On the assessment of CIGS surface passivation by photoluminescence

Joel, Jonathan; Vermang, Bart; Larsen, Jes K.; Donzel‐Gargand, Olivier; Edoff, Marika

doi:10.1002/pssr.201510081

Cited by 19 publications

(15 citation statements)

References 7 publications

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“…Broad emission is typical of Cu-poor CIGS polycrystalline solar cells, [59][60][61] however, for the case of the reference solar cell, the luminescence is significantly broader than that of the passivated cell. [64][65][66][67][68] However, a direct comparison of PL intensity from different samples should be done with caution due to the necessarily different optical alignments despite nominally equivalent experimental conditions and as in this work we do not have those capabilities and we do not perform that comparison here. [62,63] Regarding the passivated solar cell, the full width at half maximum (FWHM) is significantly lower (≈61 meV) than that of the reference solar cell (≈96 meV).…”

Section: Photoluminescencementioning

confidence: 99%

“…In the literature, in addition to the shape of the PL emission at low temperature, to infer the effect of the passivation layer, quite often a comparison of the PL intensity is performed. [64][65][66][67][68] However, a direct comparison of PL intensity from different samples should be done with caution due to the necessarily different optical alignments despite nominally equivalent experimental conditions and as in this work we do not have those capabilities and we do not perform that comparison here. With the used excitation wavelength, 514.5 nm, penetration depth of the incident photons, ≈70 nm, is smaller than the CIGS thickness, 350 nm.…”

Section: Photoluminescencementioning

confidence: 99%

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Passivation of Interfaces in Thin Film Solar Cells: Understanding the Effects of a Nanostructured Rear Point Contact Layer

Salomé

Vermang

Ribeiro‐Andrade

et al. 2017

Adv Materials Inter

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110

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Thin film solar cells based in Cu(In,Ga)Se2 (CIGS) are among the most efficient polycrystalline solar cells, surpassing CdTe and even polycrystalline silicon solar cells. For further developments, the CIGS technology has to start incorporating different solar cell architectures and strategies that allow for very low interface recombination. In this work, ultrathin 350 nm CIGS solar cells with a rear interface passivation strategy are studied and characterized. The rear passivation is achieved using an Al2O3 nanopatterned point structure. Using the cell results, photoluminescence measurements, and detailed optical simulations based on the experimental results, it is shown that by including the nanopatterned point contact structure, the interface defect concentration lowers, which ultimately leads to an increase of solar cell electrical performance mostly by increase of the open circuit voltage. Gains to the short circuit current are distributed between an increased rear optical reflection and also due to electrical effects. The approach of mixing several techniques allows us to make a discussion considering the different passivation gains, which has not been done in detail in previous works. A solar cell with a nanopatterned rear contact and a 350 nm thick CIGS absorber provides an average power conversion efficiency close to 10%.

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Section: Photoluminescencementioning

confidence: 99%

Section: Photoluminescencementioning

confidence: 99%

Passivation of Interfaces in Thin Film Solar Cells: Understanding the Effects of a Nanostructured Rear Point Contact Layer

Salomé

Vermang

Ribeiro‐Andrade

et al. 2017

Adv Materials Inter

Self Cite

110

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show abstract

“…7 by means of photoluminescence (PL) measurements, where an elevated PL intensity by one order of magnitude was seen for passivated CIGS absorbers compared to unpassivated absorbers (i.e. no Al2O3 passivation layer) [30]. Such an improvement in cell performance can be attributed to (i) reduced recombination at the CIGS/Mo-back contact (i.e.…”

Section: Introductionmentioning

confidence: 99%

Addressing the impact of rear surface passivation mechanisms on ultra-thin Cu(In,Ga)Se2 solar cell performances using SCAPS 1-D model

Kotipalli

Poncelet

et al. 2017

Solar Energy

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We present a (1-D) SCAPS device model to address the following: (i) the surface passivation mechanisms (i.e. field-effect and chemical), (ii) their impact on the CIGS solar cell performance for varying CIGS absorber thickness, (iii) the importance of fixed charge type (+/-) and densities of fixed and interface trap charges, and (iv) the reasons for discrete gains in the experimental cell efficiencies (previously reported) for varying CIGS absorber thickness. First, to obtain a reliable device model, the proposed set of parameters is validated for both field-effect (due to fixed charges) and chemical passivation (due to interface traps) using a simple M-IS test structure and experimentally extracted values (previously reported) into the SCAPS simulator. Next, we provide figures of merits without any significant loss in the solar cell performances for minimum net-Qf and maximum acceptable limit for Dit, found to be ~5x10 12 cm-2 and ~1x10 13 cm-2 eV-1 respectively. We next show that the influence of negative fixed charges in the rear passivation layer (i.e. field-effect passivation) is more predominant than that of the positive fixed charges (i.e. counter-field effect) especially while considering ultra-thin (< 0.5 μm) absorber layers. Furthermore, we show the importance of rear reflectance on the short-circuit photocurrent densities while scaling down the CIGS absorber layers below 0.5 μm under interface chemical and field-effect passivation mechanisms. Finally, we provide the optimal rear passivation layer parameters for efficiencies greater than 20% with ultra-thin CIGS absorber thickness (< 0.5 μm). Based on these simulation results, we confirm that a negatively charged rear surface passivation with nano-point contact approach is efficient for the enhancement of cell performances, especially while scaling down the absorber thickness below 0.5 μm.

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“…Various research groups have shown that Al2O3 is very suitable to passivate the rear of Cu(In,Ga)Se2 (CIGS) thin film solar cells, which can be explained by a combination of chemical and field effect passivation. Opto-electrical measurements can be used to screen interesting passivation layers, as is shown for Al2O3 grown on CIGS [3]. Even more, electrical measurements of similar structures show that the Al2O3 layers exhibit a high density of negative fixed charges (its field effect passivation) in combination with a reasonably low interface trap density (its chemical passivation) [4].…”

Section: Rear Surface Passivation Schemes For Cigsmentioning

confidence: 99%