A hybrid photovoltaic-piezoelectric device has been developed at the Institute of Material Research and Innovation (IMRI) of the University of Bolton which is capable of generating electrical energy from solar, wind and rain energy.
The research team behind this new device comprises of Prof Elias Siores, Director of IMRI and Director of Research of the University, Dr Tahir Shah, Dr Ravi Hadimani and Miss Derman Vatansever. The team has attracted a number of international grants including EU and international grants and published more than 300 scientific papers in various fields ranging from technical textile to microwave and magnetic materials.
Basic structure
An organic photovoltaic cell based on P3HT and PCBM has been developed on a piezoelectric PVDF polymer substrate. Hybrid films are constructed by depositing an organic photovoltaic cell on a commercial PVDF film whilst hybrid fibres are developed by depositing an organic solar cell on a piezoelectric polymer fibre. When the hybrid film/fibre is subjected to mechanical vibrations from wind, rain or tide the piezoelectric part produces an electrical voltage which is converted to a constant DC voltage by a rectifier. The photovoltaic part of the hybrid film produces constant DC voltage from solar energy. The electrical energy can then either be used online or stored in a battery.
Making a difference
Earlier this year, the team won the 2011 Energy Innovation Award in Manchester, UK. Chief inventor Professor Siores commented: "It is for the first time that a hybrid photovoltaic-piezoelectric film or fibre has been developed. It is also for the first time that a homogenous piezoelectric polymer fibre capable of being woven into fabric has been developed. It is a flexible hybrid system made of fibres for making small and large structures that can harvest the sun, rain, wind and tides and convert it to usable energy."
But how is this new fibre going to be making a difference in the production of sustainable energy? The hybrid photovoltaic-piezoelectric film and fibre have the capacity to produce electrical energy continuously without the dependence on only one renewable energy source such as solar, wind or rain thus, reducing the carbon foot print. The hybrid fibres when knitted or weaved into wearable textiles can generate energy to power personal electronic gadgets and to power communication devices in remote areas. The fibres and films are developed using less expensive non-ITO photovoltaic and lead-free piezoelectric polymer materials enabling more environmentally-friendly devices that can be mass produced at lower prices.
Further development work
The main challenges faced when trying to develop these devices were:
- a. Producing an organic photovoltaic cell outside any controlled atmosphere or special environmental conditions (atmospheric rather than vacuum processing)
- b. Producing devices using environmentally friendly materials (in this case piezoelectrics that are lead-free) and
- c. Avoiding the use of ITO in order to produce the final devices inexpensively.
A further challenge remains though, and it's related to the higher cost of active organic PV materials (such as P3HT and PCBM) as these materials are still produced at low volumes.
When asked what the further development directions are that the team is following in order to improve the performance of these new devices, Professor Siores said: "We are currently working on improving the efficiency of the organic photovoltaic part of the hybrid cell by incorporating carbon nanotubes (CNT) to improve the transportation of electrons to the electrodes with which we can make thicker cells which can produce higher currents. In addition we are working on the development of piezoelectric materials through fundamental chemistry. Furthermore, conversion optimisation techniques via smart micro-grid technology are being developed to enable better energy yield levels."
Top image shows Professor Siores holding a bundle of the hybrid photovoltaic-piezoelectric fibres
