Research in solar cell technologies at Tallinn University of Technology

Mellikov, E.; Altosaar, M.; Krunks, Malle; Krustok, J.; Varema, T.; Volobujeva, Olga; Kaupmees, L.; Dedova, Tatjana; Timmo, K.; Ernits, K.; Kois, J.; Açik, Ilona Oja; Danilson, Mati; Bereznev, Sergei

doi:10.1016/j.tsf.2007.12.111

Cited by 13 publications

(3 citation statements)

References 31 publications

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“…Although, to date the reaction mechanism of CuInSe 2 formation is still unclear. Mellikov et al (2008) indicated that the mechanism of CuInSe 2 phase formation in one step electrodeposition goes through a number of consecutive reactions and they confirm the coexistence of CuInSe 2 and In 2 Se 3 at more negative deposition potentials. For measurement of the degree of preferential orientation in the films, we defined the variable R I as the ratio of intensity of (1 1 2) peak to the sum of intensities of all peaks in the X-ray pattern (Muller et al 2006).…”

Section: Resultsmentioning

confidence: 64%

One-step electrodeposition process of CuInSe2: Deposition time effect

et al. 2014

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CuInSe 2 thin films were prepared by one-step electrodeposition process using a simplified twoelectrodes system. The films were deposited, during 5, 10, 15 and 20 min, from the deionized water solution consisting of CuCl 2, InCl 3 and SeO 2 onto ITO-coated glass substrates. As-deposited films have been annealed under vacuum at 300 °C during 30 min. The structural, optical band gap and electrical resistivity of elaborated films were studied, respectively, using X-ray diffraction (XRD), Raman spectroscopy, UV spectrophotometer and four-point probe method. The micro structural parameters like lattice constants, crystallite size, dislocation density and strain have been evaluated. The XRD investigation proved that the film deposited at 20 min present CuInSe 2 single phase in its chalcopyrite structure and with preferred orientation along (1 1 2) direction, whereas the films deposited at 5, 10 and 15 min show the CuInSe 2 chalcopyrite structure with the In 2 Se 3 as secondary phase. We have found that the formation mechanism of CuInSe 2 depends on the In 2 Se 3 phase. The optical band gap of the films is found to decrease from 1⋅17 to 1⋅04 eV with increase in deposition time. All films show Raman spectra with a dominant A 1 mode at 174 cm-1 , confirming the chalcopyrite crystalline quality of these films. The films exhibited a range of resistivity varying from 2.3 × 10-3 to 4.4 × 10-1 Ω cm.

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Section: Resultsmentioning

confidence: 64%

One-step electrodeposition process of CuInSe2: Deposition time effect

et al. 2014

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“…The low energy transition is usually attributed to a CZTSe. 19 We will link the RT-PL luminescence peak at around 1.3 eV to a defect luminescence in ZnSe. This PL signal is at higher energy than the calculated 20 and measured 9,21 band gaps of CZTSe.…”

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confidence: 99%

Detecting ZnSe secondary phase in Cu2ZnSnSe4 by room temperature photoluminescence

Djemour

Mousel

Redinger

et al. 2013

Applied Physics Letters

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Secondary phases, such as ZnSe, occur in Cu2ZnSnSe4 and can be detrimental to the resulting solar cell performance. Therefore, it is important to have simple tools to detect them. We introduce subband gap defect excitation room temperature photoluminescence of ZnSe as a practical and non-destructive method to discern the ZnSe secondary phase in the solar cell absorber. The PL is excited by the green emission of an Ar ion laser and is detected in the energy range of 1.2–1.3 eV. A clear spatial correlation with the ZnSe Raman signal confirms this attribution.

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“…At the same time, although several companies and research institutions have made considerable efforts, powder methods for solar cell applications have not found widespread use yet. It has been shown that isothermal recrystallization of initial powders in different molten fluxes appears to be a relatively simple, inexpensive and a convenient method to produce CIS and CZTS powders with an improved crystal structure, that are perquisite for solar cell use [16][17][18][19]. Powders consist of small single crystalline grains.…”

Section: Introductionmentioning

confidence: 99%

Cu ₂ (Zn _x Sn _2‐x )(S _y Se _1‐y ) ₄ Monograin Materials for Photovoltaics

Mellikov

Altosaar

Raudoja

et al. 2010

Ceramic Transactions Series

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In monogram solar cells powders replace wafers or thin films. This allows for cheaper and much more efficient materials production and minimize materials loss. The separation of materials formation from the module fabrication -allowing for all temperatures and purity precautions-is the very important advantage of the monograin layer based technology. Large area module fabrication proceeds without any high temperature steps in a continuous roll-to-roll process. No up-scaling problems arise as is typical of thin-film technologies since a homogenous powder leads to homogenous modules. The influence of different technological parameters to the materials properties was studied and from CZTS=Cu2(Zn x Sn2. x )(S y Sei_ y ) 4 ) monograin powders solar cells have produced with parameters V oc up to 690 mV, fill factors up to 65 % and I sc more than 20 mA/cm . It was founded that changing of the sulfur/selenium ratio allows a change of 1.04 and 1.72 eV the band gap of Cu2(Zn x Sn2-x )(S y Sei. y )4. INTRODUCTIONClimate change and insecurity of power supplies are among the greatest problems for humankind at the moment and solutions are to be found within only a few decades. Large-scale introduction of renewable power systems in combination with a strong increase of power efficiency and saving will be the only way out. For example, in order to stabilize the world's climate a continuous growth of PV by at least about 20 % per year will be needed during the coming decades that will lead to PV installation of at least ten TW P before 2050. To realize these plans new abundant materials and cheap technologies are needed [1],The technologies used today for manufacturing solar cells are the wafer and the thin film technologies [2]. The wafer technology is based on the growth and use of very large monocrystals or the casting of ultrapure silicon or A3B5 materials. This is a very expensive process not only in terms of money but also in terms of energy input. Later these large single or polycrystals with a high degree of chemical purity and physical perfection have to be sawn into wafers which are subjected to sophisticated methods of oxidation, diffusion and chemical treatment in order to form localized regions of different types of conductivity needed for highly efficient solar cell structures. The idea of making crystalline solar cells by growing very large crystals and then cutting them into thin wafers is in fact not the most intelligent way to obtain perfect materials and structures. Thin film technologies of solar cells production can be applied, but the technical parameters of thin film solar cells are as a rule much worse than those of crystalline solar cells. On the other hand, thin film technologies are, in general, much cheaper than monocrystalline materials based technologies, both with respect to financial expenses and energy costs.Although silicon as semiconductor material is still dominating even in the thin film solar cell production, photovoltaic cells based on more complex compound semiconductor materials are becomi...

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Research in solar cell technologies at Tallinn University of Technology

Cited by 13 publications

References 31 publications

One-step electrodeposition process of CuInSe2: Deposition time effect

One-step electrodeposition process of CuInSe2: Deposition time effect

Detecting ZnSe secondary phase in Cu2ZnSnSe4 by room temperature photoluminescence

Cu ₂ (Zn _x Sn _2‐x )(S _y Se _1‐y ) ₄ Monograin Materials for Photovoltaics

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Research in solar cell technologies at Tallinn University of Technology

Cited by 13 publications

References 31 publications

One-step electrodeposition process of CuInSe2: Deposition time effect

One-step electrodeposition process of CuInSe2: Deposition time effect

Detecting ZnSe secondary phase in Cu2ZnSnSe4 by room temperature photoluminescence

Cu 2 (Zn x Sn 2‐x )(S y Se 1‐y ) 4 Monograin Materials for Photovoltaics

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Cu ₂ (Zn _x Sn _2‐x )(S _y Se _1‐y ) ₄ Monograin Materials for Photovoltaics