Characterization of the defect density states in MoOx for c-Si solar cell applications

Scirè, Daniele; Macaluso, Robert; Mosca, Mauro; Mirabella, S.; Gulino, Antonino; Isabella, Olindo; Zeman, Miro; Crupi, I.

doi:10.1016/j.sse.2021.108135

Cited by 4 publications

(3 citation statements)

References 19 publications

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“…For MoS 2 with indirect band gap, n is 2, A and B are set to be 1 × 10 6 cm −1 •eV −1/2 and 5 × 10 6 cm −1 •eV −1/2 . For MoO x , A and B are set to be 3 × 10 5 cm −1 •eV −1/2 and 1 × 10 −12 cm −1 •eV −1/2 to match the experimentally measured absorption coefficient [43].…”

Section: Device Simulation Methodologymentioning

confidence: 99%

Effect of p-MoO_x interfacial layer on the photovoltaic performances of p-MoS₂/n-Si heterojunction solar cells by theoretical simulation

Deng,

Lu,

Xiong

et al. 2023

Phys. Scr.

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As one of particular 2D transition metal dichalcogenide materials, the outstanding properties of MoS2 enable the promising formation of superior homo or heterojunction solar cells. However, in the process of introducing oxygen treatment to modify the interface defects of MoS2/Si solar cells, or modulate the Fermi level of MoS2 films, a thin layer of p-MoOx capping layer is generally produced next to MoS2. In order to essentially clarify the functional mechanism of MoOx layer, p-MoS2/n-Si heterojunction solar cells with or without MoOx interfacial layer are simulated using SCAPS software. The influences of band gap, electron affinity, thickness of MoS2 and front contact barrier height on the performances of p-MoS2/n-Si solar cells are theoretically studied. It is demonstrated that p-MoS2/n-Si solar cell can achieve a high efficiency of 21.9%. With the appearance of MoOx, the effect of location, electron affinity and thickness of MoOx on the photovoltaic performances p-MoS2/n-Si heterojunction solar cells are studied. The efficiencies of p-MoS2/p-MoOx/n-Si solar cells are significantly reduced to be lower than 11.4%, p-MoOx/p-MoS2/n-Si solar cells maintain superior efficiencies over 20% in a large range of electron affinities lower than 3.0 eV for p-MoOx. Consequently, in modulating the Fermi level of MoS2 films through MoOx doping, p-MoOx capping layer is suggested to be located between MoS2 and front electrode rather than at p-MoS2/n-Si interface, to maintain the excellent performances of p-MoS2/n-Si solar cells.

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Section: Device Simulation Methodologymentioning

confidence: 99%

Effect of p-MoO_x interfacial layer on the photovoltaic performances of p-MoS₂/n-Si heterojunction solar cells by theoretical simulation

Deng,

Lu,

Xiong

et al. 2023

Phys. Scr.

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“…where hν is the photon energy, C is a parameter which depends on both the refractive index and the momentum matrix elements and is assumed constant for all the optical transitions [38,66,68], Ni(E) is the density of the initial occupied states, Nf(E) is the density of final empty states, while F(E) is the Fermi-Dirac function. However, since the absorption spectra of the TiOx samples shows a peak in the sub-gap absorption region, the one-electron approximation is not suitable for this analysis and an extension of this model is needed by introducing an additive term modeling the absorption due to the small polarons [40,41], which is a quasiparticle used to model the interaction of trapped electrons with the surrounding atoms [69,70] and is responsible for the peak in the NIR region of the absorption spectrum [71][72][73]; furthermore, the presence of the small polarons has been previously evaluated in TiO2 [74][75][76] and in other TMOs [71,75,77,78]. The small polarons give a contribution to the absorption modeled as a weakly asymmetric Gaussian peak [71,72] with Ap preexponential factor, Ep polaron binding energy and Eop longitudinal-optical phonon energy:…”

Section: Density Of States Extrapolationmentioning

confidence: 99%

“…For this purpose, an absolute photothermal deflection spectroscopy (PDS) setup has been used to measure optical transmittance , reflectance and absorptance values in a wide spectral range [23,24] simultaneously; such technique has been extensively used to achieve information on the defectivity of semiconductors [37][38][39]. Furthermore, the contribution to the absorption coefficient due to the small polaron has also been considered; such technique was previously used for characterizing the sub-gap defect density in transition metal oxides such as molybdenum oxide [40,41].…”

Section: Introductionmentioning

confidence: 99%

Density of states characterization of TiO2 films deposited by pulsed laser deposition for heterojunction solar cells

Scirè¹,

Macaluso²,

Mosca³

et al. 2021

Nano Res.

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The application of titanium dioxide (TiO2) in the photovoltaic field is gaining traction as this material can be deployed in doping -free heterojunction solar cells with the role of electron selective contact. For modeling -based optimization of such contact, knowledge of the titanium oxide defect density of states is crucial. In this paper, we report a method to extract the defect density through n ondestructive optical measures, including the contribution given by small polaron opti cal transitions. The presence of both related to oxygen-vacancy defects and polarons is supported by the results of optical characterizations and the evaluation of previous observations resulting in a defect band fixed at 1 eV below the conduction band edge of the oxide. Solar cells employing pulsed laser deposited-TiO2 electron selective contacts were fabricated and characterized. The J-V curve of these cells showed, however, a S-shape, then a detailed analysis of the reasons of such a behavior was carried out. We use a model involving the series of a standard cell equivalent circuit with a Schottky junction in order to explain these atypical performances. A good matching between the experimental measurements and the adopted theoretical model was obtained. The extracted parameters are listed and analyzed to shade light on the reasons behind the low-performance cells.

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Tunable Hole‐Selective Transport by Solution‐Processed MoO_3−x Via Doping for p‐Type Crystalline Silicon Solar Cells

Wei

Luo

et al. 2023

Solar RRL

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Molybdenum oxide (MoO3−x, x < 3) has been successfully used as an efficient hole‐selective contact material for crystalline silicon heterojunction solar cells. The carrier transport capability strongly depends on its work function, that is, oxygen vacancies; however, there are lack of effective methods to modulate the multiple oxidation states. Herein, the oxidation states of solution‐processed MoO3−x by doping Nb5+ to improve its hole‐selective contact performance with silicon are tuned. With the optimum doping concentration of 5%, both the reduced Mo5+ and oxygen vacancies increase, resulting in a decrease in the contact resistivity between the MoO3−x film and p‐type silicon from 161.1 to 62.9 mΩ·cm2 and an increase of the effective carrier lifetime from 165.4 to 391.0 μs simultaneously. Similarly, the doping of Ta5+ or V5+ in MoO3−x improves the passivated contact performance with silicon, while the former increases the concentration of oxygen vacancies and the latter reduces it. The solar cell with the structure of Ag/MoO3−x:Nb/p‐Si exhibits a conversion efficiency of 18.37%, which is the highest so far reported for the solution‐processed MoO3−x/silicon heterojunction. This work demonstrates a feasible strategy of tuning hole selectivity in MoO3−x by doping for high‐efficiency solar cells and other optoelectronic device applications.

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Characterization of the defect density states in MoOx for c-Si solar cell applications

Cited by 4 publications

References 19 publications

Effect of p-MoO_x interfacial layer on the photovoltaic performances of p-MoS₂/n-Si heterojunction solar cells by theoretical simulation

Effect of p-MoO_x interfacial layer on the photovoltaic performances of p-MoS₂/n-Si heterojunction solar cells by theoretical simulation

Density of states characterization of TiO2 films deposited by pulsed laser deposition for heterojunction solar cells

Tunable Hole‐Selective Transport by Solution‐Processed MoO_3−x Via Doping for p‐Type Crystalline Silicon Solar Cells

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Characterization of the defect density states in MoOx for c-Si solar cell applications

Cited by 4 publications

References 19 publications

Effect of p-MoOx interfacial layer on the photovoltaic performances of p-MoS2/n-Si heterojunction solar cells by theoretical simulation

Effect of p-MoOx interfacial layer on the photovoltaic performances of p-MoS2/n-Si heterojunction solar cells by theoretical simulation

Density of states characterization of TiO2 films deposited by pulsed laser deposition for heterojunction solar cells

Tunable Hole‐Selective Transport by Solution‐Processed MoO3−x Via Doping for p‐Type Crystalline Silicon Solar Cells

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Effect of p-MoO_x interfacial layer on the photovoltaic performances of p-MoS₂/n-Si heterojunction solar cells by theoretical simulation

Effect of p-MoO_x interfacial layer on the photovoltaic performances of p-MoS₂/n-Si heterojunction solar cells by theoretical simulation

Tunable Hole‐Selective Transport by Solution‐Processed MoO_3−x Via Doping for p‐Type Crystalline Silicon Solar Cells