Robust passivation of CdSeTe based solar cells using reactively sputtered magnesium zinc oxide

Yeung, Gavin; Reich, Carey; Onno, Arthur; Bothwell, Alexandra; Danielson, Adam; Holman, Zachary C.; Sampath, Walajabad S.; Wolden, Colin A.

doi:10.1016/j.solmat.2021.111388

Cited by 14 publications

(8 citation statements)

References 43 publications

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“…On the other hand, all target cells show a clear improvement in V OC s, FFs, and, therefore, PCEs. The V OC (0.863 V) of the champion device is as high as that reported for the champion Cd(Se,Te) solar cell using ZMO buffer layer 12 , 36 , 46 . It is noted that the target solar cells show significantly increased reproducibility as compared with Cd(Se,Te) solar cells using ZMO buffer layers (Supplementary Fig.…”

Section: Resultssupporting

confidence: 46%

20%-efficient polycrystalline Cd(Se,Te) thin-film solar cells with compositional gradient near the front junction

Bista

Awni

et al. 2022

Nat Commun

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Bandgap gradient is a proven approach for improving the open-circuit voltages (VOCs) in Cu(In,Ga)Se2 and Cu(Zn,Sn)Se2 thin-film solar cells, but has not been realized in Cd(Se,Te) thin-film solar cells, a leading thin-film solar cell technology in the photovoltaic market. Here, we demonstrate the realization of a bandgap gradient in Cd(Se,Te) thin-film solar cells by introducing a Cd(O,S,Se,Te) region with the same crystal structure of the absorber near the front junction. The formation of such a region is enabled by incorporating oxygenated CdS and CdSe layers. We show that the introduction of the bandgap gradient reduces the hole density in the front junction region and introduces a small spike in the band alignment between this and the absorber regions, effectively suppressing the nonradiative recombination therein and leading to improved VOCs in Cd(Se,Te) solar cells using commercial SnO2 buffers. A champion device achieves an efficiency of 20.03% with a VOC of 0.863 V.

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Section: Resultssupporting

confidence: 46%

20%-efficient polycrystalline Cd(Se,Te) thin-film solar cells with compositional gradient near the front junction

Bista

Awni

et al. 2022

Nat Commun

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“…Namely, when MgZnO is deposited via reactive sputtering using Mg and Zn targets in a high-oxygen ambient, MgZnO was found to be stable to device processing. [36,89] When the MgZnO was sputtered from hot pressed mixed powder (MgO and ZnO) targets in a low-oxygen ambient, however, Mg concentration, and therefore MgZnO bandgap, was found to decrease after processing and/or annealing. [88] In addition, there was evidence for CdSe x Te 1Àx oxidation from the MgZnO, which was not observed in MgZnO/CdTe devices.…”

Section: Science Of Buried Interfaces In Cdtementioning

confidence: 99%

“…In the case of MgZnO/CdSe x Te 1− x devices, no interdiffusion of the MgZnO and CdSe x Te 1− x has been observed, [ 88,89 ] but the MgZnO deposition conditions do appear to affect its stability. Namely, when MgZnO is deposited via reactive sputtering using Mg and Zn targets in a high‐oxygen ambient, MgZnO was found to be stable to device processing.…”

Section: Science Of Buried Interfaces In Cdtementioning

confidence: 99%

Thermomechanical Cleave of Polycrystalline CdTe Solar Cells and its Applications: A Review

2023

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One of the primary research challenges for cadmium telluride (CdTe) solar cells is addressing its open‐circuit voltage (VOC) deficit. While theoretical studies and single crystal work show VOC > 1 V is possible, devices remain stubbornly low at ≈800–900 mV. As absorber opto‐electronic properties (e.g., hole density, carrier lifetime) are improved, device modeling suggests that interfaces become limiting. Because CdTe‐based devices are typically grown in the superstrate configuration, the back interface is relatively accessible for manipulation and study, while the front interface (i.e., the heterojunction region) is buried under microns of material and inaccessible. NREL has developed a novel technique to thermomechanically cleave polycrystalline CdTe device stacks directly at the front interface, enabling characterization and controlled manipulation of this important region. Herein, recent work, primarily from NREL, will be reviewed, including considerations for achieving successful delamination; key scientific discoveries about the front interface that have been enabled by this technique; and practical applications, such as flexible, low‐cost solar with high power‐to‐weight ratio.

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“…Recent modeling has shown that band and Fermi level alignment between the front interface emitter and the absorber is necessary for low front interfacial recombination currents and high efficiency. , When the conduction band and Fermi level of the emitter are relatively high in energy as compared to those of the absorber, the conduction band offset (CBO) is assigned to be positive and the band bending that drives the majority carrier holes away from the front interface is increased in the absorber. To date, only one buffer material system, consisting of combinations of MgO and ZnO (i.e., Mg x Zn 1– x O), has been communicated in the literature with the ability to tune the CBO and reduce front interface recombination to achieve efficiencies as high as 19.5% …”

mentioning

confidence: 99%

“…To date, only one buffer material system, consisting of combinations of MgO and ZnO (i.e., Mg x Zn 1−x O), has been communicated in the literature with the ability to tune the CBO and reduce front interface recombination to achieve efficiencies as high as 19.5%. 13 A recent modeling paper by Dive et al suggested that the materials in the In 2 O 3 −Ga 2 O 3 system could possibly be a second potential candidate materials system for CdTe emitter fabrication. 14 Although the component oxides, In 2 O 3 and Ga 2 O 3 , have bandgaps between 2.9 and 3.6 eV 15−18 Here, we present an experimental examination of IGO materials for use as emitters in CdTe-based solar cells.…”

mentioning

confidence: 99%

Indium Gallium Oxide Emitters for High-Efficiency CdTe-Based Solar Cells

Jamarkattel

Phillips

Subedi

et al. 2022

ACS Appl. Energy Mater.

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There are limited choices for front-surface, electron-selective contacts (emitters) for CdTe solar cells, thus hindering scientific and technical development. Here we investigate the photovoltaic performance of devices fabricated with (In x Ga 1−x ) 2 O 3 (IGO) emitters with varying In-to-Ga ratios prepared by cosputtering. In agreement with predictions, an IGO emitter with a 4.03 eV bandgap (x = 0.36) allowed fabrication of devices with efficiencies of 16%. Increasing the performance to higher values will be enabled by increasing the transmission through the IGO-coated substrate and decreasing the bulk and back interface recombination. These findings demonstrate IGO materials as effective emitters in highefficiency CdTe-based solar cells.

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Robust passivation of CdSeTe based solar cells using reactively sputtered magnesium zinc oxide

Cited by 14 publications

References 43 publications

20%-efficient polycrystalline Cd(Se,Te) thin-film solar cells with compositional gradient near the front junction

20%-efficient polycrystalline Cd(Se,Te) thin-film solar cells with compositional gradient near the front junction

Thermomechanical Cleave of Polycrystalline CdTe Solar Cells and its Applications: A Review

Indium Gallium Oxide Emitters for High-Efficiency CdTe-Based Solar Cells

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