"Welcome to The Prashant Kamat lab at the University of Notre Dame! With the help of internal and external collaborations we have established a successful multidisciplinary research program in nanostructure architectures and energy conversion processes." - Prashant Kamat

Kamat Lab News

Wednesday, November 12, 2014Posted by Jeff Christians

Size-Dependent Photovoltaic Performance of CuInS2

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Size-Dependent Photovoltaic Performance of CuInS2 Quantum Dots Sensitized Solar Cells

Size-Dependent Photovoltaic Performance of CuInS2 Quantum Dots Sensitized Solar Cells

Abstract: The optical and electronic properties of quantum dots (QDs) which are drastically affected by their size have major impact on their performance in devices like solar cells. We now report the size dependent solar cell performance for CuInS2 QDs capped with 1-dodecanethiol. Pyramidal shaped CuInS2 QDs with diameter between 2.9 nm and 5.3 nm have been synthesized and assembled on mesoscopic TiO2 films by electrophoretic deposition. Time resolved emission and transient absorption spectroscopy measurements have ascertained the role of internal and surface defects in determining the solar cell performance. An increase in power conversion efficiency (PCE) was observed with increasing size of QDs, with maximum values of 2.14 and 2.51% for 3.9 and 4.3 nm size particles, respectively. The drop in PCE observed for larger QDs (5.3 nm) is attributed to decreased charge separation following bandgap excitation. Since the origin of photocurrent generation in CuInS2 QDSC arises from the defect dominated charge carriers it offers the opportunity to further improve the efficiency by controlling these defect concentrations.

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Monday, November 3, 2014Posted by Jeff Christians

Dual Nature of CH3NH3PbI3 Excited State

Read the latest paper from the Kamat Lab!

Dual Nature of the Excited State in Organic-Inorganic Lead Halide Perovskites

Dual Nature of the Excited State in Organic-Inorganic Lead Halide Perovskites

Abstract: The rapid increase in efficiency of methylammonium lead halide perovskite solar cells necessitates further investigation into the nature of perovskite absorption features and optical properties. Films obtained from the deposition of solutions containing lead halides and the CH3NH3+ organic cation is known to yield the CH3NH3PbI3 perovskite structure upon annealing. In examining the precursor solution used in the processing of CH3NH3PbI3 solar cells, we find that Pb2+ readily forms plumbate complexes in the presence of excess iodide ions and exhibits characteristic absorption bands at 370 (PbI3-) and 425 nm (PbI42-). Through comparative spectral analysis of the absorption features of charge transfer complexes in the solution phase and the final solid-state perovskite films, we are able to fully classify the absorption features in the excited state of CH3NH3PbI3 across the transient absorption spectrum recorded following laser pulse excitation. In particular, we attribute the broad photoinduced absorption to a charge-transfer excited state, and show correlation between the photoinduced absorption and 480 nm bleach signals. These observations lead us to propose a band structure composed of two distinct transitions that is consistent with the various spectral features and kinetic behavior of the CH3NH3PbI3 excited state. Characterization of this unique dual excited state nature provides further insight into the optoelectronic behavior of hybrid lead halide perovskite films and thus aids in elucidating their exceptional photovoltaic properties.

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Friday, October 31, 2014Posted by Jeff Christians

Kamat Lab Papers Make Most Read Lists

The past year has been an exciting and productive time in the Kamat Lab! Below are 7 articles that currently feature among the Most Read Articles in their respective journals over the past 12 months. Congratulations to all of the various authors who have contributed to this exciting work!

467. Band Filling with Free Charge Carriers in Organometal Halide Perovskites
Manser, J. S.; Kamat, P. V. Nat. Photon. 2014, 8, 737–743.

458. Quantum Dot Solar Cells. Hole Transfer as a Limiting Factor in Boosting Photoconversion Efficiency
Kamat, P. V.; Christians, J. A.; Radich, J. G. Langmuir 30 (20), 5716-5725 (Feature Article).

454. Recent Advances in Quantum Dot Surface Chemistry
Hines, D. A.; Kamat, P. V. ACS Appl. Mater. Interfaces 2014, 6 (5), 3041–3057.

449. An Inorganic Hole Conductor for Organo-Lead Halide Perovskite Solar Cells. Improved Hole Conductivity with Copper Iodide
Christians, J. A.; Fung, R. C. A.; Kamat, P. V. J. Am. Chem. Soc. 2014, 136 (2), 758-764.

438. Quantum Dot Solar Cells. The Next Big Thing in Photovoltaics.
Kamat, P. V. J. Phys. Chem. Lett. 2013, 4, 908–918.

374. Quantum Dot Solar Cells. Semiconductor Nanocrystals as Light Harvestors - Centennial Feature Article
Kamat, P. V. J. Phys. Chem. C 2008, 112, 18737-18753 . NDRL 4770

353. Meeting the Clean Energy Demand: Nanostructure Architectures for Solar Energy Conversion.
Kamat, P. V. J. Phys. Chem. C 2007, 111, 2834-2860. (Feature Article in February 22 2007 issue) NDRL 4697

All Publications

Tuesday, October 28, 2014Posted by Jeff Christians

Editorial: Mastering the Art of Scientific Publication

"As new researchers generate their first results, they face the challenge of mastering the art of scientific publication in order to present their results and to draw attention to their new scientific findings. Whether or not we want to describe science in such terms, scientific publishing is competitive in nature, and thus younger scientists must vie with their more experienced peers for recognition. While the electronic age has made the publication process easier and quicker, optimizing the structure of a scientific paper requires a certain degree of skill and proficiency.(1) ACS Publications has been actively engaged in disseminating the basics of publication through Publication 101 videos and editorials and, in continuation of this spirit, we have assembled this virtual issue (http://pubs.acs.org/page/vi/art_of_scientific_publication.html). This issue draws together, in one place, these editorials that summarize the key steps involved in writing an effective paper, journal submission, review processes, and postpublication efforts. The twenty editorials assembled for this virtual issue provide further details on each of these topics. These topics may also be useful as part of the curriculum for the training of students and young researchers in any academic department."

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