Free Energy
Páginas: 20 (4803 palabras)
Publicado: 3 de marzo de 2013
SUBJECT AREAS:
MATERIALS NANOBIOTECHNOLOGY MOLECULAR BIOLOGY NANOPHOTONICS
Self-assembled photosystem-I biophotovoltaics on nanostructured TiO2 and ZnO
Andreas Mershin1, Kazuya Matsumoto2, Liselotte Kaiser2, Daoyong Yu2, Michael Vaughn3, Md. K. Nazeeruddin4, Barry D. Bruce3, Michael Graetzel4 & Shuguang Zhang2
Center for Bits and Atoms, NE47-383, Massachusetts Institute of Technology, 77Massachusetts Ave. Cambridge, MA 02139, USA, 2Laboratory for Molecular Self-Assembly, NE47-379, Massachusetts Institute of Technology, 500 Technology Square, Cambridge, MA 02139, USA, 3Biochemistry, Cellular and Molecular Biology & Chemical and Biomolecular Engineering, 226 Hesler Biology Bldg., University of Tennessee at Knoxville, TN 37996, USA, 4Laboratory for Photonics and Interfaces (Instituteof Chemical Science and Engineering), Ecole Polytechnique Federale de Lausanne, Lausanne, CH-1015, Switzerland.
1
Received 30 August 2011 Accepted 5 January 2012 Published 2 February 2012
Correspondence and requests for materials should be addressed to A.M. (mershin@mit. edu)
The abundant pigment-protein membrane complex photosystem-I (PS-I) is at the heart of the Earth’s energy cycle.It is the central molecule in the ‘‘Z-scheme’’ of photosynthesis, converting sunlight into the chemical energy of life. Commandeering this intricately organized photosynthetic nanocircuitry and re-wiring it to produce electricity carries the promise of inexpensive and environmentally friendly solar power. We here report that dry PS-I stabilized by surfactant peptides functioned as both thelight-harvester and charge separator in solar cells self-assembled on nanostructured semiconductors. Contrary to previous attempts at biophotovoltaics requiring elaborate surface chemistries, thin film deposition, and illumination concentrated into narrow wavelength ranges the devices described here are straightforward and inexpensive to fabricate and perform well under standard sunlight yielding opencircuit photovoltage of 0.5 V, fill factor of 71%, electrical power density of 81 mW/cm2 and photocurrent density of 362 mA/cm2, over four orders of magnitude higher than any photosystem-based biophotovoltaic to date.
S-I precisely orchestrates 96 chlorophyll molecules with electron donors and acceptors1 (Fig 1 a) achieving efficient coherent energy transfer2 and near-unity charge separationquantum yield at ambient temperatures3,4. This is a feat unmatched by any man-made photoelectronic device and has led to PS-I being studied as a candidate for many nanobioelectronic applications5–8, as well as being the original inspiration behind the dyesensitized solar cell (DSC)9. So far, research on PS-I biophotovoltaics has focused on proof-of-principle devices, studying immobilized PS-I complexesand isolated reaction centers (RC) in self-assembled monolayers (SAMs) on flat electrodes5–8. Two main obstacles hinder biophotovoltaics from being a more widely studied technology, constantly improved by many independent researchers. Firstly, while extracting PS-I from a variety of abundant sources is easy, drying this extract on electrodes results in rapid loss of function due to denaturation.Secondly, the electrical power output of biophotovoltaics to date has been so low5–8, that they were of little practical interest and the characterization necessary to improve their performance required cumbersome, expensive to iterate-optimize methods. For instance, in order to obtain measureable photocurrents it was necessary to make up for the low absorption cross sections of the nearlytransparent active SAMs. In prior studies this was addressed by using either laser light with power equivalent to 100 times that of standard air-mass 1.5 (AM1.5) sunlight5, or incoherent monochromatic light6 in both cases precisely tuned to the pigment absorption maxima –an unrealistic emulation of real-world conditions requiring elaborate instrumentation.
P
Results We have removed these two...
MATERIALS NANOBIOTECHNOLOGY MOLECULAR BIOLOGY NANOPHOTONICS
Self-assembled photosystem-I biophotovoltaics on nanostructured TiO2 and ZnO
Andreas Mershin1, Kazuya Matsumoto2, Liselotte Kaiser2, Daoyong Yu2, Michael Vaughn3, Md. K. Nazeeruddin4, Barry D. Bruce3, Michael Graetzel4 & Shuguang Zhang2
Center for Bits and Atoms, NE47-383, Massachusetts Institute of Technology, 77Massachusetts Ave. Cambridge, MA 02139, USA, 2Laboratory for Molecular Self-Assembly, NE47-379, Massachusetts Institute of Technology, 500 Technology Square, Cambridge, MA 02139, USA, 3Biochemistry, Cellular and Molecular Biology & Chemical and Biomolecular Engineering, 226 Hesler Biology Bldg., University of Tennessee at Knoxville, TN 37996, USA, 4Laboratory for Photonics and Interfaces (Instituteof Chemical Science and Engineering), Ecole Polytechnique Federale de Lausanne, Lausanne, CH-1015, Switzerland.
1
Received 30 August 2011 Accepted 5 January 2012 Published 2 February 2012
Correspondence and requests for materials should be addressed to A.M. (mershin@mit. edu)
The abundant pigment-protein membrane complex photosystem-I (PS-I) is at the heart of the Earth’s energy cycle.It is the central molecule in the ‘‘Z-scheme’’ of photosynthesis, converting sunlight into the chemical energy of life. Commandeering this intricately organized photosynthetic nanocircuitry and re-wiring it to produce electricity carries the promise of inexpensive and environmentally friendly solar power. We here report that dry PS-I stabilized by surfactant peptides functioned as both thelight-harvester and charge separator in solar cells self-assembled on nanostructured semiconductors. Contrary to previous attempts at biophotovoltaics requiring elaborate surface chemistries, thin film deposition, and illumination concentrated into narrow wavelength ranges the devices described here are straightforward and inexpensive to fabricate and perform well under standard sunlight yielding opencircuit photovoltage of 0.5 V, fill factor of 71%, electrical power density of 81 mW/cm2 and photocurrent density of 362 mA/cm2, over four orders of magnitude higher than any photosystem-based biophotovoltaic to date.
S-I precisely orchestrates 96 chlorophyll molecules with electron donors and acceptors1 (Fig 1 a) achieving efficient coherent energy transfer2 and near-unity charge separationquantum yield at ambient temperatures3,4. This is a feat unmatched by any man-made photoelectronic device and has led to PS-I being studied as a candidate for many nanobioelectronic applications5–8, as well as being the original inspiration behind the dyesensitized solar cell (DSC)9. So far, research on PS-I biophotovoltaics has focused on proof-of-principle devices, studying immobilized PS-I complexesand isolated reaction centers (RC) in self-assembled monolayers (SAMs) on flat electrodes5–8. Two main obstacles hinder biophotovoltaics from being a more widely studied technology, constantly improved by many independent researchers. Firstly, while extracting PS-I from a variety of abundant sources is easy, drying this extract on electrodes results in rapid loss of function due to denaturation.Secondly, the electrical power output of biophotovoltaics to date has been so low5–8, that they were of little practical interest and the characterization necessary to improve their performance required cumbersome, expensive to iterate-optimize methods. For instance, in order to obtain measureable photocurrents it was necessary to make up for the low absorption cross sections of the nearlytransparent active SAMs. In prior studies this was addressed by using either laser light with power equivalent to 100 times that of standard air-mass 1.5 (AM1.5) sunlight5, or incoherent monochromatic light6 in both cases precisely tuned to the pigment absorption maxima –an unrealistic emulation of real-world conditions requiring elaborate instrumentation.
P
Results We have removed these two...
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