The Effects of Hydrogen Iodide Back Surface Treatment on CdTe Solar Cells

Awni, Rasha A.; Li, Deng Bing; Grice, Corey R.; Song, Zhaoning; Razooqi, Mohammed A.; Phillips, Adam B.; Bista, Sandip S.; Roland, Paul J.; Alfadhili, Fadhil K.; Ellingson, Randy J.; Heben, Michael J.; Li, Jian V.; Yan, Yanfa

doi:10.1002/solr.201800304

Cited by 32 publications

(30 citation statements)

References 41 publications

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“…The extracted back barrier heights are in good agreement with those obtained from J‐V‐T curves (Figure S3). Similar values were found previously in CdTe devices with back surface treatment.…”

Section: Resultssupporting

confidence: 91%

“…From the Arrhenius plots illustrated in Figure 2A Figure S3). Similar values were found previously 17,20 in CdTe devices with back surface treatment.…”

Section: Front and Back Interface Barrierssupporting

confidence: 91%

“…18,19 This model is illustrated by the subcircuits colored in black in Figure 1B. In previous modeling, 17 no front barrier at CdS/CdTe interface has been considered due to their cliff CBO. However, replacing CdS by ZMO could introduce a spike CBO.…”

Section: Equivalent Circuit Modelmentioning

confidence: 99%

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Influences of buffer material and fabrication atmosphere on the electrical properties of CdTe solar cells

Awni

Song

et al. 2019

Progress in Photovoltaics

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The electrical properties such as interface energy barriers, defect energy levels, and densities dictate the performance of thin film solar cells. Here, we show that these properties can be quantified in cadmium telluride (CdTe) thin‐film solar cells using admittance spectroscopy‐based techniques. Our results reveal that the electrical properties in CdTe thin‐film solar cells depend on both buffer material and the fabrication atmosphere. We find that only a negligible front contact barrier exists at the CdS/CdTe front junction regardless of the fabrication atmospheres, while an obvious front barriers are observed at the ZnMgO (ZMO)/CdTe junctions. Both CdS/CdTe and ZMO/CdTe solar cells exhibit back contact barrier. The energy level of defects is shallower in CdS/CdTe cells than in ZMO/CdTe cells. The fabrication atmosphere influences the electrical properties, i.e., an oxygen‐free atmosphere reduces the front and back barrier heights and lowers the energy level of defects. The results provide critical insights for understanding and optimizing the performance of CdTe thin‐film solar cells.

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Section: Resultssupporting

confidence: 91%

“…From the Arrhenius plots illustrated in Figure 2A Figure S3). Similar values were found previously 17,20 in CdTe devices with back surface treatment.…”

Section: Front and Back Interface Barrierssupporting

confidence: 91%

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Influences of buffer material and fabrication atmosphere on the electrical properties of CdTe solar cells

Awni

Song

et al. 2019

Progress in Photovoltaics

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“…It is well established in other technologies that surface modification prior to back contacting can lead to performance improvement, such as via the nitric-phosphoric acid, [15][16][17][18] bromine methanol [19], methyl ammonium iodide [20] or hydrogen iodide [21] etching step in CdTe solar cells. These etching steps often improve device characteristics through the creation of a Te-rich layer prior to back contacting.…”

Section: Introductionmentioning

confidence: 99%

Chemical etching of Sb₂Se₃ solar cells: surface chemistry and back contact behaviour

et al. 2019

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The effect of (NH 4 ) 2 S and CS 2 chemical etches on surface chemistry and contacting in Sb 2 Se 3 solar cells was investigated via a combination of x-ray photoemission spectroscopy (XPS) and photovoltaic device analysis. Thin film solar cells were produced in superstrate configuration with an absorber layer deposited by close space sublimation. Devices of up to 5.7% efficiency were compared via currentvoltage measurements (J-V ) and temperature-dependent current-voltage (J-V-T) analysis. XPS analysis demonstrated that both etching processes were successful in removing Sb 2 O 3 contamination, while there was no decrease in free elemental selenium content by either etch, in contrast to prior work. Using J-V-T analysis the removal of Sb 2 O 3 at the back surface in etched samples was found to improve contacting by reducing the potential barrier at the back contact from 0.43 eV to 0.26 eV and lowering the series resistance. However, J-V data showed that due to the decrease in shunt resistance and short-circuit current as a result of etching, the devices show a lower efficiency following both etches, despite a lowering of the series resistance. Further optimisation of the etching process yielded an improved efficiency of 6.6%. This work elucidates the role of surface treatments in Sb 2 Se 3 devices and resolves inconsistencies in previously published works.

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“…Till now, there are only few reports on the optimization of post treatments, especially the back-contact treatment for ZMO/CdTe solar cells. During the optimization processes, we have tried different hole transport materials (e.g., metallic Cu [21], carbon paste [22]) and back surface treatments (e.g., hydroiodic (HI) solution [23], Br methanol solution [24] and MAI solution [25] etching), which have been demonstrated effective in improving the CdS/CdTe device performance. However, most of these processes show adverse effects on the ZMO/CdTe devices, probably caused by the degradation of the ZMO films during the depositions or treatments.…”

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 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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The Effects of Hydrogen Iodide Back Surface Treatment on CdTe Solar Cells

Cited by 32 publications

References 41 publications

Influences of buffer material and fabrication atmosphere on the electrical properties of CdTe solar cells

Influences of buffer material and fabrication atmosphere on the electrical properties of CdTe solar cells

Chemical etching of Sb₂Se₃ solar cells: surface chemistry and back contact behaviour

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

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The Effects of Hydrogen Iodide Back Surface Treatment on CdTe Solar Cells

Cited by 32 publications

References 41 publications

Influences of buffer material and fabrication atmosphere on the electrical properties of CdTe solar cells

Influences of buffer material and fabrication atmosphere on the electrical properties of CdTe solar cells

Chemical etching of Sb2Se3 solar cells: surface chemistry and back contact behaviour

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

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Product

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Chemical etching of Sb₂Se₃ solar cells: surface chemistry and back contact behaviour