HYBRID EVENT: You can participate in person at Boston, Massachusetts, USA or Virtually from your home or work.

Arthur J Nozik

Catalysis 2023
Arthur J Nozik, Speaker at Chemical Engineering Conferences
University of Colorado, United States
Title : Advanced concepts for ultra- high conversion efficiency of solar photons into photovoltaics and solar fuels based on quantization effects in nanostructures and molecular singlet fission


In order to utilize solar power for the production of solar electricity and solar fuels on a global scale, it will be necessary to develop solar photon conversion systems that have an appropriate combination of high efficiency (delivered watts/m2) and low capital cost ($/m2).  One potential, long-term approach to attain high conversion efficiencies above (by a factor of 2) the well-known Shockley-Queisser thermodynamic limit of 33% is to utilize the unique properties of quantum dot/rod (QD/QR) nanostructures and Singlet Fission (SF) in molecular chromophores, to control the relaxation dynamics of photogenerated hot carriers and excited states in photoexcited molecules to produce either enhanced photocurrent through efficient photogenerated electron-hole pair (ie, exciton) multiplication or enhanced photopotential through hot electron transport and transfer processes.  To achieve these desirable effects it is necessary to understand and control the dynamics of SF and hot electron and hole cooling, charge transport, and interfacial charge transfer of the photogenerated carriers. These fundamental dynamics in various bulk and quantized nanoscale semiconductors and SF molecules have been studied for many years using various spectroscopies with fs to ns time resolution. The prediction that the generation of more than one electron-hole pair (which exist as excitons in size-quantized nanostructures and photoexcited molecules) per absorbed photon would be an efficient process in QDs,QRs and SF molecules,  has been confirmed over the past years in different classes of materials, molecules, and in their device architectures.  Very efficient and ultrafast  multiple exciton generation (MEG), also called Carrier Multiplication (CM), and SF from absorbed single higher energy photons has been reported in many quantized semiconductors and molecules and associated solar photon conversion devices for solar electricity and solar fuels (e.g. H2) production. Selected aspects of this work will be summarized and recent advances will be discussed, including the very remarkable and extremely large beneficial theoretical effects obtain when combining MEG with solar concentration. The analogous MEG effect in SF molecules and its use in molecular-based solar cells  will also be discussed. 


Dr. Nozik has established a leading position in the interdisciplinary fields of photoelectrochemistry, semiconductor-molecule interfaces, quantum size effects and electron relaxation dynamics in semiconductor quantum wells, quantum dots,quantum wires, and nanostructures, and applications of this science to solar photon conversion technologies. He has published over 270 peer reviewed papers, proceedings, and book chapters in these fields and in the related fields of photocatalysis, heterogeneous catalysis, the optical, magnetic and electrical properties of solids, and Mössbauer spectroscopy, and has presented > 380 invited talks. He has led a large group of scientists engaged in basic and applied research on the direct photoconversion of light into chemicals, fuels and electricity, and on the optical and electronic properties and applications of nanostructures. Dr. Nozik has been awarded 11 U.S. patents and has received many honors and awards