Thin-film intermediate band chalcopyrite solar cells (original) (raw)
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Journal of Applied Physics, 2008
This paper discusses the potential of the intermediate band solar cell ͑IBSC͒ concept to improve the efficiency of thin-film chalcopyrite solar cells. The results show that solar cells based on CuGaS 2 , with a radiative limiting efficiency of 46.7%, exhibit the highest potential. A simple method for the identification of transition elements that when incorporated in CuGaS 2 could possibly introduce an intermediate band is also described. The IBSC concept is also applied under the assumptions that thin-film solar cells are not to be operated under concentrated light and that a non-negligible contribution of nonradiative recombination exists.
Solar Energy Materials and Solar Cells, 2010
Chalcopyrite Nanostructures Solar cells Nanostructured chalcopyrite compounds have recently been proposed as absorber materials for advanced photovoltaic devices. We have used photoreñectance (PR) to evalúate the impact of interdiffusion phenomena and the presence of native defects on the optoelectronic properties of such materials. Two model material systems have been analyzed: (i) thin layers of CuGaSe 2 (£ g =1.7 eV) and CuInSe 2 (1.0 eV) in a wide/low/wide bandgap stack that have been grown onto GaAs(0 0 1) substrates by metalorganic chemical vapor deposition (MOCVD); and (ii) thin In 2 S 3 samples (£ g =2.0 eV) containing small amounts of Cu that have been grown by co-evaporation (PVD) intending to form Cu x In y S z (£ g~1 .5 eV) nanoclusters into the In 2 S 3 matrix. The results have been analyzed according to the third-derivative functional form (TDFF). The valence band structure of selenide reference samples could be resolved and uneven interdiffusion of Ga and In in the layer stack could be inferred from the shift of PR-signatures. Hints of electronic confinement associated to the transitions at the low-gap región have been found in the selenide layer stack. Regarding the sulphide system, In 2 S 3 is characterized by the presence of native deep states, as revealed by PR. The defect structure of the compound undergoes changes when incorporating Cu and no conclusive result about the presence of ternary clusters of a distinct phase could be drawn. Interdiffusion phenomena and the presence of native defects in chalcopyrites and related compounds will determine their potential use in advanced photovoltaic devices based on nanostructures. (D. Fuertes Marrón). energy range of zero density of states, as originally proposed by Luque and Martí . The device is completed with two emitters that selectively extract electrons and holes at either side of the absorber. In this way, three absorption onsets are expected at photon energies corresponding to transitions from the valence band to the intermedíate band, from the intermedíate to the conduction band, and from the valence to the conduction band, leading to an increase of the generated photocurrent. The proper use of the emitters and the isolation of the intermedíate band material from the contacts ensure that the expected voltage delivered by the device will be limited by the main gap of the material and not by any of the sub-bandgaps associated to the intermedíate band. The overall balance is an increased efficiency of energy conversión .
Thin Solid Films, 2007
Electronic structure calculations are carried out for CuGaS 2 partially substituted with Ti, V, Cr or Mn to ascertain if some of these systems could provide an intermediate band material able to give a high efficiency photovoltaic cell. Trends in electronic level positions are analyzed and more accurate advanced theory levels (exact exchange or Hubbard-type methods) are used in some cases. The Ti-substituted system seems more likely to yield an intermediate band material with the desired properties, and furthermore seems realizable from the thermodynamic point of view, while those with Cr and Mn might give half-metal structures with applications in spintronics.
A Deep Outlook for the Chalcopyrite Solar Cells: For Future Perspectives
International Journal of Energy and Power Engineering
This publication investigates to present all new scientific and industrial works all rolled into one with more effective and predictability aspect in chalcopyrite Photovoltaics (PVs). The paper suggests that comprehensive and fine-tuned directions supporting a large portfolio of solar energy materials could be extended to most efficiency, which mostly depend on the growth techniques especially usage rates in substituents and their characteristic/specific properties. There is an indispensable source of solar energy. If this were the case, new energy materials could well become a competitive alternative in many applications within the next few years. This publication builds upon past analyses of chalcopyrites contained in the word Energy outlook as efficient alternative materials. It aims at offering an updated picture of current technology trends/demands/markets, as well as new analyses on how solar energy technologies/materials for capturing the purposed efficiency and durableness can be used in the various energy consuming/developing sectors, now and in the future. In this work we have tried to summarize the all significant studies about Chalcopyrite solar cells from the past to the present and also tried to introduce Te doped CuInGaSeTe compound which is a new member of the family that we produced.
Electronic and chemical properties of non-vacuum deposited chalcopyrite solar cells
Photovoltaic Specialists, IEEE Conference, 2011
We have investigated the electronic and chemical surface properties of a Cu(In1−xGax)Se2 (CIGSe) thin-film solar cell absorber and a CdS/CIGSe interface sample taken from Nanosolar's manufacturing line. Using soft x-ray and UV photoelectron spectroscopy, inverse photoemission, and soft x-ray emission spectroscopy employing high-brilliance synchrotron radiation, we have determined the chemical composition of the surface and near-surface bulk, as well as
Preparation and characterization of chalcopyrite compound for thin film solar cells
Alexandria Engineering Journal, 2011
CulnS 2 thin films were electrodeposited onto indium tin oxide substrate by the electrodeposition technique. Cyclic voltammetry and chronoamperometry were carried out to determine the optimum pH and the amount of sodium thiosulfate for electroplating CuInS 2 compound. The composition, crystallinity and optical properties of the compounds synthesized were studied by energy dispersive X-ray (EDX), (SEM), X-ray diffraction and UV-Visible spectra. It was found that the increasing pH shifts the electrodepositions voltage toward more negative and lowers the deposition current. Increasing the amount of sodium thiosulfate also decreases the deposition current but it has no effect on the deposition potential. It was concluded that CuInS 2 with atomic stoichiometric ratio was prepared at pH equals 1 and 150 ml of 0.1 M sodium thiosulfate, 5 ml of 0.1 M indium chloride and 5 ml of 0.1 M cupper acetate. The energy gaps were calculated to be 1.6, 1.7 and 1.75 eV for CuInS 2 prepared at 1, 1.5 and 2 of pH, respectively. It was indicated that the amount of the sodium thiosulfate has a slight effect on the energy gap.
Thin film tandem photovoltaic cell from II-IV-V chalcopyrites
Applied Physics Letters, 2010
Using quasiparticle self-consistent GW ͑QSGW͒ theory, we analyze materials properties of the II-IV-V family of chalcopyrite semiconductors consisting of compounds and alloys based on ͑Mg, Zn, Cd͒͑Si, Ge, Sn͒͑P,As͒ 2 , and show how they may offer excellent opportunities for the development of tandem thin-film solar cells. The constituent elements are abundant and nearly lattice-matched compounds can be found with near optimum band gaps. We show the close connection to band structures of other fourfold coordinated compounds that have led to the highest efficiency devices, and suggest potentially optimum alloys for tandem thin-film cells.
Chalcopyrite thin film solar cells by electrodeposition
Solar Energy, 2004
This paper reviews the state of the art in using electrodeposition to prepare chalcopyrite absorber layers in thin film solar cells. Most of the studies deal with the direct preparation of Cu(In,Ga)Se 2 films, and show that the introduction of gallium in the films is now becoming possible from single bath containing all the elements. Electrodeposition can also be used to form precursor films with stacked layer structures, of pure elements or of combinations with binary or even ternary films. Thermal annealing treatments are of dramatic importance to provide suitable electronic quality to the layers. They are often done in the presence of a chalcogen (selenium or sulfur) over pressure and there is a tendency to use rapid thermal processes. Less studies are devoted to complete solar cell formation. Significant progresses have been made in the recent period with several groups achieving cell efficiencies around 8-10% on different substrates. A record efficiency of 11.3% is reported for a cell with an absorber presenting a band gap of 1.47 eV. First results on the manufacturability of the corresponding process to large areas are presented.
Thin Solid Films, 2008
The optical properties of a novel potential high-efficiency photovoltaic material have been studied. This material is based on a chalcopyritetype semiconductor (CuGaSa) with some Ga atom substituted by Ti and is characterized by the formation of an isolated transition-metal band between the valence band and the conduction band. We present a study in which ab-initio density functional theory calculations within the generalized gradient approximation are carried out to determine the optical reflectivity and absorption coefficient of the materials of interest. Calculations for the host semiconductor are in good agreement with experimental results within the limitations of the approach. We find, as desired, that because of the intermediate band, the new Ti-substituted material would be able to absorb photons of energy lower than the band-gap of the host chalcopyrite. We also analyze the partial contributions to the main peaks of its spectrum.