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.
Organisations
Publications
Dunbar AD
(2010)
A solution concentration dependent transition from self-stratification to lateral phase separation in spin-cast PS:d-PMMA thin films.
in The European physical journal. E, Soft matter
Wang T
(2010)
The development of nanoscale morphology in polymer:fullerene photovoltaic blends during solvent casting
in Soft Matter
Pearson AJ
(2013)
The role of dynamic measurements in correlating structure with optoelectronic properties in polymer : fullerene bulk-heterojunction solar cells.
in Reports on progress in physics. Physical Society (Great Britain)
Watters D
(2012)
Optimising the efficiency of carbazole co-polymer solar-cells by control over the metal cathode electrode
in Organic Electronics
Pearson AJ
(2011)
Imaging the bulk nanoscale morphology of organic solar cell blends using helium ion microscopy.
in Nano letters
Pearson A
(2012)
Rationalizing Phase Transitions with Thermal Annealing Temperatures for P3HT:PCBM Organic Photovoltaic Devices
in Macromolecules
Hopkinson P
(2011)
A Phase Diagram of the P3HT:PCBM Organic Photovoltaic System: Implications for Device Processing and Performance
in Macromolecules
Parnell AJ
(2010)
Depletion of PCBM at the cathode interface in P3HT/PCBM thin films as quantified via neutron reflectivity measurements.
in Advanced materials (Deerfield Beach, Fla.)
Wang T
(2011)
Evolution of Structure, Optoelectronic Properties, and Device Performance of Polythiophene:Fullerene Solar Cells During Thermal Annealing
in Advanced Functional Materials
Wang T
(2012)
Correlating Structure with Function in Thermally Annealed PCDTBT:PC 70 BM Photovoltaic Blends
in Advanced Functional 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 | Public |
Country | United Kingdom |
Start |
Company Name | Ossila |
Description | Ossila manufactures equipment, electronics and products for constructing research devices such as graphene and perovskite. |
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 |