovoltaic and photoelectrochemical devices. It is defined as the fraction of photogenerated charge carriers created at a specific point within the device that contribute to the photocurrent. In stratified planar structures, the spatial collection efficiency can be extracted out of photocurrent action spectra measurements empirically, with few a priori assumptions. Although this method was applied to photovoltaic cells made of well-understood materials, it has never been used to study unconventional materials such as metal-oxide semiconductors that are often employed in photoelectrochemical cells. This perspective shows the opportunities that this method has to offer for investigating new materials and devices with unknown properties. The relative simplicity of the method, and its applicability to operando performance characterization, makes it an important tool for analysis and design of new photovoltaic and photoelectrochemical materials and devices.

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“…18,19 In addition, electron beam induced current (EBIC), as described in ref. [20][21][22][23], requires fabrication of full device stacks that are measured under vacuum, which prohibits use of this method for characterization of photoelectrochemical systems under real operating conditions. To overcome this characterization gap and extract the diffusion length, Pala et al 24 suggested measuring photocurrent changes in wedge-shaped thin films.…”

Section: Introductionmentioning

confidence: 99%

Quantification of the loss mechanisms in emerging water splitting photoanodes through empirical extraction of the spatial charge collection efficiency

Segev

Jiang

Cooper

et al. 2018

Energy Environ. Sci.

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The operando quantification of surface and bulk losses is key to developing strategies for optimizing photoelectrodes and realizing high efficiency photoelectrochemical solar energy conversion systems. This is particularly true for emerging thin film semiconductors, in which photocarrier diffusion lengths, surface and bulk recombination processes, and charge separation and extraction limitations are poorly understood. Insights into mechanisms of efficiency loss can guide strategies for nanostructuring photoelectrodes, engineering interfaces, and incorporating catalysts. However, few experimental methods are available for direct characterization of dominant loss processes under photoelectrochemical operating conditions. In this work, we provide insight into the function and limitations of an emerging semiconductor photoanode, g-Cu 3 V 2 O 8 , by quantifying the spatial collection efficiency (SCE), which is defined as the fraction of photogenerated charge carriers at each point below the surface that contributes to the measured current. Analyzing SCE profiles at different operating potentials shows that increasing the applied potential primarily acts to reduce surface recombination rather than to increase the thickness of the space charge region under the semiconductor/ electrolyte interface. Comparing SCE profiles obtained with and without a sacrificial reagent allows surface losses from electronically active defect states to be distinguished from performance bottlenecks arising from slow reaction kinetics. Combining these insights promotes a complete understanding of the photoanode performance and its potential as a water splitting photoanode. More generally, application of the SCE extraction method can aid in the discovery and evaluation of new materials for solar water splitting devices by providing mechanistic details underlying photocurrent generation and loss. Broader contextThe next generation of solar energy conversion systems require design and integration of new semiconductor materials. Detailed understanding of the optoelectronic properties of these materials and the driving forces and loss mechanisms that limit device performance is essential to the development of high efficiency systems. Insights into mechanisms of efficiency loss can guide strategies for nanostructuring photoelectrodes, engineering interfaces, and incorporating catalysts. However, few experimental methods are available for direct characterization of dominant loss processes under photoelectrochemical operating conditions. In this work, we provide insight into the function and limitations of an emerging semiconductor photoanode, g-Cu 3 V 2 O 8 , by quantifying the spatial collection efficiency (SCE), which is defined as the fraction of photogenerated charge carriers at every point that contribute to extracted current. Analyzing SCE profiles at different operating potentials while performing different chemical reactions allows distinguishing between bulk and surface losses and between different types of surface recombination mechanisms...

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Doping of polycrystalline CdTe for high-efficiency solar cells on flexible metal foil

Cited by 246 publications

References 32 publications

Structural and electronic properties of CdTe_1-xSe_x films and their application in solar cells

Structural and electronic properties of CdTe_1-xSe_x films and their application in solar cells

The Spatial Collection Efficiency of Charge Carriers in Photovoltaic and Photoelectrochemical Cells

Quantification of the loss mechanisms in emerging water splitting photoanodes through empirical extraction of the spatial charge collection efficiency

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Doping of polycrystalline CdTe for high-efficiency solar cells on flexible metal foil

Cited by 246 publications

References 32 publications

Structural and electronic properties of CdTe1-xSex films and their application in solar cells

Structural and electronic properties of CdTe1-xSex films and their application in solar cells

The Spatial Collection Efficiency of Charge Carriers in Photovoltaic and Photoelectrochemical Cells

Quantification of the loss mechanisms in emerging water splitting photoanodes through empirical extraction of the spatial charge collection efficiency

Contact Info

Product

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Structural and electronic properties of CdTe_1-xSe_x films and their application in solar cells

Structural and electronic properties of CdTe_1-xSe_x films and their application in solar cells