Optimising polymer photovoltaic devices through control of phase-separation

Lead Research Organisation: University of Sheffield
Department Name: Physics and Astronomy

Abstract

In principle, photovoltaic devices could meet all our energy requirements in a sustainable way, but at the moment the capital expense of conventional photovoltaics is too great to be competitive, and the volume in which they can be produced is much too small to make a serious dent in our electricity generating needs. Their relatively high manufacturing cost and the difficulty of scaling the manufacturing process is an intrinsic feature of their energy-intensive fabrication process. In contrast, non-conventional PVs based on organic semiconductors can be processed from solution using high-volume roll-to-roll printing technologies, offering the possibility of large area devices being fabricated on flexible substrates at very low cost. Unfortunately at present, organic PV devices are characterized by prohibitively low external power efficiencies (< 6%). Closing the gap in efficiency between organic and inorganic PV devices is a significant challenge / one which will require a full microscopic understanding of the processes that currently limit organic PV efficiency. The most promising organic PV devices are currently based on solution-cast blends of conjugated polymers doped with fullerene derivatives. Relatively little is however known regarding the role of the self-assembled nanoscale morphology of such systems on their operational efficiency. In this proposal, we seek to develop a comprehensive mechanistic understanding of the self-assembly processes by which nanoscale structure arises within such PV applicable materials. In particular we propose to study the evolution of nanoscale phase-separation during film casting using X-ray scattering. We will also utilize a range of complementary microscopy techniques ranging from environmental scanning electron microscopy, to time-resolved near field microscopy. The combination of such techniques will permit us to develop a complete picture of film structure from molecular to microscopic length-scales. Our proposed project draws together some of the UK's leading polymer scientists and technologists, with our goal being to significantly advance the understanding of the processes that limit organic PV device performance.

Publications

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Staniec P (2011) The Nanoscale Morphology of a PCDTBT:PCBM Photovoltaic Blend in Advanced Energy Materials

 
Description The work set out to explore a new type of plastic thin-film that has application in solar cell devices. In particular, we were interested in how the structure of the thin at the length-scales associated with individual molecules affected its ability to collect light and generate electricity within the solar cell. As part of this work, we developed new techniques that involved the use of X-rays to follow the evolution of molecular structure within the film as the film dried from a solution. The work helped us understand how structure foams within such films, and ultimately permitted us to make more efficient plastic solar-cell devices.
Exploitation Route The work helps provide important information for other people interested in developing plastic solar cells. The work provides design rules for the development of materials and the ways in which such materials should be processed.
Sectors Chemicals,Electronics,Energy,Manufacturing, including Industrial Biotechology

URL http://www.epmm.group.shef.ac.uk/research/organic-photovoltaics.php
 
Description The information gained during this research has been used to further the development of organic semiconductor thin-films in photovoltaic devices. As part of this research (and via other RCUK projects that ran in parallel), we set up the spin-out company Ossila. This company helped to commercialise the know-how developed within the group and continues to help other researchers working in the same area by accelerating their research through the provision of a range of specially designed consumable items, equipment and materials for optoelectronic technologies.
First Year Of Impact 2009
Sector Chemicals,Electronics,Energy,Manufacturing, including Industrial Biotechology
Impact Types Economic

 
Description EPSRC
Amount £967,004 (GBP)
Funding ID EP/I028641/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start  
 
Company Name Ossila Ltd 
Description The company Ossila Ltd has developed a range of products targeted at developers of organic electronic devices. The company also supplies research-based services to technical markets around the world. The majority of Ossila's sales are through the company website. The company sells a range of laboratory consumable items, electronics and other testing equipment to researchers working in organic electronics. In 75% of cases, the products supplied by Ossila are designed in-house, with the company playing a direct role in their manufacture. Ossila also sells a range of organic semiconductor materials that each come with a full-process recipe that allows the user to fabricate high-efficiency OPV/OLED devices. Ossila commissions the synthesis of many of the organic semiconductors that it sells. Other materials are produced by partner companies and are then re-sold by Ossila; however, considerable value is added through testing material performance, performing quality control and developing processing protocols that are supplied to customers. 
Year Established 2009 
Impact The impact of the company can be judged in terms of the income generated and the jobs created. Ossila provides a catalogue of materials, components and consumable items to researchers working on the development of organic electronic devices, and mainly exports its products to foreign markets (40 countries in total, worldwide). The breakdown of sales per area in 2012 were: UK 15%, EU 36%, US 8%, rest of world 41% (including India, China, Brazil, Korea, Japan, Mexico, Canada, Singapore, Malaysia). Ossila also undertakes contract research projects for other companies and has helped such companies to apply for further funding. Ossila currently employs 17 part-time and full-time workers, and continues to undergo rapid growth and expansion by developing innovative products and materials for thin-film electronics research.
Website http://www.ossila.com/