Light Energy Conversion 

2007 Annual Research Summary


Review article on a energy conversion topic (ready reference with 350+ citations) 
Meeting the Clean Energy Demand: Nanostructure Architectures for Solar Energy Conversion
J. Phys. Chem. C, 111 (7), 2834 -2860, 2007.
(Need a copy? Send an email request to

During the last decade the nanomaterials have emerged as the new building blocks to construct light energy harvesting assemblies. Organic and inorganic hybrid structures that exhibit improved selectivity and efficiency towards catalytic processes have been designed.  Size dependent properties such as size quantization effects in semiconductor nanoparticles and quantized charging effects in metal nanoparticles provides the basis for developing new and effective systems.
  These nanostructures provide innovative strategies for designing next generation energy conversion devices. Recent efforts to synthesize nanostructures with well defined geometrical shapes (e.g., solid and hollow spheres, prisms, rods, wires) and their assembly as 2- and 3- dimensional assemblies has further expanded the possibility of developing new strategies for light energy conversion.

There are three major ways that one can utilize nanostructures for the design of solar energy conversion devices. The first one is to mimic the photosynthesis with donor-acceptor molecular assemblies and clusters.  The second one is the semiconductor assisted photocatalysis to produce fuels such as hydrogen. The third and most promising category is the nanostructure semiconductor based solar cells. Strategies to employ ordered assemblies of semiconductor and metal nanoparticles, inorganic-organic hybrid assemblies and carbon nanostructures in the energy conversion schemes are currently being explored in our laboratory.

               #1 in Google Search "Light Energy Conversion"

See Popular Presentations on Meeting the Clean Energy Challenge with Nanotechnology     or  Solar Energy - Beyond the Hype  (11 MB)

Read   Fast breaking paper on Quantum Dot Solar Cells  ( October 2007-ISI Web of Knowledge)
Robel, I., Subramanian, V., Kuno, M. and Kamat, P. V., Quantum Dot Solar Cells.  Harvesting Light Energy with CdSe Nanocrystals Molecularly Linked to Mesoscopic TiO2 Films. J. Am. Chem. Soc., 2005, 2385-2393

Read  one of 5 most cited papers on solar cells during last 2 years (ISI Web of Knowledge)
Hasobe, T., Imahori, H., Kamat, P. V. and Fukuzumi, S., Photovoltaic Cells using composite nanoclusters of porphyrins and fullerenes with gold nanoparticles. J. Am. Chem. Soc, 2005, 127, 1216-1228.

Our Research Focus.
  • To design heterogeneous assemblies consisting of  carbon nanostructures (fullerenes, carbon nanotubessensitization scheme etc) , semiconductor nanostructures, metal particles and sensitizing dyes for harvesting light energy

  • To elucidate the interfacial charge transfer processes in semiconductor/sensitizer systems.

  • To improve photoinduced charge separation in donor-acceptor type dyads and triads by binding them to metal nanostructures and/or semiconductor composites

  • To employ donor-acceptor based supramolecular systems (for example, fullerenes and porphyrins) and molecular clusters for in organic photovoltaic cells.

Thanks to our collaborators Profs. S. Hotchandani  (Univ. Of Tros Riveres, Canada)  Prof. K. George Thomas (RRL, India) and Prof. S. Fukuzumi (Osaka Univ., Japan)  who have collaborated on the projects related to  our solar energy conversion  research .  We also acknowledge thr continued research funding by the Department of Energy, Office of Basic Energy Sciences

Recent  Progress

  • Pioneered in the elucidation of interfacial charge transfer processes and introduction of composite semiconductor systems for improving the performance of dye sensitized solar cells
  • Probed the role of iodide and triiodide ions in deactivating the excited state of Ru(II)polypyridyl complex bound to TiO2.
  • Established the role of Fermi level equilibration in improving the energetics of semiconductor-metal systems.  A shift of 100-150 mV in the apparent Fermi level was achieved by depositing 2-3 nm Au nanoparticles on TiO2 nanostructures.
  • Achived a  photoconversion efficiency (IPCE ) of  60% and power conversion effeciency of 2% using Au-Porphyrin_C60 based molecular clusters.
  • Designed inorganic-organic hybrid assemblies for photoelectrochemical conversion of light energy
  • Employed cabon nanotubes as conduits to promote chargeseparation and charge transport in nanostructured semiconductor films

Recent Publications

 Robel, I.; Subramanian, V.; Kuno, M.; Kamat, P.V., Quantum Dot Solar Cells.  Harvesting Light Energy with CdSe Nanocrystals Molecularly Linked to Mesoscopic TiO2 Films. J. Am. Chem. Soc., 2006. 128, 2385-2393.

Hasobe, T.; Fukuzumi, S.; Kamat, P.V.,   Stacked-Cup Carbon Nanotubes for Photoelectrochemical Solar Cells. Angew. Chem. (Int.  Ed.), 2006. 45, 755-759.   NDRL 4623 Hasobe, T.; Hattori, S.; Kamat, P.V.; Fukuzumi, S., Supramolecular nanostructured assemblies of different types of porphyrins with fullerenes using TiO2 nanoparticles for light energy conversion. Tetrahedron, 2006. 62, 1937-1946.  NDRL 4606      

Robel, I., Bunker, B. and Kamat, P. V., SWCNT-CdS nanocomposite as light harvesting assembly. Photoinduced charge transfer interactions. Adv. Mater., 2005, 17, 2458-2463.  (doi:10.1002/adma.200500418)    NDRL 4583

Kamat, P. V., Photoelectrochemistry in Particulate Systems. 9. Photosensitized Reduction in a Colloidal Tio2 System Using Anthracene-9-Carboxylic Acid as the Sensitizer. J. Phys. Chem., 1989. 93 859-64.

Bedja, I., S. Hotchandani and P. V. Kamat, Preparation and Characterization of Thin Sno2 Nanocrystalline Semiconductor Films and Their Sensitization with Bis(2,2'-Bipyridine)(2,2'-Bipyridine-4-4'-Dicarboxylic Acid)Ruthenium Complex. J. Phys. Chem., 1994. 98 4133-4140.

Fessenden, R. W. and P. V. Kamat, Rate Constants for Charge Injection from Excited Sensitizer into SnO2, ZnO, and TiO2 Semiconductor Nanocrystallites. J. Phys. Chem., 1995. 99 12902-12906.

Sudeep, P. K., Ipe, B. I., George Thomas, K., George, M. V., Barazzouk, S., Hotchandani, S. and Kamat, P. V., Fullerene Functionalized Gold Nanoparticles. A self assembled Photoactive Antenna-Metal Nanocore Assembly. Nano Lett., 2002, 2, 29-35.
George Thomas, K. and Kamat, P. V., Chromophore Functionalized Gold Nanoparticles. Acc. Chem. Res., 2003, 36, 888-898 (Review Article)

Kamat, P. V., I. Bedja, S. Hotchandani and L. K. Patterson, Photosensitization of Nanocrystalline Semiconductor Films.  Modulation of Electron Transfer between Excited Ruthenium Complex and Sno2 Nanocrystallites with an Externally Applied Bias. J. Phys. Chem. B, 1996. 100 4900-4908. 

Nasr, C., S. Hotchandani, W. Y. Kim, R. H. Schmehl and P. V. Kamat, Photoelectrochemistry of Composite Semiconductor Thin Films.  Photosensitization of SnO2/CdS Coupled Nanocrystallites with a Ruthenium Complex. J. Phys. Chem. B, 1997. 101 7480-7487.

Liu, D., P. V. Kamat, K. George Thomas, K. J. Thomas, S. Das and M. V. George, Picosecond Dynamics of an Ir Sensitive Squaraine Dye. Role of Singlet and Triplet Excited States in the Photosensitization of TiO2 Nanoclusters. J. Chem. Phys., 1997. 106 6404-6410.

Das, S. and P. V. Kamat, Can Dye Aggregates Serve as Light Harvesting Antenna? Triplet-Triplet Energy Transfer between Excited Aggregates and Monomer in Aot/Heptane Solutions. J. Phys. Chem. B, 1999. 103 209-215.. 

Kamat, P. V., S. Barazzouk, K. George Thomas and S. Hotchandani, Electrodeposition of C60 Clusters on Nanostructured SnO2 Films for Enhanced Photocurrent Generation. J. Phys. Chem. B, 2000. 104 4014-4017.

Kamat, P. V., M. Haria and S. Hotchandani, C60 Cluster as an Electron Shuttle in a Ru(Ii)-Polypyridyl Sensitizer Based Photochemical Solar Cell. J. Phys. Chem. B, 2004. 108 5166-5170.

Hasobe, T., H. Imahori, S. Fukuzumi and P. V. Kamat, Quaternary Self-Organization of Porphyrin and Fullerene Units by Clusterization with Gold Nanoparticles on SnO2 Electrodes for Organic Solar Cells. J. Am. Chem. Soc., 2003. 125 14962-14963.

Hasobe, T., H. Imahori, P. V. Kamat and S. Fukuzumi, Photovoltaic Cells Using Composite Nanoclusters of Porphyrins and Fullerenes with Gold Nanoparticles. J. Am. Chem. Soc, 2004. 126 in press

In Popular Press

Reactive Reports: Fullerenes on Film

pccp covernanoscale charge transfernanotoday covercover

Highlights in

Robel, I.; Subramanian, V.; Kuno, M.; Kamat, P.V., Quantum Dot Solar Cells.  Harvesting Light Energy with CdSe Nanocrystals Molecularly Linked to Mesoscopic TiO2 Films. J. Am. Chem. Soc., 2006. 128, 2385-2393.

Heart Cut (An ACS Online Publication) April 3 2006
Laser Focus World April 2006 issue

Materials Today December 2004 Research News-Nanotoday Supplement  New Light on CNT's -Energy Generation


Home Page        Profile        Research           People       Synthetic Secrets       Publications       Useful Links