The formation of ZnTe:Cu and CuxTe double layer back contacts for CdTe solar cells

Kim, Sun Ho; Ahn, Jin Hyung; Kim, Hyung Seok; Lee, Heon Min; Kim, Dong Hwan

doi:10.1016/j.cap.2010.02.037

Cited by 15 publications

(10 citation statements)

References 7 publications

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“…Moreover, the base device shows an efficiency of about 17.46% assuming an ohmic contact with an infinite surface recombination velocity of 1 × 10 7 cm/s ( Figure 5). We chose the simulation data and analysis mostly around a device with a barrier height of 0.3-0.4 eV as this number is more closely related to a realistic CdTe device structure with back Schottky contact [12,[15][16][17][18]31].…”

Section: Experimental Datamentioning

confidence: 99%

“…For the optimization of the device an offset to the CdTe, absorption layer is considered by adding a CdTe layer as an electron-reflector-extended region (ER), (Figure 4). In addition to CdTe, other materials such as CdZnTe, CdMnTe, and CdMgTe may be employed in creating an ER layer [10,14,15,17,29,36]. A thin-layer electron reflector causes the depletion region of the Schottky barrier contact to be narrow where majority of hole carriers can tunnel through minimizing the loss.…”

Section: Electron Reflector Layer Thicknessmentioning

confidence: 99%

“…An important issue related to the limiting performance of the CdTe cells is the back contact. Experimental works show that the CdTe cells at back contact form Schottky barrier thus degrading the cell efficiency and performance [12][13][14][15][16][17][18]. Other limiting factors in performance of CdTe cells are related to the unavailability of the physical material properties which is at incubator status when compared with the mature technology of the silicon and silicon electronics [19][20][21][22][23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%

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Characterization and Modeling of CdS/CdTe Heterojunction Thin-Film Solar Cell for High Efficiency Performance

Fardi

Buny²

2013

International Journal of Photoenergy

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Device simulation is used to investigate the current-voltage efficiency performance in CdTe/CdS photovoltaic solar cell. The role of several limiting factors such as back contact Schottky barrier and its relationship to the doping density and layer thickness is examined. The role of surface recombination velocity at back contact interface and extended CdTe layer is included. The base CdS/CdTe experimental device used in this study shows an efficiency of 16-17%. Simulation analysis is used to optimize the experimental base device under AM1.5 solar spectrum. Results obtained indicate that higher performance efficiency may be achieved by adding and optimizing an extended CdTe electron reflector layer at the back Schottky contact. In the optimization of the CdS/CdTe cell an extended electron reflector region with a barrier height of 0.1 eV and a doping density of 7 × 10 18 cm −3 with an optimum thickness of 100 nm results in best cell efficiency performance of 19.83% compared with the experimental data.

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Section: Experimental Datamentioning

confidence: 99%

Section: Electron Reflector Layer Thicknessmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Characterization and Modeling of CdS/CdTe Heterojunction Thin-Film Solar Cell for High Efficiency Performance

Fardi

Buny²

2013

International Journal of Photoenergy

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“…13) and even less is known about the morphology of this type of films. Although at such high Cu concentration, the possibility of formation of the ternary ZnCuTe alloy was recognized by previous authors [13][14][15] yet the signature of the alloy on the electrical and optical properties has been given relatively little attention. The identification of the alloy is made difficult by the close similarity between the lattice constants of ZnTe and Cu 2 Te in the cubic phase, which makes difficult the identification of the alloy using X-ray diffraction measurements.…”

Section: Introductionmentioning

confidence: 98%

“…[11][12][13] Among the important possible applications of Cu-doped ZnTe is its use as ohmic contact to CdTe in the CdS/CdTe solar cell, which is a potential candidate for wide scale photovoltaic applications. 14,15 All these applications have stimulated a large amount of work on ZnTe:Cu thin films prepared by various techniques including electro-deposition, 16 metalorgnic vapor phase epitaxy, 17 molecular beem epitaxy, 18 vacuum evaporation, 19 and rf sputtering. 15,[20][21][22] Despite the numerous publications on the physical properties of rf sputtered ZnTe:Cu thin films, little is known about the electrical and optical properties of films containing Cu concentration beyond $5 at.…”

Section: Introductionmentioning

confidence: 99%

Morphology, electrical, and optical properties of heavily doped ZnTe:Cu thin films

Akkad

Abdulraheem

2013

Journal of Applied Physics

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We report on a study of the physical properties of ZnTe:Cu films with Cu content up to ∼12 at. % prepared using rf magnetron sputtering. The composition and lateral homogeneities are studied using X-ray photoelectron spectroscopy (XPS). Atomic force microscopy measurements on films deposited at different substrate temperatures (up to 325 °C) yielded activation energy of 12 kJ/mole for the grains growth. The results of XPS and electrical and optical measurements provide evidence for the formation of the ternary zinc copper telluride alloy in films containing Cu concentration above ∼4 at. %. The XPS results suggest that copper is incorporated in the alloy with oxidation state Cu1+ so that the alloy formula can be written Zn1−yCuy Te with y = 2−x, where x is a parameter measuring the stoichiometry in the Cu site. The formation of this alloy causes appreciable shift in the binding energies of the XPS peaks besides an IR shift in the energy band gap. Detailed analysis of the optical absorption data revealed the presence of two additional transitions, besides the band gap one, originating from the Γ8 and Γ7 (spin-orbit) valence bands to a donor level at ∼0.34 eV below the Γ6 conduction band. This interpretation yields a value for the valence band splitting energy Δ ≅ 0.87 eV independent of copper concentration. On the other hand, the mechanism of formation of the alloy is tentatively explained in terms of a point defect reaction in which substitutional Cu defect CuZn is also created. Assuming that substitutional Cu is the dominant acceptor in the Zn rich alloy as in ZnTe, its formation energy was determined to be 1.7 eV close to the theoretical value (1.41 eV) in ZnTe.

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Historical Analysis of High‐Efficiency, Large‐Area Solar Cells: Toward Upscaling of Perovskite Solar Cells

et al. 2020

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1% at 0.4798 cm 2 , and 14.0% at 1.045 cm 2 , respectively, while the corresponding module efficiencies are 25.1% at 866.45 cm 2 , 24.4% at 13 177 cm 2 , 19.2% at 841 cm 2 , 19.0% at 23 573 cm 2 , and 12.3% at 14.322 cm 2 , respectively. [2-4] Silicon modules account for over 90% of the solar cell market share. [5] Although thin-film solar modules compete with silicon solar cells, the efficiency of the former is lower by ≈5 percentage points (%p). [2-4] Recently, a perovskite solar cell was reported, which used an organic metalhalide hybrid material with an ABX 3 perovskite crystal structure as the lightabsorbing layer. [6-8] This type of perovskite solar cell has attracted much attention as a next-generation solar cell. Kojima et al. first reported a perovskite solar cell with an efficiency of 3.8% in 2009. [9] Initially, perovskite solar cells did not receive much attention because of their poor stability and efficiency. However, research has increased since Park and co-workers reported an efficiency exceeding 9% with stability over 500 h in ambient conditions. [10,11] In the last six years, the efficiency of perovskite solar cells increased from 14.1% to 25.2%, which is the thirdhighest single-junction efficiency reported thus far. [2-4] However, perovskite solar cells are facing commercialization issues. For their successful application to the industry, the following problems must first be addressed: [12,13]-Upscaling (high-efficiency, large-area module demonstration)-Stability (performance degradation over times)-Toxicity (lead (Pb) and cesium (Cs) issues). Stability and toxicity problems were introduced relatively early in the literature. [10,11] Immense efforts were devoted to finding the origin of and solution to the degradation of perovskite solar cells. Owing to the dedicated efforts of countless researchers, the degradation factors were identified as the humidity, light, [14,15] heat, [16,17] and electric fields. [12,18] Degradation issues have been addressed with the development of stable perovskite compositions, electron-transfer layers (ETLs) and hole-transfer layers (HTLs), and encapsulations. Several groups have reported perovskite solar cells that passed the International Electrotechnical Commission (IEC) stability test, while Grätzel and co-workers reported a cell that remained stable for one year. [19-22] Thus, stability has been significantly improved. The status and problems of upscaling research on perovskite solar cells, which must be addressed for commercialization efforts to be successful, are investigated. An 804 cm 2 perovskite solar module has been reported with 17.9% efficiency, which is significantly lower than the champion perovskite solar cell efficiency of 25.2% reported for a 0.09 cm 2 aperture area. For the realization of upscaling high-quality perovskite solar cells, the upscaling and development history of conventional silicon, copper indium gallium sulfur/ selenide and CdTe solar cells, which are already commercialized with modules of sizes up to ≈25 000 cm 2 , are reviewed. ...

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The formation of ZnTe:Cu and CuxTe double layer back contacts for CdTe solar cells

Cited by 15 publications

References 7 publications

Characterization and Modeling of CdS/CdTe Heterojunction Thin-Film Solar Cell for High Efficiency Performance

Characterization and Modeling of CdS/CdTe Heterojunction Thin-Film Solar Cell for High Efficiency Performance

Morphology, electrical, and optical properties of heavily doped ZnTe:Cu thin films

Historical Analysis of High‐Efficiency, Large‐Area Solar Cells: Toward Upscaling of Perovskite Solar Cells

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