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Title: Heterojunction solar cell with 2% efficiency based on a Cu{sub 2}O substrate

Abstract

We report on the fabrication of heterojunction solar cells made by deposition of transparent conducting oxide (TCO) films on Cu{sub 2}O substrates. The TCO films have been grown by ion beam sputtering on good quality Cu{sub 2}O sheets prepared by oxidizing copper at a high temperature. The best solar cell has reached an open-circuit voltage of 0.595 V, a short-circuit current density of 6.78 mA/cm{sup 2}, a fill factor of 50%, and a conversion efficiency of 2% under simulated AM1.5G illumination, which is the highest efficiency value reported for this kind of heterojunction devices. These devices represent a good starting point for the development of very low cost solar cells.

Authors:
; ; ; ;  [1]
  1. Casaccia Research Center, ENEA, via Anguillarese 301, 00060, Rome (Italy)
Publication Date:
OSTI Identifier:
20779132
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 88; Journal Issue: 16; Other Information: DOI: 10.1063/1.2194315; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; COPPER; COPPER OXIDES; CURRENT DENSITY; DEPOSITION; EFFICIENCY; ELECTRIC POTENTIAL; ELECTRICAL FAULTS; FABRICATION; FILL FACTORS; FILMS; HETEROJUNCTIONS; INDIUM COMPOUNDS; ION BEAMS; SOLAR CELLS; SPUTTERING; SUBSTRATES; TIN COMPOUNDS

Citation Formats

Mittiga, Alberto, Salza, Enrico, Sarto, Francesca, Tucci, Mario, and Vasanthi, Rajaraman. Heterojunction solar cell with 2% efficiency based on a Cu{sub 2}O substrate. United States: N. p., 2006. Web. doi:10.1063/1.2194315.
Mittiga, Alberto, Salza, Enrico, Sarto, Francesca, Tucci, Mario, & Vasanthi, Rajaraman. Heterojunction solar cell with 2% efficiency based on a Cu{sub 2}O substrate. United States. doi:10.1063/1.2194315.
Mittiga, Alberto, Salza, Enrico, Sarto, Francesca, Tucci, Mario, and Vasanthi, Rajaraman. Mon . "Heterojunction solar cell with 2% efficiency based on a Cu{sub 2}O substrate". United States. doi:10.1063/1.2194315.
@article{osti_20779132,
title = {Heterojunction solar cell with 2% efficiency based on a Cu{sub 2}O substrate},
author = {Mittiga, Alberto and Salza, Enrico and Sarto, Francesca and Tucci, Mario and Vasanthi, Rajaraman},
abstractNote = {We report on the fabrication of heterojunction solar cells made by deposition of transparent conducting oxide (TCO) films on Cu{sub 2}O substrates. The TCO films have been grown by ion beam sputtering on good quality Cu{sub 2}O sheets prepared by oxidizing copper at a high temperature. The best solar cell has reached an open-circuit voltage of 0.595 V, a short-circuit current density of 6.78 mA/cm{sup 2}, a fill factor of 50%, and a conversion efficiency of 2% under simulated AM1.5G illumination, which is the highest efficiency value reported for this kind of heterojunction devices. These devices represent a good starting point for the development of very low cost solar cells.},
doi = {10.1063/1.2194315},
journal = {Applied Physics Letters},
number = 16,
volume = 88,
place = {United States},
year = {Mon Apr 17 00:00:00 EDT 2006},
month = {Mon Apr 17 00:00:00 EDT 2006}
}
  • We demonstrate cuprous oxide (Cu{sub 2}O) based metal insulator semiconductor Schottky (MIS-Schottky) solar cells with efficiency exceeding 3%. A unique direct growth technique is employed in the fabrication, and hexagonal boron nitride (h-BN) serves simultaneously as a passivation and insulation layer on the active Cu{sub 2}O layer. The devices are the most efficient of any Cu{sub 2}O based MIS-Schottky solar cells reported to date.
  • The resistivity was controlled in the range of 10{sup 3} to 10{sup −2} Ω cm in polycrystalline p-type Cu{sub 2}O sheets (incorporating sodium (Na)), which are suitable for Cu{sub 2}O-based heterojunction solar cell applications. The Na-doped Cu{sub 2}O sheets exhibited a hole concentration that ranged from 10{sup 13} to 10{sup 19 }cm{sup −3}. In particular, a hole concentration of 10{sup 13}–10{sup 16 }cm{sup −3} was obtained while maintaining a high Hall mobility above 100 cm{sup 2}/V s, and, in addition, a degenerated semiconductor exhibiting metallic conduction was realized with a hole concentration above about 1 × 10{sup 19 }cm{sup −3}. The mechanism associated with the Namore » doping can be explained by a copper vacancy produced due to charge compensation effects that result when a Na atom is incorporated at an interstitial site in the Cu{sub 2}O lattice. For solar cell applications, the use of the Cu{sub 2}O:Na sheet in a heterojunction solar cell successfully improved the obtained efficiency over that found in heterojunction solar cells fabricated using an undoped Cu{sub 2}O sheet.« less
  • In this study, the chemical structure of the Zn(O,S)/Cu(In,Ga)Se 2 interface in high-efficiency photovoltaic devices is investigated using X-ray photoelectron and Auger electron spectroscopy, as well as soft X-ray emission spectroscopy. We find that the Ga/(Ga+In) ratio at the absorber surface does not change with the formation of the Zn(O,S)/Cu(In,Ga)Se 2 interface. Furthermore, we find evidence for Zn in multiple bonding environments, including ZnS, ZnO, Zn(OH) 2, and ZnSe. We also observe dehydrogenation of the Zn(O,S) buffer layer after Ar+ ion treatment. Similar to high-efficiency CdS/Cu(In,Ga)Se 2 devices, intermixing occurs at the interface, with diffusion of Se into the buffer,more » and the formation of S—In and/or S—Ga bonds at or close to the interface.« less
  • The effect of copper diffusion from the p-Cu/sub 2/S into the n-CdS region, due to heat treatment, in a Cu/sub 2/S/CdS heterojunction photovoltaic cell is investigated, using the energy band diagram resulting from a modified Schottky barrier in the CdS and the solution of the one-dimensional Poisson's equation with appropriately assumed boundary conditions and diffusion model of Gaussian profile for the Cu-acceptor concentration in the CdS. The variation of the short-circuit current density J/sub sc/ and that of the fill factor of the device with the copper-diffusion parameters zeta and L/sub A/ are analyzed. Here zeta denotes the fraction ofmore » copper acceptors within the Cu/sub 2/S region which has diffused into the n-CdS region and L/sub A/ is the mean diffusion length of copper. It is shown that both J/sub sc/ and fill factor decrease with zeta while they increase with L/sub A/. The sample calculation, made for room-temperature operation of the device, indicates that the reduction in J/sub sc/ and fill factor can be appreciable if the amount of copper diffused is sufficient. This theoretical observation is consistent with some experimental results which have been reported elsewhere.« less
  • No abstract prepared.