Band alignment of front contact layers for high-efficiency CdTe solar cells

Kephart, Jason M.; McCamy, James W.; Ma, Zhixun; Ganjoo, Ashtosh; Alamgir, Faisal M.; Sampath, Walajabad S.

doi:10.1016/j.solmat.2016.05.050

Cited by 167 publications

(109 citation statements)

References 35 publications

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“…However, the current record efficiency of 22.3% is still much below the efficiency achievable for CdTe per the Shockley‐Queisser limit for single‐junction solar cells. A recent advance in CdTe solar cells is the replacement of the traditional CdS buffer (emitter) by a wide bandgap metal oxide, such as ZnMgO (ZMO) . This replacement not only avoids the current loss caused by CdS but also introduces a spike to the conduction band offset (CBO) between the buffer and CdTe absorber .…”

Section: Introductionmentioning

confidence: 99%

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: Introductionmentioning

confidence: 99%

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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“…Traditional CdTe contacts were used: a commercially available Pilkington Tec10 soda-lime glass with a SnO 2 :F (FTO) layer followed by a sputtered magnesium zinc oxide (MZO) buffer for the electron contact and an evaporated tellurium layer for the hole contact. [25][26][27] The contacts had been optimized in the past for a CdTe absorber; here no further reoptimization for the alloy absorbers was performed.…”

Section: Methodsmentioning

confidence: 99%

CdCl2 passivation of polycrystalline CdMgTe and CdZnTe absorbers for tandem photovoltaic cells

Swanson

Reich

Abbas

et al. 2018

Journal of Applied Physics

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As single-junction silicon solar cells approach their theoretical limits, tandems provide the primary path to higher efficiencies. CdTe alloys can be tuned with magnesium (CdMgTe) or zinc (CdZnTe) for ideal tandem pairing with silicon. A II-VI/Si tandem holds the greatest promise for inexpensive, high-efficiency top cells that can be quickly deployed in the market using existing polycrystalline CdTe manufacturing lines combined with mature silicon production lines. Currently, all high efficiency polycrystalline CdTe cells require a chloride-based passivation process to passivate grain boundaries and bulk defects. This research examines the rich chemistry and physics that has historically limited performance when extending Cl treatments to polycrystalline 1.7-eV CdMgTe and CdZnTe absorbers. A combination of transmittance, quantum efficiency, photoluminescence, transmission electron microscopy, and energy-dispersive X-ray spectroscopy clearly reveals that during passivation, Mg segregates and out-diffuses, initially at the grain boundaries but eventually throughout the bulk. CdZnTe exhibits similar Zn segregation behavior; however, the onset and progression is localized to the back of the device. After passivation, CdMgTe and CdZnTe can render a layer that is reduced to predominantly CdTe electro-optical behavior. Contact instabilities caused by inter-diffusion between the layers create additional complications. The results outline critical issues and paths for these materials to be successfully implemented in Si-based tandems and other applications.

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“…Solar cell capacitance simulator (SCAPS) is widely used to simulate various types of solar cells including NFA-BHJ [36][37][38][39][40][41][42][43][44]. The calibration of software can be done using control variable method and the experimental work can be reproduced successfully.…”

Section: Introductionmentioning

confidence: 99%

Numerical modelling of non-fullerene organic solar cell with high dielectric constant ITIC-OE acceptor

Nithya

Sudheer

2020

J. Phys. Commun.

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The low dielectric constant of organic semiconductors has been a limiting factor in the organic photovoltaics. Non-Fullerene Acceptor Bulk Heterojunction (NFA-BHJ) organic solar cells with high dielectric constant acceptors have been gaining a lot of attention. No simulation work has been done on NFA-BHJ organic solar cell with a high dielectric constant acceptor so far to study the influence of various material parameters on the device performance. In this work, a comprehensive device modelling of the conventional structure of NFA-BHJ with poly [(2,6-(4,8-(PBDB-T)as the polymer donor and (3,9-bis(2-methylene-(3-(1,1 -dicyanomethylene)-indanone)-5,5,11,11-tetraki(4-hexylphenyl)-dithieno [2,3-d:2,3d]-s-indaceno [1,2-b:5,6-b]dithiophene)) with Oligo-Ethylene side chain (ITIC-OE) as the nonfullerene acceptor is performed. We did a detailed analysis on the impact of technological parameters on the cell performance and optimized the device characteristics to produce improved efficiency. Numerical simulation is done using SCAPS 1-D program and the validity of simulated output has been verified by comparing with the measurements from reported literature. Optimization of the device parameters produced an improved device performance with an open circuit voltage of 0.9562 V , short circuit current density of mA cm −2 , Fill factor of 69.75% and a power conversion efficiency of 11% . The results are encouraging to develop NFA-BHJ organic solar cells with high dielectric constant acceptors in the near future.

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Band alignment of front contact layers for high-efficiency CdTe solar cells

Cited by 167 publications

References 35 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

CdCl2 passivation of polycrystalline CdMgTe and CdZnTe absorbers for tandem photovoltaic cells

Numerical modelling of non-fullerene organic solar cell with high dielectric constant ITIC-OE acceptor

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