The PHaSE energy center carries out fundamental photovoltaic-oriented research using organic-based polymers and related materials to maximize efficiency in the collection and harvesting of energy over a broad frequency range of the solar spectrum. The center’s strongly-networked, interdisciplinary teams of researchers seek ways to minimize charge-quenching exciton recombination, to maximize electron transport across inorganic/organic interfaces, and to optimize design and fabrication strategies for making inexpensive photovoltaic devices.
A PHaSE research team from Emrick and Russell groups, working with Facilities Director Volodimyr Duzhko, described a major advance in the premier journal Science, which addresses problems of charge transport, open-circuit voltage limitations, and electrode stability at organic-metal interfaces in polymer/organic based solar cells. Emrick group member Zak Page made functionalized fullerenoid compounds that were tested for inherent electron transport behavior in work with Prof. Duzhko. These materials were incorporated into organic solar cells by Russell group postdoctoral associate Yao Liu, as a thin electron selective interlayer (down to 5 nm!, see figure right) between the cathode and the conjugated polymer photoconversion blended material layer. The resulting devices, in some configurations, gave among the highest single junction power conversion efficiencies that have been reported in the literature (nearly 10%). As Prof. Emrick stated in a UMass Amherst news release, “This is really a sweeping change in our ability to move electrons across dissimilar materials."
A major PHaSE research thrust team led by the Venkataraman group with the Lahti and Russell groups published a milestone paper in the ACS journal Nano Letters, "Multiscale Active Layer Morphologies for Organic Photovoltaics Through Self-Assembly of Nanospheres". The article reports making organic photovoltaics by making a bulk heterojunction electroactive layer using organic nanoparticles, which were pre-assembled using an ecologically low impact, water-based process. Lead authors Tim Gehan and Monojit Bag are shown at left, working at the PHaSE Photovoltaic Facility. For more information, see the UMass new office release, which has been reported and linked from the DOE Science Headlines webpage (as of 13 Aug 2014). Listen to DV discuss the work on the WHMP Bill Newman radio show, starting at 20.00 min of the 8-27-14 podcast.
Recent UMass Amherst Polymer Science and Engineering Ph.D. graduate Feng Liu (PHaSE member in Russell and Briseno groups) has been named a recipient of a prestigious 2014 Chinese Government Award for Outstanding Students Abroad. The award consists of a cash prize and a certificate noting the outstanding academic achievements of the recipient, which in Feng's case has included numerous high impact studies relating morphology to organic photovoltaic device performance. Feng will be honored at a May 9 reception at the Chinese Consulate General's residence in New York City. Congratulations to Feng for this recognition of his super work as a PHaSE scientist!
UMass Amherst Ph.D. candidate Timothy Gehan (PHaSE member in Venkataraman and Lahti groups) has been named a recipient of a prestigious Eugene M. Isenberg Award for Spring 2014. He works on assembling organic semiconducting organic polymers into nanoparticles with controlled size and size distribution. Tim's fellowship provides opportunities to work with a private sector mentor to learn how fundamental research in materials chemistry reaches the real world marketplace. Congratulations to Tim for this recognition of his super work as a PHaSE scientist!
University of Massachusetts President Robert L. Caret has announced commercialization grants from the Commercial Ventures and Intellectual Property (CVIP) Technology Development Fund. One of these went to PHaSE ERG 2 coordinator Dhandapani Venkataraman for his proposal, "Organic Photovoltaic Devices Based on Water-based Nanoparticle Dispersions". DV and his group have fabricated organic photovoltaic devices from aqueous dispersions of polymer nanoparticles. The method replaces aromatic solvents in the current fabrication processes with water. The funding will be used to fabricate prototype flexible organic photovoltaic cells from these dispersions. [read more]
The false color enhanced micrograph to the left shows yarn-like clusters of nanoparticles composed of the fullerene derivative PCBM, fabricated by the Venkataraman group in PHaSE. Nanoparticles composed of organic semiconductors like PCBMs are important components in recent PHaSE work aimed at devising readily used, environmentally gentle, methods for making organic photovoltaic active layers with controlled morphology for better photoconversion. [read more]
PHaSE Energy Research Group 1 co-ordinator Todd Emrick from the Department of Polymer Science & Engineering has been named a fellow of the National Academy of Inventors. His group's PHaSE work includes studies of inorganic-organic composite materials for energy transfer and charge transport, and interlayer materials for tuning electrode work functions in solar cells. [read more]
PHaSE work was highlighted in a report at UMass Amherst's Research Next, "Advancing the frontiers of polymer-based photovoltaic research."(Picture credit Amanda Drane UMass '12) [read more]
In joint work, graduate students Feng Liu and Zak Page working with PHaSE senior investigators Todd Emrick, Tom Russell, and Volodimyr Duzhko showed how conjugated polymer zwitterions (CPZs) can be used as interlayers to reduce the work function of the cathode in bulk heterojunction type organic photovoltaic devices. [read more]
PHaSE member Ryan Hayward from the Department of Polymer Science & Engineering has received the 2014 John H. Dillon Medal from the American Physical Society, "for remarkably innovative and creative approaches to the design, realization, and analysis of responsive polymer gels and self-assembled systems". His work with PHaSE has given much insight into polymer and polymer-nanoparticle assembly of electro-active materials. [read more]
Joint work between the Venkataraman, Russell, and Lahti groups has shown that P3HT polymer nanoparticles made with high levels of size control can be "spray painted" into films that transport photo-generated charge as effectively as pristine P3HT spin coated films. This work has great potential for generalization to allow other polymers to be "pre-fabricated" into nanoparticles that can similarly be fabricated, using environmentally friendly, water-based coating techniques. The work was selected as the cover article in its issue of Advanced Materials. [read more]
PHaSE supported work by Ya Liu and Anna Balazs at University of Pittsburgh on designing photoresponsive polymer blends was recently featured on the cover of Langmuir. The work shows a photo-illlumination method to assemble polymers into regular, periodic order (an important goal for photovoltaic design). [read more]
Joint work by Akshay Kokil and senior investigator Jayant Kumar at UMass Lowell, with Paul Homnick and Matt Chudomel of the Lahti group at UMass Amherst, describes a new means to increase photovoltaic conversion efficiencies in Graetzel-type dye-sensitized solar cells (DSSCs), by using small molecule "push-pull" amines as additives in a redox recharge solution. [read more]
PHaSE Energy Research Group 3 co-coordinator Mike Barnes from the Department of Chemistry has been named the 2014 John Burlew Award winner from the American Chemical Society's Connecticut Valley section. The award recognizes Mike's contributions in the areas of single molecule spectroscopy. Mike also plays a leadership role in PHaSE's nanoparticle and condensed phase photophysics and spectro-structural investigations. [read more]