Scientists from Virginia Commonwealth University, Pennsylvania State University and the University of California, Los Angeles have discovered that understanding light absorption (band gap energy) is essential to developing principles for the creation of new materials. From the July 3, 2013 news item on Nanowerk (Note: A link has been removed),

Now, thanks to the work of a team of scientists from Virginia Commonwealth University, Pennsylvania State University and the University of California, Los Angeles, material scientists will have greater insight into the organizing principles that allow for the design of nanoscopic materials with specific band gap energy (“Controlling the Band Gap Energy of Cluster-Assembled Materials”). Band gap energy refers to the minimum energy of light that the material may absorb.

The July 2, 2013 Virginia Commonwealth University news release by Sathya Achia Abraham, which originated the news item, explains the work in more detail (Note: Links have been removed),

Cluster-assembled materials are solids that are constructed from clusters – small nanoparticles of a few to a few dozen atoms. By fabricating these materials with different links, the assembly can be made into separated clusters, chains of clusters, sheets of clusters and three-dimensional lattices of clusters. By changing these linkers, the lowest energy color of light the material can absorb may be changed from deep in the infrared to green.

This research explains how the linkers interact with the cluster and what determines the color of the material.

“The findings help fulfill the ultimate dream in material science, namely, the ability to synthesize novel materials that did not already exist in nature that can perform functions to satisfy our growing needs,” said lead investigator Shiv N. Khanna, Ph.D., professor in the Department of Physics in the VCU College of Humanities and Sciences.

According to Khanna, developing a material with the appropriate band gap that will absorb multiple wavelengths will maximize the efficiency at which the solar energy can be absorbed. Sunlight covers a wide range of wavelengths with the maximum energy wavelength of about 4950 Å.

“The principles developed through the current study offer a general approach for the synthesis of materials with controllable functionalities,” said Arthur Reber, Ph.D., research associate professor in the VCU Department of Physics, who collaborated on the study with Khanna.

“As an example, we have just shown how novel magnetic solids can be synthesized by assembling chosen nanoparticles. These solids have potential applications in motors, generators and other devices critical to energy needs,” said Khanna.

The team is now further developing their ideas to demonstrate applications in optical, catalytic and magnetic materials.

For the curious, here’s a link to and a citation for the research paper,

Controlling the Band Gap Energy of Cluster-Assembled Materials by Sukhendu Mandal, Arthur C. Reber, Meichun Qian, Paul S. Weiss, Shiv N. Khanna, and Ayusman Sen. Acc. Chem. Res., Article ASAP DOI: 10.1021/ar3002975 Publication Date (Web): June 4, 2013
Copyright © 2013 American Chemical Society

This paper is behind a paywall. The scientists have provided an image that illustrates the notion of the clusters and their band gap energy,

Cluster assembled materials with zero to three dimensional architectures, and the background color corresponds to the band gap energy of the material. The center graph shows the band gap energy of 23 cluster assembled materials synthesized in the study with the color corresponding to the band gap energy of the material. Image courtesy of Arthur Reber Ph.D./VCU. [downloaded from http://www.news.vcu.edu/news/Material_Scientists_Reveal_Organizing_Principles_for_Design_of]