Defect level identification in copper indium selenide (CuInSe2) from photoluminescence studies

Dagan, Geula; Abou‐Elfotouh, F.; Dunlavy, D. J.; Matson, R.; Cahen, David

doi:10.1021/cm00009a019

Cited by 89 publications

(45 citation statements)

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“…Photoluminescence measurements are mostly performed as a function of the position on the sample, i.e., spatially resolved, [2][3][4][5] or as a function of the energy of the emitted photons. 4,[6][7][8][9][10][11][12] Photoluminescence allows deposited films as well as completed solar cells to be characterized in a contactless manner. Bauer et al 6 showed further how to extract the maximum attainable open circuit voltage from absolute photoluminescence measurements.…”

Section: Introductionmentioning

confidence: 99%

Electroluminescence analysis of high efficiency Cu(In,Ga)Se2 solar cells

Kirchartz

Rau

2007

Journal of Applied Physics

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We compare the electroluminescence (EL) of polycrystalline ZnO∕CdS∕Cu(In,Ga)Se2 heterojunction solar cells with similar band gaps but different open circuit voltages, indicating a difference in the electronic quality of the absorber. Temperature dependent EL measurements reveal that all cells feature transitions from donor-acceptor pair recombination at lower temperature to band to band recombination at higher temperatures. However, the less efficient cells show a longer transition range with donor-acceptor pair recombination still apparent at room temperature. We find further that the part of the room temperature spectrum that is due to band to band transitions in the respective cells is relatively broader than expected from a direct semiconductor with a homogeneous band gap. We analyze this spectral broadening by a model that accounts for band gap fluctuations of the absorber material. The experimental results show that the dominant part of this spectral broadening results from the intentional band gap grading and not from stochastic band gap fluctuations. We show further that the spectral EL emission is linked to the photovoltaic external quantum efficiency by electro-optical reciprocity. In a similar way, the external EL quantum efficiency is related to the open circuit voltage of the device. We verify experimentally that the difference between radiative and measured open circuit voltage determines the EL external quantum efficiency of the solar cell. The best Cu(In,Ga)Se2 solar cell reaches an external light emitting diode quantum efficiency of around 0.1%.

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Section: Introductionmentioning

confidence: 99%

Electroluminescence analysis of high efficiency Cu(In,Ga)Se2 solar cells

Kirchartz

Rau

2007

Journal of Applied Physics

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“…A first defect related emission around 0.98-1.00 eV, which is attributed either to a free-bound (FB) or a donor-acceptor (DA) transition (see e.g. [8,4,9,5,10]), a second DA/FB emission around 0.97 eV (see e.g. [8,4,9,5,6,1].…”

Section: Introductionmentioning

confidence: 99%

Do we really need another PL study of CuInSe ₂ ?

Siebentritt¹,

Rega²,

Zajogin³

et al. 2004

phys. stat. sol. (c)

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A detailed composition, intensity and temperature dependent photoluminescence (PL) study of CuInSe 2 has been performed to obtain data on defects, directly comparable to the defects in CuGaSe 2 , prepared under the same conditions. Epitaxial films are grown by metal organic vapour phase epitaxy on GaAs. The PL study reveals three shallow defects, which are responsible for the doping behaviour in CuInSe 2 : two acceptors, 40 and 60 meV deep, and a donor, approximately 12 meV deep. The shallower acceptor dominates for low or no Cu-excess, whereas the deeper one dominates material grown under high Cuexcess. These defects and their compositional dependence are the same as observed in CuGaSe 2 . Thus no fundamental difference concerning the shallow defects exists between these two materials.

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“…This is in reasonable agreement with room temperature values previously assigned to V Se donors (60±80 meV) and O Se acceptors (120±140 meV). [23,24] The model [8] represented by reaction 2 is already quite well established. Therefore, we devote the remainder of this communication to discussing the experimental evidence concerning the effect of sodium on CIS and CIGS films.…”

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confidence: 99%

“…[34] These findings are consistent with the elimination of donor Se vacancies, which both causes a decrease in band bending at grain boundaries and increases the effective p-type doping of the film, as shown in Figure 1 (bottom). In addition, O Se defects act as acceptors, [23,24] further increasing the p-type doping.…”

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confidence: 99%