Tailoring MgZnO/CdSeTe Interfaces for Photovoltaics

Ablekim, Tursun; Perkins, Craig L.; Zheng, Xin; Reich, Carey; Swanson, Drew E.; Colegrove, Eric; Duenow, Joel N.; Albin, David S.; Nanayakkara, Sanjini U.; Reese, Matthew O.; Shimpi, Tushar; Sampath, Walajabad S.; Metzger, Wyatt K.

doi:10.1109/jphotov.2018.2877982

Cited by 71 publications

(50 citation statements)

References 24 publications

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“…However, it has been reported that the performance of ZMO/CdTe device degraded gradually while being exposed to ambient conditions, due to the reaction between water in atmosphere and MgO in ZMO films. [19] To further confirm whether the water in the CuSCN solution will degrade the performance of the ZMO/CdTe solar cells during the annealing treatment, a CuSCN solution without water was used for the CuSCN film deposition. Diethyl sulfide has been widely used as the solvent of CuSCN for hole transport layer deposition.…”

Section: Resultsmentioning

confidence: 99%

“…Recently, PCEs of 19.1% and 18.6% for CdSeTe and pure CdTe solar cells, respectively, with ZMO buffer layers have been demonstrated [17]. However, it has also been reported that an oxygen-free atmosphere is required for ZMO/CdTe devices during the CdTe deposition, as well as the post treatments; otherwise, the devices show poor performances, due to the presence of severe S-kinks [18,19]. Additionally, it is reported that the finished ZMO/CdTe devices degrade rapidly when exposing to the ambient atmosphere, likely due to the reaction between water and the ZMO film [20].…”

Section: Introductionmentioning

confidence: 99%

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CuSCN as the Back Contact for Efficient ZMO/CdTe Solar Cells

Song

Bista

et al. 2020

Materials

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The replacement of traditional CdS with zinc magnesium oxide (ZMO) has been demonstrated as being helpful to boost power conversion efficiency of cadmium telluride (CdTe) solar cells to over 18%, due to the reduced interface recombination and parasitic light absorption by the buffer layer. However, due to the atmosphere sensitivity of ZMO film, the post treatments of ZMO/CdTe stacks, including CdCl2 treatment, back contact deposition, etc., which are critical for high-performance CdTe solar cells became crucial challenges. To realize the full potential of the ZMO buffer layer, plenty of investigations need to be accomplished. Here, copper thiocyanate (CuSCN) is demonstrated to be a suitable back-contact material with multi-advantages for ZMO/CdTe solar cells. Particularly, ammonium hydroxide as the solvent for CuSCN deposition shows no detrimental impact on the ZMO layer during the post heat treatment. The post annealing temperature as well as the thickness of CuSCN films are investigated. Finally, a champion power conversion efficiency of 16.7% is achieved with an open-circuit voltage of 0.857 V, a short-circuit current density of 26.2 mA/cm2, and a fill factor of 74.0%.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

CuSCN as the Back Contact for Efficient ZMO/CdTe Solar Cells

Song

Bista

et al. 2020

Materials

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“…The MgZnO/CdTe interface is sensitive to barriers originating from oxides, e.g., MgO, that can be formed during deposition. To obtain high-efficiency MgZnO/CdTe devices, deposition parameters, such as temperature and oxygen partial pressure during deposition, and CdCl 2 treatment, have to be carefully optimized [56].…”

Section: Cdte 1-x Se X /Cdte Devices With a Mgzno Window Layermentioning

confidence: 99%

Review of CdTe1−xSex Thin Films in Solar Cell Applications

2019

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Recent improvements in CdTe thin film solar cells have been achieved by using CdTe1−xSex as a part of the absorber layer. This review summarizes the published literature concerning the material properties of CdTe1−xSex and its application in current thin film CdTe photovoltaics. One of the important properties of CdTe1−xSex is its band gap bowing, which facilitates a lowering of the CdTe band gap towards the optimum band gap for highest theoretical efficiency. In practice, a CdTe1−xSex gradient is introduced to the front of CdTe, which induces a band gap gradient and allows for the fabrication of solar cells with enhanced short-circuit current while maintaining a high open-circuit voltage. In some device structures, the addition of CdTe1−xSex also allows for a reduction in CdS thickness or its complete elimination, reducing parasitic absorption of low wavelength photons.

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“…With such structures at the front of the solar cell, significant improvements were achieved in the short circuit current density ( J SC ) of the device but with little if any improvement in its open circuit voltage ( V OC ) [ 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. Over these last several years, it has been reported that resistive oxide materials can improve the open circuit voltage of the CdTe solar cell by reducing interfacial recombination at the semiconductor n - p junction [ 9 , 10 , 11 ]. In fact, it has been demonstrated that a high-quality junction can be achieved between a high resistivity transparent (HRT) layer and a p -type CdTe absorber layer even without the thin CdS or CdS:O layer, depending on the precise band alignment [ 12 ] and the front barrier height [ 13 ] at the HRT/(absorber layer) interface.…”

Section: Introductionmentioning

confidence: 99%

“…This recent research has shown that ensuring proper energy band alignment at the front of the CdTe solar cell is a critical approach for enhancing V OC of the device. Mg x Zn 1−x O (MZO) has attracted greater attention than other potential HRT layers in such applications due to the flexibility it provides for engineering the interface between the HRT and solar cell layers by tuning the bandgap (E g ) of the MZO through adjustment of the Mg content (x) [10][11][12][13][14][15]. In fact, synthesizing a solid solution of ZnO (E g = 3.3 eV) with wider bandgap MgO (E g = 7.8 eV) is a proven method for engineering wide bandgap semiconductor layers for a variety of applications [16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Optical Properties of Magnesium-Zinc Oxide for Thin Film Photovoltaics

et al. 2021

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Motivated by their utility in CdTe-based thin film photovoltaics (PV) devices, an investigation of thin films of the magnesium-zinc oxide (MgxZn1−xO or MZO) alloy system was undertaken applying spectroscopic ellipsometry (SE). Dominant wurtzite phase MZO thin films with Mg contents in the range 0 ≤ x ≤ 0.42 were deposited on room temperature soda lime glass (SLG) substrates by magnetron co-sputtering of MgO and ZnO targets followed by annealing. The complex dielectric functions ε of these films were determined and parameterized over the photon energy range from 0.73 to 6.5 eV using an analytical model consisting of two critical point (CP) oscillators. The CP parameters in this model are expressed as polynomial functions of the best fitting lowest CP energy or bandgap E0 = Eg, which in turn is a quadratic function of x. As functions of x, both the lowest energy CP broadening and the Urbach parameter show minima for x ~ 0.3, which corresponds to a bandgap of 3.65 eV. As a result, it is concluded that for this composition and bandgap, the MZO exhibits either a minimum concentration of defects in the bulk of the crystallites or a maximum in the grain size, an observation consistent with measured X-ray diffraction line broadenings. The parametric expression for ε developed here is expected to be useful in future mapping and through-the-glass SE analyses of partial and complete PV device structures incorporating MZO.

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Tailoring MgZnO/CdSeTe Interfaces for Photovoltaics

Cited by 71 publications

References 24 publications

CuSCN as the Back Contact for Efficient ZMO/CdTe Solar Cells

CuSCN as the Back Contact for Efficient ZMO/CdTe Solar Cells

Review of CdTe1−xSex Thin Films in Solar Cell Applications

Optical Properties of Magnesium-Zinc Oxide for Thin Film Photovoltaics

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