Interface Recombination & Emission Applied to Explain Photosynthetic Mechanisms for (e–, h+) Charges’ Separation

Marco Sacilotti, Denis Chaumont, Claudia Brainer Mota, Thiago Vasconcelos, Frederico Dias Nunes, Marcelo Francisco Pompelli, Sergio Luiz Morelhao, Anderson S. L. Gomes

Departament of Eletronics and Systems, Federal University of Pernambuco, Recife, Brazil.
Department of Physics, Federal University of Pernambuco, Recife, Brazil.
Institute of Physics, University of Sao Paulo, Sao Paulo, Brazil.
Nanoform Group ICB & UFR Science and Technology, University of Burgundy, Dijon, France.
Plant Physiology Laboratory, Department of Botany, Federal University of Pernambuco, Recife, Brazil.

DOI: 10.4236/wjnse.2012.22010                

Abstract

To copy natural photosynthesis process we need to understand and explain the physics underneath its first step mechanism, which is “how to separate electrical charges under attraction”. But this Nature’s nanotechnological creation is not yet available to the scientific community. We present a new interpretation for the artificial and natural photosynthetic mechanism, concerning the electrical charges separation and the spent energy to promote the process. Interface (e–, h+) recombination and emission is applied to explain the photosynthetic mechanisms. This interpretation is based on energy bands relative position, the staggered one, which under illumination promotes (e–, h+) charges separation through the action of an interface electric field and energy consumption at the interface of both A/B generic materials. Energy band bending is responsible by the interface electric field (and the driving force) for the charges separation. This electric field can be as high or above that for p-n semiconductor junctions (10⁴ - 10⁵ V/cm). This physical effect is not considered by most of the researches. Without an electric field and without spending energy to separate electrical charges, any other existing model violates physical laws. The staggered energy band type is the only energetic configuration that permits charges separation under illumination and energy loss to perform the process. Application to natural photosynthesis and artificial photovoltaic material and their energetic configurations are discussed. Examples for A/B being III-V/III-V, TiO₂/materials and II-VI/II-VI staggered energy band gap pairs are presented. In the proposed quantum mechanism, plants are able to eliminate most of the 79% of the absorbed visible light, according to the published reflection and transmission data. Moreover, the proposed mechanism can be applied to explain green fluorescent protein - GFP, charge transfer states - CTS and Fluorescent Resonance Energy Transfer - FRET. As recent literature experimental results propose photosynthesis as a quantum controlled mechanism, our proposition goes forward this direction.

Keywords

Solar Energy; Renewable Energy; Photovoltaic; Photosynthesis; Type II Interfaces; Staggered Interface; Interface Emission; Interface Recombination; Quantum Photosynthesis; Solar Cell; FRET; GFP

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	O. Kruse, J. Rupprecht, J. Mussgnug, G. Dismukes and B. Hankamer, “Photosynthesis: A Blueprint for Solar Energy Capture and Biohydrogen Production Technologies,” Photochemical & Photobiological Sciences, Vol. 4, No. 12, 2005, pp. 957-969. doi:10.1039/b506923h
[2]	H. Peter Raven, F. Ray Evert and S. Eichhorn, “Biologia Vegetal,” 6th Edition, Guanabara Koogan, Rio de Janeiro, 2001, p. 125, 136, 138, 148.
[3]	G. C. Dismukes and R. Blankenship, “The Origin and Evolution of Photosynthetic Oxygen Production,” In: B. King, Ed., Encyclopedia of Inorganic Chemistry, 2nd Edition, John Wiley & Sons, Hoboken, 2005, pp. 6696-6707.
[4]	H. Kroemer, “Nobel Lecture: Quasielectric Fields and Band Offsets: Teaching Electrons New Tricks,” Reviews of Modern Physics, Vol. 73, No. 3, 2001, pp. 783-793. doi:10.1103/RevModPhys.73.783
[5]	H. Kroemer, “Staggered-Lineup Heterojunctions as Sources of Tunable Below-Gap Radiation: Operating Principle and Semiconductor Selection,” IEEE Electron Device Letters, Vol. 4, No. 1, 1983, pp. 20-22.
[6]	L. Esaki, “A Bird’s-Eye View on the Evolution of Semiconductors Superlattices and Quantum Wells,” IEEE Quantum Electronics, Vol. 22, No. 9, 1986, pp. 1611-1624. doi:10.1109/JQE.1986.1073162
[7]	H. Kroemer, “Barrier Control and Measurements: Abrupt Semiconductor Heterojunctions,” Journal of Vacuum Science & Technology B, Vol. 2, No. 3, 1984, pp. 433-439.
[8]	M. Gratzel, “Photoelectrochemical Cells,” Nature, Vol. 414, No. 15, 2001, pp. 338-344. doi:10.1038/35104607
[9]	M. Sacilotti, P. Abraham, M. Pitaval, M. Ambri, T. Benyattou, A. Tabata, M. Perez, P. Motisuke, R. Landers, A. Lecore and S. Loualiche, “Structural and Optical Properties of AlInAs/InP and GaPSb/InP Type II Interfaces,” Canadian Journal of Physics, Vol. 74, No. 5-6, 1996, pp. 202-208. doi:10.1139/p96-032
[10]	M. S. Sze, “Physics of Semiconductor Devices,” 1st Edition, John Wiley & Sons Inc., Chichester, 1969, pp. 32-38, & 3rd Edition, 2007, p. 27, 58, 79, 104, 123, 128, 134, 457, 601, 663.
[11]	F. De Angelis, S. Fantacci and A. Selloni, “Alignment of the Dye’s Molecular Levels with the TiO2 Band Edges in Dye-Sensitized Solar Cells: A Dft-Tddft Study,” Nanotechnology, Vol. 19, No. 42, 2008, Article ID: 424002-09. doi:10.1088/0957-4484/19/42/424002
[12]	M. Sacilotti, E. Almeida, C. Brainer, F. Dias Nunes, Th. Vasconcelos and M. Sundheimer, “A Proposed Quantum Mechanics Mechanism for (e–, h+) Charges Separation Applied to Photosynthesis and Energy Production Efficiency Improovement,” Optical Society of America, Frontiers in Optics, San Jose, 11 October 2009. http://www.opticsinfobase.org/viewmedia.cfm?uri=FiO-2009-PDPC5&seq=0.
[13]	J. R. Bolton, “Solar Power and Fuels,” Academic Press Inc., New York, 1977, p. 229.
[14]	V. Sundstrm, T. Pullerits and R. Grondelle, “Photosynthetic Light-Harvesting: Reconciling Dynamics and Structure of Purple Bacterial LH2 Reveals Function of Photosynthetic Unit,” The Journal of Physical Chemistry B, Vol. 103, No. 13, 1999, pp. 2327-2346. doi:10.1021/jp983722+
[15]	L. O. Bjorn, G. Papageorgiou, R. Blankenshi and K. Govindjee, “A View Point: Why Chlorophylla?” Photosynthesis Research, Vol. 99, No. 2, 2009, pp. 85-98.
[16]	L. Wei, C. Liu, Y. Zhou, Y. Bai, X. Feng, Z. Yang, L. Lu, X. Lu and K. Chan, “Enhanced Photovoltaic Activity in Anatase/TiO2(B) Core-Shell Nanofiber,” The Journal of Physical Chemistry C, Vol. 112, No. 51, 2008, pp. 2539-20545.
[17]	S. S. Srinivasan, J. Wade and E. Stefanakos, “Visible Light Photocatalysis via CdS/TiO2 Nanocomposite Materials,” Journal of Nanomaterials, Vol. 2006, 2006, pp. 1-7, Article ID: 87326. doi:10.1155/JNM/2006/87326
[18]	I. Robel, V. Subramanian, M. Kuno and P. Kamat, “Quantum Dot Solar Cells. Harvesting Light Energy with CdSe Nanocrystals Molecularly Linked to Mesoscopic TiO2 Films,” Journal of the American Chemical Society, Vol. 128, No. 7, 2006, pp. 2385-2393. doi:10.1021/ja056494n
[19]	P. V. Kamat, “Quantum Dot Solar Cells. Semiconductor Nanocrystals as Light Harvesters,” The Journal of Physical Chemistry C, Vol. 112, No. 48, 2009, pp. 18737-18753.
[20]	D. Robert, “Photosensitization of TiO2 by MxSy and MxSy Nanoparticles for Heterogeneous Photocatalysis Applications,” Catalysis Today, Vol. 122, No. 1-2, 2007, pp. 20-26. doi:10.1016/j.cattod.2007.01.060
[21]	J. Zhang, H. Zhu, S. Zheng, F. Pan and T. Wang, “TiO2 Film/Cu2O Microgrid Heterojunction with Photocatalytic Activity under Solar Light Irradiation,” Applied Materials & Interfaces, Vol. 1, No. 10, 2009, pp. 2111-2114. doi:10.1021/am900463g
[22]	M. Fox, “Optical Properties of Solids. Oxford Master Series in Condensed Matter Physics,” Oxford University Press, Oxford, 2001, pp. 76-78.
[23]	P. Abraham, M. Perez, T. Benyattou, G. Guillot, M. Sacilotti and X. Letartre, “Photoluminescence and Band Offsets of AlInAs/InP,” Semiconductor Science and Technology, Vol. 10, No. 12, 1995, pp. 1585-1595. doi:10.1088/0268-1242/10/12/006
[24]	M. Sacilotti, P. Motisuke, Y. Monteil, P. Abraham, F. Iikawa, C. Montes, M. Furtado, L. Horiuchi, R. Landers, J. Morais, L. Cardoso, J. Decobert and B. Waldman, “Growth and Characterization of Type-II/Type-I AlGaInAs/InP Interfaces,” Journal of Crystal Growth, Vol. 124, No. 1-4, 1992, pp. 589-595. doi:10.1016/0022-0248(92)90522-K
[25]	R. Sakamoto, T. Kohnot, T. Kamiyoshi, M. Inoue, S. Nakajima and H. Hayashi, “Optical Analysis of Hot Carrier Distribution and Transport Properties in InP/AlInAs Type II Heterostructures,” Semiconductor Science and Technology, Vol. 7, No. 3B, 1992, pp. B271-B273. doi:10.1088/0268-1242/7/3B/066
[26]	A. Selloni, “Anatase Shows Its Reactive Side,” Nature Materials, Vol. 7, 2008, pp. 613-615. doi:10.1038/nmat2241
[27]	S. Kumar, M. Jones, S. Lo and G. Scholes, “Nanorod Heterostructures Showing Photoinduced Charge Separation,” Small, Vol. 3, No. 9, 2007, pp. 1633-1639. doi:10.1002/smll.200700155
[28]	G. Scholes, “Controlling the Optical Properties of Inorganic Nanoparticles,” Advanced Functional Materials, Vol. 18, No. 8, 2008, pp. 1157-1172. doi:10.1002/adfm.200800151
[29]	S. Kumar and G. Scholes, “Colloidal Nanocrystal Solar Cells,” Microchim Acta, Vol. 160, No. 3, 2008, pp. 315-325. doi:10.1007/s00604-007-0806-z
[30]	M. Sacilotti, E. Almeida, C. Mota, F. D. Nunes and A. S. L. Gomes, “Can the Photosynthesis First Step Quantum Mechanism Be Explained?” http://arxiv.org/abs/1005.1337
[31]	M. Sacilotti, E. Almeida, C. Mota, Th. Vasconcelos, F. D. Nunes and A. S. L. Gomes, “A New Quantum Optical Structure to Separate Attracting Electrical Charges,” The Latin America Optics and Photonics Conference, Vol. 1. 2010, pp. 1-4. http://www.opticsinfobase.org/abstract.cfm?uri=LAOP-2010-TuA3.
[32]	S. Yin and T. Sato, “Synthesis and Photocatalytic Properties of Fibrous Titania Prepared from Protonic Layered Tetratitanate Precursor in Supercritical Alcohols,” Industrial & Engineering Chemistry Research, Vol. 39, No. 12, 2000, pp. 4526-4530. doi:10.1021/ie000165g
[33]	M. R. Hoffmann, S. T. Martin, W. Choi and D. W. Bahnemannt, “Environmental Applications of Semiconductor Photocatalysis,” Chemical Reviews, Vol. 95, No. 1, 1995, pp. 69-96. doi:10.1021/cr00033a004
[34]	A. Fujishima and K. Honda, “Electrochemical Photolysis of Water at a Semiconductor Electrode,” Nature, Vol. 238, No. 7, 1972, pp. 37-38. doi:10.1038/238037a0
[35]	J.-L. Brédas, “Molecular Understanding of Organic Solar Cells: The Challenges,” Accounts of Chemical Research, Vol. 42, No. 11, 2009, pp. 1691-1699. doi:10.1021/ar900099h
[36]	H. Ishii, K. Sugiyama, E. Ito and K. Seki, “Energy Level Alignment and Interfacial Electronic Structures at Organic/Metal and Organic/Organic Interfaces,” Advanced Materials, Vol. 11, No. 8, 1999, pp. 605-625. doi:10.1002/(SICI)1521-4095(199906)11:8<605::AID-ADMA605>3.0.CO;2-Q
[37]	T.-C. Tseng, Ch. Urban, Y. Wang, R. Otero, S. Tait, M. Alcami, D. Ecija, M. Trelka, J. M. Gallego, N. Lin, M. Konuma, U. Starke, A. Nefedov, A. Langner, Ch. Woll, M. Herranz, F. Martin, K. Kern and R. Miranda, “Charge-Transfer-Induced Structural Rearrangements at Both Sides of Organic/Metal Interfaces,” Nature Chemistry, Vol. 2, 2010, pp. 374-379. doi:10.1038/nchem.591
[38]	C. Santato and F. Rosei, “Seeing Both Sides,” Nature Chemistry, Vol. 2, No. 5, 2010, pp. 344-345. doi:10.1038/nchem.636
[39]	M. Broglia, “Blue-Green Laser-Induced Fluorescence from Intact Leaves: Actinic Light Sensitivity and Subcellular Origins,” Applied Optics, Vol. 32, No. 3, 1993, pp. 334-338. doi:10.1364/AO.32.000334
[40]	E. Chappelle, F. Wood, W. Newcomb and J. Mcmurtrey, “Laser-Induced Fluorescence of Green Plants. LIF Spectral Signatures of Five Major Plant Types,” Applied Optics, Vol. 24, No. 1, 1985, pp. 74-80. doi:10.1364/AO.24.000074
[41]	T. Gillbro and R. Cogdell, “Carotenoid Fluorescence,” Chemical Physics Letters, Vol. 158, No. 3-4, 1989, pp. 312-316. doi:10.1016/0009-2614(89)87342-7
[42]	I. Terashima, T. Fujita, T. Inoue, W. Chow and R. Oguchi, “Green Light Drives Leaf Photosynthesis More Efficiently than Red Light in Strong White Light: Revisiting the Enigmatic Question of Why Leaves Are Green,” Plant & Cell Physiology, Vol. 50, No. 4, 2009, pp. 684-697. doi:10.1093/pcp/pcp034
[43]	A. P. de Souza, M. Gaspar, E. A. da Silva, E. C. Ulian, A. J. Waclawovsky, M. Y. Nishiyama Jr., R. V. dos Santos, M. M. Teixeira, G. M. Souza and M. S. Buckeridge, “Elevated CO2 Increases Photosynthesis, Biomass and Productivity, and Modifies Gene Expression in Sugarcane,” Plant, Cell & Environment, Vol. 31, No. 8, 2008, pp. 1116-1127. doi:10.1111/j.1365-3040.2008.01822.x
[44]	A. P. de Souza and M. S. Buckeridge, “Photosynthesis in Sugarcane and Its Strategic Importance to Face the Global Climatic Change,” In: Cortez LAB, Ed., Sugarcane Bioethanol: R & D for Productivity and Sustainability, Edgard Blucher, S?o Paulo, 2010, pp. 320-323.
[45]	Y. H. Su, S. L. Tu, S. W. Tseng, Y. C. Chang, S. H. Chang and W. M. Zhang, “Influence of Surface Plasmon Resonance on the Emission Intermittency of Photoluminescence from Gold Nano-Sea-Urchins,” Nanoscale, Vol. 2, No. 12, 2010, pp. 2639-2646. doi:10.1039/c0nr00330a
[46]	S. Blitz, “Lettuce Carotenoids Affected by UV Light in Greenhouse,” 2009. http://www.ars.usda.gov/is/np/Fnrb/fnrb0409.htm#lettuce
[47]	M. Chattoraj, B. A. King, G. U. Bublitz and S. G. Boxer, “Ultra-Fast Excited State Dynamics in Green Fluorescent Protein: Multiple States and Proton Transfer,” Proceedings of the National Academy of Sciences of the United States of America, Vol. 93, No. 16, 1996, pp. 8362-8367. doi:10.1073/pnas.93.16.8362
[48]	Q. Xiangfei, M. Slootsky and S. Forrest, “Stacked White Organic Light Emitting Devices Consisting of Separate Red, Green, and Blues Elements,” Applied Physics Letters, Vol. 93, No. 19, 2008, pp. 193306-193313. doi:10.1063/1.3021014
[49]	Y. Sun and S. Forrest, “High-Efficiency White Organic Light Emitting Devices with Three Separate Phosphorescent Emission Layers,” Applied Physics Letters, Vol. 91, No. 26, 2007, Article ID: 263503-26356. doi:10.1063/1.2827178
[50]	L. Koster, E. Smits, V. Mihailetchi and P. Blom, “Device Model for the Operation of Polymer/Fullerene Bulk Heterojunctions Solar Cells,” Physical Review B, Vol. 72, No. 8, 2005, Article ID: 085205-085214. doi:10.1103/PhysRevB.72.085205
[51]	J. J. Hall, J. Cornil, D. Santos, R. Silbey, D. Hwang, A. Holmes, J.-L. Brédas and R. Friend, “Charge and Energy Transfer Processes at Polymer/Polymer Interfaces: A Joint Experimental and Theoretical Study,” Physical Review B, Vol. 60, No. 8, 1999, pp. 5721-5727. doi:10.1103/PhysRevB.60.5721
[52]	C. Soci, I. Hwang, D. Moses, Z. Zhu, D. Walter, R. Gaudiana, C. Bradec and A. Heeger, “Photoconductivity of a Low-Bandgap Conjugated Polymer,” Advanced Functional Materials, Vol. 17, No. 4, 2007, pp. 632-636. doi:10.1002/adfm.200600199
[53]	X. Gong, M. Robinson, J. Ostrowski, D. Moses, G. Bazan and A. J. Heeger, “High-Efficiency Polymer-Based Electrophosphorescent Devices,” Advanced Materials, Vol. 14, No. 8, 2002, pp. 581-585. doi:10.1002/1521-4095(20020418)14:8<581::AID-ADMA581>3.0.CO;2-B
[54]	K. Lee and A. J. Heeger, “Optical Investigation of Intra and Interchain Charge Dynamics in Conducting Polymers,” Synthetic Metals, Vol. 128, No. 3, 2002, pp. 279-282. doi:10.1016/S0379-6779(02)00006-1
[55]	M. Koppe, M. Scharber, C. Brabec, W. Duffy, M. Heeney and I. McCulloch, “Polyterthiophenes as Donors for Polymer Solar Cells,” Advanced Functional Materials, Vol. 17, No. 8, 2007, pp. 1371-1376. doi:10.1002/adfm.200600859
[56]	A. J. Heeger, “The Plastic-Electronics Revolution,” Information Display, Vol. 18, No. 2, 2002, pp. 18-20.
[57]	K. Coakley and M. McGehee, “Conjugated Polymer Photovoltaic Cells,” Chemistry of Materials, Vol. 16, No. 23, 2004, pp. 4533-4542. doi:10.1021/cm049654n
[58]	J. Szollosi, S. Damjanovich and L. Matyus, “Application of Fluorescence Energy Transfer in the Clinical Laboratory: Routine and Research,” Cytometry, Vol. 34, No. 4, 1998, pp. 159-179. doi:10.1002/(SICI)1097-0320(19980815)34:4<159::AID-CYTO1>3.0.CO;2-B
[59]	S. Weiss, “Fluorescence Spectroscopy of Single Biomolecules,” Science, Vol. 283, No. 5408, 1999, pp. 1676-1683. doi:10.1126/science.283.5408.1676
[60]	A. Kahn, W. Zhao, W. Gao, H. Vazquez and F. Flores, “Doping-Induced Realignment of Molecular Levels at Organic-Organic Heterojunctions,” Chemical Physics, Vol. 325, No. 1, 2006, pp. 129-137.
[61]	Th. F?rster, “Intermolecular Energy Migration and Fluorescence,” Ann Physik, Vol. 2, No. 1-2, 1948, pp. 55-75.
[62]	P. Held, “An Introduction to Fluorescence Resonance Energy Transfer Technology and Its Application in Bioscience,” Bio Tek. http://www.biotek.com/resources/docs/Fluorescence_Resonance_Energy_Transfer_Technology_FRET_App_Note.pdf .
[63]	P. L. Southwick, L. A. Ernst, E. W. Tauriello, S. R. Parker, R. B. Mujumdar, S. R. Mujumdar, H. A. Clever, and A. S. Waggoner, “Cyanine Dye Labeling Reagents— Carboxymethylindocyanine Succinimidyl Esters,” Cytometry, Vol. 11, No. 3, 1990, pp. 418-430. doi:10.1002/cyto.990110313
[64]	J. Herek, W. Wohlleben, R. Cogdell, D. Zeidler and M. Motzkus, “Quantum Control of Energy Flow in Light Harvesting,” Nature, Vol. 417, 2002, pp. 533-535.
[65]	G. Fleming and G. Scholes, “Quantum Mechanics for Plants,” Nature, Vol. 431, 2004, pp. 256-257.
[66]	T. Brixner, J. Stenger, H. Vaswani, M. Cho, R. Blankenship and G. Fleming, “Two-Dimensional Spectroscopy of Electronic Coupling in Photosynthesis,” Nature, Vol. 434, 2005, pp. 625-628.
[67]	R. Sension, “Quantum Path to Photosyntesis,” Nature, Vol. 446, 2007, pp. 740-741.
[68]	G. Engel, T. Calhoun, E. Read, T. Ahn, T. Man?al, Y. Cheng, R. Blankenship and G. Fleming, “Evidence for Wavelike Energy Transfer through Quantum Coherence in Photosynthetic Systems,” Nature, Vol. 446, 2007, pp. 782-786.
[69]	G. Engel and G. Fleming, “Quantum Secrets of Photosynthesis Revealed,” 2007. file:///Users/sacilotti/Desktop/ToutFotosintese:Catalise:WOLED/PhotosynthesisQuantum/Quantum%20secrets%20of%20photosynthesis%20revealed.webarchive
[70]	M. Schirber “The Quantum Dimension of Photosynthesis,” 2009. http://focus.aps.org/story/v23/st5#author
[71]	I. Mercer, Y. E. Kajumba, J. Marangos, J. Tisch, M. Gabrielsen, R. Cogdell, E. Springate and E. Turcu, “Instantaneous Mapping of Coherently Coupled Electronic Transitions and Energy Transfers in a Photosynthetic Complex Using Angle-Resolved Coherent Optical Wave-Mixing,” Physical Review Letters, Vol. 102, No. 5, 2009, Article ID: 057402-4. doi:10.1103/PhysRevLett.102.057402
[72]	S. Seager, E. Turner, J. Schafer and E. Ford, “Vegetation’s Red Edge: A Possible Spectroscopic Biosignature of Extraterrestrial Plants,” 2005. http://Arxiv:astro-phy/0503302v1
[73]	P. Pearson, R. Bergstrn and S. Lunell, “Quantum Chemical Study of Photoinjection in Dye-Sensitized TiO2 Nanopaticles,” The Journal of Physical Chemistry B, Vol. 104, No. 44, 2000, pp. 10349-10351.
[74]	J. Sambur, Th. Novet and B. Parkinson, “Multiple Exciton Collection in a Sensitized Photovoltaic System,” Science, Vol. 330, No. 6000, 2010, pp. 63-66. doi:10.1126/science.1191462
[75]	Z. Yang, T. Xu, Y. Ito, U. Welp and W. Kwok, “Enhanced Electron Transport in Dye-Sensitized Solar Cells Using Short ZnO Nanotips on a Rough Metal Anode,” The Journal of Physical Chemistry C, Vol. 113, No. 47, 2009, pp. 20521-20526. doi:10.1021/jp908678x
[76]	J. Chen, W. Lei and W. Deng, “Reduced Charge Recombination in a Co-Sensitized Quantum Solar Cell with Two Different Sizes of CdSe Quantum Dot,” Nanoscale, Vol. 3, No. 2, pp. 674-677. doi:10.1039/C0NR0059IF
[77]	T. M. Clarke and J. R. Durrant, “Charge Photogeneration in Organic Solar Cells,” Chemical Reviews, Vol. 110, No. 11, 2010, pp. 6736-6767. doi:10.1021/cr900271s
[78]	R. H. Friend, M. Phillips, A. Rao, M. Wilson, Z. Li and Ch. MacNeil, “Excitons and Charges at Organic Semiconductor Heterojunctions,” Faraday Discussion, Vol. 155, No. 1-10, 2012, pp. 339-348.
[79]	J. Servaites, M. Ratner and T. Marks, “Organic Solar Cells: A New Look at Traditional Models,” Energy & Environmental Science, Vol. 4, No. 11, 2011, pp. 4410-4422.
[80]	L. Hammarstrom and S. Styring, “Proton-Coupled Electron Transfer of Tyrosines in Photosystem II and Model Systems for Artificial Photosynthesis: The Role of a Redox-Active Link between Catalyst and Photosensitiser,” Energy & Environmental Science, Vol. 4, No. 7, 2011, pp. 2379-2388.
[81]	Ch. Herrero, A. Quaranta, W. Leibl, A. W. Rutherford and A. Aukauloo, “Artificial Photosynthetic Systems,” Energy & Environmental Science, Vol. 4, No. 7, 2011, pp. 2353-2365.
[82]	P. Marek, H. Hahn and T. Balaban, “On the Way to Biomimetic Dye Aggregate Solar Cells,” Energy & Environmental Science, Vol. 4, No. 7, 2011, pp. 2366-2378.
[83]	Th. Woolerton, S. Sheard, E. Pierce, S. Rasdale and F. Armstrong, “CO2 Photoreduction at Enzyme-Modified Metal Oxide Nanoparticles,” Energy & Environmental Science, Vol. 4, No. 7, 2011, pp. 2393-2399.
[84]	P. Poddutoori, D. Co, A. Samuel, C. Kim, T. Vagnini and M. Wasielewski, “Photoiniciated Multistep Charge Separation in Ferrocene-Zinc Porphyrin-Diiron Hydrogenase Model Complex Triads,” Energy & Environmental Science, Vol. 4, No. 7, 2011, pp. 2441-2450.
[85]	K. Shimura and H. Yoshida, “Heterogeneuous Photocatalytic Hydrogen Production from Water and Biomass Derivatives,” Energy & Environmental Science, Vol. 4, No. 7, 2011, pp. 2467-2481.
[86]	M. Freitag and E. Galoppini, “Molecular Host-Guest Complexes: Shielding of Guests on Semiconductor Surfaces,” Energy & Environmental Science, Vol. 4, No. 7, 2011, pp. 2482-2494.
[87]	A. Cannavale, M. Manca, F. Malara, L. de Marco, R. Cingolani and G. Gigli, “Highly Efficient Smart Photovoltachromic Devices with Tailored Electrolyte Composition,” Energy & Environmental Science, Vol. 4, No. 7, 2011, pp. 2567-2574.
[88]	A. A. Bakulin, A. Rao, V. G. Pavelyev, P. H. M. van Loosdrecht, M. S. Pshenichnikov, D. Niedzialek, J. Cornil, D. Beljonne and R. H. Friend, “The Role of Driving Energy and Delocalized States for Charge Separation in Organic Semiconductors,” Science, Vol. 335, No. 6074, 2012, pp. 1340-1344. http://www-oe.phy.cam.ac.uk/oepubs/oepubsummary.htm doi:10.1126/science.1217745.