Upscaling organic PV

Solution processed organic solar cells are attracting extensive interest as a next generation PV technology. They are promising alternatives to conventional silicon PV's due to their compatibility with high throughput, low CAPEX print-based manufacturing, ease of product integration, flexibility, low weight and ability to operate in outdoor and indoor lighting conditions. They are under development initially for applications ranging from indoor energy harvesting to off-grid charging of for example lighting in developing countries (displacing dangerous and environmentally damaging kerosene lamps), with the longer term aim of building integrated PV applications.

Organic solar cells have undergone significant improvements in their performance with their efficiencies increasing from <3% to >12% in the past decade, achieving the threshold for commercial viability. This improvement has been primarily driven by advances in the donor material design, with the relatively high cost fullerene derivative PCBM the most dominant accepter material. Very recently, the emergence of a range of novel non-fullerene accepter materials has led further breakthroughs in the development of solution processed organic solar cells. Compared to their fullerene-based counterpart, these materials show great promise in achieving superior device performance and lifetimes with significantly reduce device fabrication cost.

Project Aims:
The main aim of this EngD studentship is to identify and address major challenges toward the commercialisation of low cost, efficient and stable solution processed non-fullerene based organic solar cells, aiming for both high quality scientific publications and industrial exploitation. Working closely with academic and industrial partners including in particular Eight19 Ltd and Imperial College London, this studentship will address the following broad research topics. Specific priorities and objectives will be agreed annually in discussion with Eight19 and reviewed at project progress meetings.

Stability. The typically limited operating lifetimes have been identified as a major challenge for the commercialisation of solution processed organic solar cells, with fullerene-induced instability of particular concern. The use of non-fullerene accepters instead of fullerenes in organic solar cells creates further opportunities toward addressing the stability challenge of organic solar cells, with for example, numerous studies already reporting superior lifetimes under ambient exposure or thermal stress conditions. This research topic will include identifying the degradation mechanisms of different types of non-fullerene accepters, in combination with a range of donor materials, understanding how this relates to device performance under real operating conditions, advanced device stability testing under controlled (isolated+mixed) environmental conditions, as well as developing devices with improved operating stability.

Processing. The commercialisation of solution processed organic solar cells requires large area processing methods such as roll-coating and screen printing. A key requirement for such processing methods is the ability to achieve relatively high film thicknesses (from sub-micron to micron) in order to overcome the typically rough substrate interfaces and eliminate film defects, yet without compromising device performance. This research topic will focus on investigating the impact of film thickness upon device operations and identifying potential limiting factors, for thick devices from both materials and devices levels, as well as understanding how this thickness dependence relates to the performance of solution processed non-fullerene based organic solar cells under operating conditions.

Applications. Solution processed organic solar cells have extraordinary potential for low light level PV applications compared to conventional silicon based PV technologies...

The COATED2 CDT will support the aims of the EPSRC/TSB SPECIFIC IKC and the EPSRC CIM in Large Area Electronics at Swansea University through the provision of 40 research engineers (REs). The SPECIFIC IKC has ambitious targets to create buildings that are power-stations through the use of functional coatings. The targets include:

- A £1billion UK manufacturing sector creating business opportunities with export potential
- Creation of around 7,000 manufacturing/construction sector jobs
- Generation of up to 1/3 of the UK's renewable energy target
- Reduction in CO2 emissions of up to 6 million tons

The CIM in Large Area Electronics has key aims that are synergistic with the IKC, in particular to address the challenges of low-cost manufacturing of multi-functional LAE systems and to support the scale-up of technologies for functional materials. Both projects have shared technologies and processes and RE support through COATED2 will have significant impact on achieving their aims through:
- The supply of highly trained and enthusiastic REs for a growing new industry base
- Encouraging radical thinking for REs in terms of optimisation and up-scaling of laboratory concepts to an industrial scale
- Achieving greater engagement with new and existing industry and academic partners.

The COATED2 RE cohorts will provide impact in a number of key areas -

Knowledge
- Research projects defined by industry with a real scientific or engineering need at their core ensuring relevant research is embedded within the industrial partner/University.
- Engagement of multiple partners through the CDT/IKC's open innovation arrangements permits sharing of knowledge between otherwise discrete industries
- Each RE will produce 3 publications and attend 1 international conference disseminating knowledge into the academic community.
- RE research will be evidenced in taught modules ensuring that quality of training is enhanced year on year.
- Development of new technologies will create a lead for the UK in up-scaling of complex functional coated products.
- Training modules are accessible to Industrial partners providing knowledge beyond the scope of the core CDT.

Economy
- Future industry leaders will be created from the CDT. 96% of previous REs at Swansea have moved onto industry related careers.
- Innovative new products and processes will catalyse new industries and technology advances in established manufacturers generating wealth.
- 8 Patents have been filed by the IKC since 2011 and REs are critical for the on-going development of IP exploitation.
- SPECIFIC Innovations has been established to develop business models and spin-out companies for the exploitation of IP created through the CDT and IKC attracting inward investment.
- The facilities within SPECIFIC and the CIM coupled with extensive industrial partners bridges the gap between research and wealth creation ensuring that outputs from the CDT are maximised.

Society
- REs will engage in active outreach to promote their research and attract more people into STEM activities.
- There have been over 1000 separate visits to the IKC/CDT raising awareness of the product potential to a range of end users.
- Research activity at the CDT supporting the IKC and the CIM will contribute towards alleviating fuel poverty, reducing CO2 output and providing energy security
- Water purification, bio-inspired coatings and durability research benefits developed and developing nations.

People
- The CDT will produce 40 highly skilled individuals trained to support industry and academia
- Graduates of the scheme moving into employment will grow networks between academia and industrial partners creating new opportunities for the CDT.
- Shared seminars with other institutions will enable REs to gain insights into complementary research and raise awareness of available facilities and resources