At Stanford, I worked in the Martínez Group using the Nanoreactor in Terachem to study novel reaction pathways. The ab initio Nanoreactor is a reaction discovery tool that uses GPU acceleration to vastly accelerate the calculation of reaction networks. My efforts involved both the development of the Nanoreactor, by improving and expanding its capabilities, and using the Nanoreactor to understand chemical reaction mechanisms in model systems and systems of industrial interest. In particular, I was interested in better understanding hydrogen combustion, a simple model system that nonetheless exhibits rich and varied chemistry, and perfume discoloration, a challenge with important industrial applications.
Finding the perfect materials for plastic solar cells is one of the grand challenges of modern chemistry. However, studying the materials alone — a major undertaking in its own right — is not enough. In fact, the interface between the different materials in a solar cell plays a major role in determining how much electrical power the cell can output. We searched for the key features of molecular interfaces that enhance the total power output of organic solar cells. In the long run, we hope these discoveries will inspire better devices for widespread solar energy harvesting.
The interface, or contact between the donor and acceptor materials, is a central feature of the organic solar cell. Among its several functions, one of the most important is that it perturbs the energy levels of the bulk materials. Tuning the energy levels at the interface significantly impacts the power generated by the solar cell.
In this research, we studied a model system consisting of a polyhexylthiophene donor material and a perylene diimide acceptor material. We have attempted to construct a reasonable model of the interface as it might be found in actual working conditions, a task complicated by the flexible nature of the materials in question. We hope to use nanoscale smoothing and analysis of interfacial charge and dipolar densities to discover and explore interesting properties of our system.
The results of this research are described in my dissertation: Molecular Modeling of Interfacial Phenomena in Organic Photovoltaics (July 2015).
The Clean Energy Project uses computational chemistry, the support of IBM’s World Community Grid and the willingness of people to help look for the best organic photovoltaics and polymers for applications in inexpensive solar cells. We are also studying how best to assemble the molecules to make those devices. By helping us search combinatorially among thousands of potential systems, you can contribute to this effort.
- Steven A. Lopez, Edward O. Pyzer-Knapp, Gregor N. Simm, Trevor Lutzow, Kewei Li, László R. Seress, Johannes Hachmann, and Alán Aspuru-Guzik. The Harvard organic photovoltaic dataset. Sci. Data, 2016, 3:160086.
- Johannes Hachmann, Roberto Olivares-Amaya, Adrian Jinich, Anthony L. Appleton, Martin A. Blood-Forsythe, László R. Seress, Carolina Román-Salgado, Kai Trepte, Sule Atahan-Evrenk, Süleyman Er, Supriya Shrestha, Rajib Mondal, Anatoliy Sokolov, Zhenan Bao, and Alán Aspuru-Guzik. Lead candidates for high-performance organic photovoltaics from high-throughput quantum chemistry – the Harvard Clean Energy Project. Energy Environ. Sci., 2014, 7, 698-704.
This work was featured on the inside front cover of the journal issue.
- L. R. Seress and T. J. Martínez. Discovering Mechanisms for Perfume Discoloration using ab initio Molecular Dynamics Simulations. Poster presentation. Theory and Application of Computational Chemistry (TACC 2016), Aug 31, 2016.
- L. R. Seress, J. Hachmann, R. Olivares-Amaya, A. Aspuru-Guzik, et al. Lead Candidates for High Performance Photovoltaics: The Harvard Clean Energy Project. Poster presentation. National Collegiate Research Conference (NCRC 2014), Jan 25, 2014.