pin double-heterojunction thin-film solar cell p-layer assessment

Spies, Jack Alexander; Schäfer, Rolf; Wager, John F.; Hersh, Peter; Platt, Heather A. S.; Keszler, Douglas A.; Schneider, G.; Kykyneshi, Robert; Tate, Janet; Liu, X.; Compaan, A.; Shafarman, William N.

doi:10.1016/j.solmat.2009.01.024

Cited by 38 publications

(22 citation statements)

References 37 publications

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“…Schematic band diagrams of the Mo/MoS 2 /CZTS and Mo/MoSe 2 /CZTSe back junctions proposed based on literature data are depicted in figures 3(a) and (b). Since energy level alignments derived from employing the simple electron affinity rule are in general not reliable [92], both band diagrams have been constructed using the best available estimates for the potential barrier at the Mo/Mo(S, Se) 2 interface and for the valence band offsets (VBO) at the Mo(S, Se) 2 /kesterite interface. Lacking any direct measurements of the energy level alignment at the back contact/kesterite interface, the estimates are derived using the fact that, according to ab initio calculations, E V (CZTSe)−E V (CIGSe)=0.08 eV [93], where E v is the energy of the valence band maximum.…”

Section: Electrical Properties Of the Back Contactmentioning

confidence: 99%

Back and front contacts in kesterite solar cells: state-of-the-art and open questions

et al. 2019

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We review the present state-of-the-art within back and front contacts in kesterite thin film solar cells, as well as the current challenges. At the back contact, molybdenum (Mo) is generally used, and thick Mo(S, Se) 2 films of up to several hundred nanometers are seen in record devices, in particular for selenium-rich kesterite. The electrical properties of Mo(S, Se) 2 can vary strongly depending on orientation and indiffusion of elements from the device stack, and there are indications that the back contact properties are less ideal in the sulfide as compared to the selenide case. However, the electronic interface structure of this contact is generally not well-studied and thus poorly understood, and more measurements are needed for a conclusive statement. Transparent back contacts is a relatively new topic attracting attention as crucial component in bifacial and multijunction solar cells. Front illuminated efficiencies of up to 6% have so far been achieved by adding interlayers that are not always fully transparent. For the front contact, a favorable energy level alignment at the kesterite/CdS interface can be confirmed for kesterite absorbers with an intermediate [S]/([S]+[Se]) composition. This agrees with the fact that kesterite absorbers of this composition reach highest efficiencies when CdS buffer layers are employed, while alternative buffer materials with larger band gap, such as Cd 1−x Zn x S or Zn 1−x Sn x O y , result in higher efficiencies than devices with CdS buffers when sulfurrich kesterite absorbers are used. Etching of the kesterite absorber surface, and annealing in air or inert atmosphere before or after buffer layer deposition, has shown strong impact on device performance. Heterojunction annealing to promote interdiffusion was used for the highest performing sulfide kesterite device and air-annealing was reported important for selenium-rich record solar cells. Cu 2 ZnSnS 4 (CZTS) absorbers for solar cell applications was first reported by Ito and Nakazawa [1]. Early results on CZTS device performance were reported by Friedlmeier et al [2], Seol et al [3], and Katagiri et al [4]. Later a group at IBM reached record performances with power conversion efficiencies (PCEs) above 10% for CZTSSe devices in 2010 [5] and the current record PCE of 12.6% in 2013 [6]. In 2018, researchers from DGIST reached the same performance, 12.6%, but for a larger device area [7]. The device structure used for kesterite solar cells was originally copied from that of Cu(In, Ga)Se 2 , (CIGSe) TFSCs, and is formed by sequential deposition, upon a soda lime glass substrate, of a Mo back contact, the absorber, a CdS buffer layer, and a ZnO/ZnO:Al bi-layer window (i.e. transparent top contact). This structure, schematically shown for CZTSSe in figure 1, is not necessarily ideal for kesterite solar cells, and extensive work has been invested into studies of alternative backand front contacts and related deposition processes. In this paper, the state-of-the-art and current open questions related to the back and front c...

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Section: Electrical Properties Of the Back Contactmentioning

confidence: 99%

Back and front contacts in kesterite solar cells: state-of-the-art and open questions

et al. 2019

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“…6 These materials have potential applications in different technological fields such as transparent electronics, 7 thermoelectrics, 8 optoelectronics, 9 and photovoltaics. 10 In this paper, we present a detailed experimental and theoretical study of the electronic and optical properties of one family in this group, Ba-based chalcogenide-fluorides BaCuChF ͑Ch =S,Se,Te͒ and their solid solutions, which show p-type conductivity, wide direct optical band gaps, and room temperature excitons. The structural anisotropy of BaCuChF gives rise to anisotropic effective masses of electrons and holes, and to large exciton reduced masses ͑0.90m e and 0.80m e in BaCuSF and BaCuSeF respectively, compared to 0.058m e in GaAs͒, which lead to large exciton binding energies ͑95 meV and 65 meV, compared to 4.2 meV in GaAs͒.…”

Section: Introductionmentioning

confidence: 99%

Electronic structure and excitonic absorption inBaCuChF(Ch=S, Se, and Te)

et al. 2010

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Double excitonic absorption peaks are observed in textured BaCuSF and BaCuSeF thin films. The excitonic doublet separation increases with increasing fraction of heavy chalcogen in the thin-film solid solutions, in good agreement with the spin-orbit splitting of the valence bands calculated by density-functional theory. In BaCuSF and BaCuSeF, the excitons have large binding energies ͑95 and 65 meV, respectively͒ and can be observed at room temperature. A three-dimensional Wannier-Mott excitonic absorption model gives good agreement between the experimental and theoretical optical properties. Band gaps of BaCuSF and BaCuSeF calculated using the GW approximation agree with experiment. In BaCuTeF, transitions across the lowest direct energy gap and excitonic absorption are suppressed, extending its transparent range.

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“…These nanotubes and nanowires can be used in pore filling due to their open porous structures. Moreover, they are reported to be better in electron transportation and recombination behavior and hole conductors presenting faster recombination than nanoparticulate films in liquidbased DSSCs [73][74][75].…”

Section: Photoanodesmentioning

confidence: 99%

Perovskite as Light Harvester: Prospects, Efficiency, Pitfalls and Roadmap

Srivastava¹

2017

Nanostructured Solar Cells

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In the recent years, perovskite materials have attracted great attention due to their excellent light-harvesting properties. The organic materials of these hybrid inorganic organic light harvesters are used as sensitizers and the inorganic materials have been used as light absorbers. The exceptional properties of these materials such as long diffusion length, high carrier mobility, affordable device fabrication, and adjustable adsorption range have created a new era in optoelectronic technologies. The perovskites have become promising materials due of their versatility in device architecture, flexibility in material growth, and ability to achieve the high efficiency through various processing techniques. The superior performance of silicon-based tandems by achieving efficiency more than 40% has encouraged researchers to further expand the investigations to higher levels. The quest to transit the research curiosity to the market photovoltaic technology has given a new dimension to the remarkable ascension of perovskite solar cells. This chapter introduces the experimental and theoretical aspects, the electrical and optical properties, pitfalls, and a roadmap for the future prospects of perovskite materials.

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pin double-heterojunction thin-film solar cell p-layer assessment

Cited by 38 publications

References 37 publications

Back and front contacts in kesterite solar cells: state-of-the-art and open questions

Back and front contacts in kesterite solar cells: state-of-the-art and open questions

Electronic structure and excitonic absorption inBaCuChF(Ch=S, Se, and Te)

Perovskite as Light Harvester: Prospects, Efficiency, Pitfalls and Roadmap

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