Large area plastic solar cell modules
Introduction
Polymer photovoltaics [1], [2], [3], [4], [5], [6] is a very promising technology that in principle offers the possibility for the production of solar cells at a fraction of the cost of expensive silicon based semiconductor photovoltaics in high volumes. The production of polymer based photovoltaics using industrial screen printing have demonstrated the possibility of producing on the order of 1000–100,000 m2 on a process line per day. The production of the same solar cell area based on silicon in a state-of-the-art production plant typically takes 1 year. There are however still some shortcomings of organic photovoltaics that need a solution before commercialisation at that level will be possible. The efficiency and especially the lifetimes of polymer photovoltaics are currently low. Efficiencies just below 5% have been reported [7], [8] on very small active areas and while this is getting closer to the range of efficiencies obtained for silicon based solar cells (10–25%) there is still some room for improvement. The module efficiencies for commercial silicon solar cells are in the 10–20% range and data for polymer solar cell module efficiencies are needed. Commonly efficiency data for organic photovoltaics are based on very small solar cells with active areas of few mm2. Research on large area organic/polymer photovoltaics is dawning and research on organic/polymer photovoltaic modules has not been addressed in any great detail. The purpose of this work was to address the problems associated with large area organic/polymer photovoltaics, printing and patterning of the active layer [9], [10], [11] and module preparation. The typical device structure for organic/polymer photovoltaic devices is a multilayer planar geometry with one or more active layers sandwiched between two electrodes. Commonly a substrate carrier bearing one of the electrodes is used for patterning the active layers that may involve a vacuum deposition process. Following on from this the final electrode is applied. Most often the final electrodes are applied in a vacuum coating process by evaporation of a metal like aluminium using thermal or e-beam evaporation. A process line capable of handling large area organic/polymer photovoltaics in a batch process has been designed for these research purposes.
In this paper we demonstrate the production of large area polymer based solar cells and encompass aspects of module design in the context of current polymer photovoltaic materials. We address the problems associated with the connection of many solar cells into a module and demonstrate a 0.1 m2 polymer solar cell module Fig. 1.
Section snippets
Active material
Poly-1,4-(2-methoxy-5-ethylhexyloxy)phenylenevinylene (MEH-PPV) was prepared by the Gilch route [12]. Large amounts were needed for the screen-printing and it was found impractical to use volumes larger than 10 L. Ten batches were prepared each starting from 200 g of monomer. This gave 600 g of crude MEH-PPV. All the batches were combined and dissolved in THF (20 L) by careful mechanical stirring under argon and with the exclusion of light for 48 h. The thick solution was then filtered through glass
Results and discussion
The active layer of polymer based solar cells has mostly been prepared by spincoating, casting or doctor blading and while these techniques are excellent for fundamental studies large area high volume production is anticipated to require different techniques like roll-to-roll coating, spraying or screen-printing. Screen-printing has been employed for the printing of the active layer of polymer photovoltaics in small area [9], [11] and large area [10]. These promising results led us to attempt
Conclusions
The design and fabrication of 0.1 m2 solar cell modules was demonstrated and pertinent issues in relation to interconnection, lifetimes and mechanical stability was detailed. It was found possible to achieve an active area of 65% of the total module area. The efficiencies obtained for the modules were much lower than expected. Possible reasons for this behaviour is believed to be contact problems, atmospheric handling during device preparation and possibly electron radiation damage to the active
Acknowledgements
We would like to thank Niller Fagerberg for technical assistance with the large scale synthesis of MEH-PPV. This work was supported by the Danish Technical Research Council (STVF 26-02-0174, STVF 2058-03-0016), the Danish Strategic Research Council (DSF 2104-04-0030) and Public Service Obligation (PSO 103032 FU 3301).
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2019, Opto-Electronics ReviewGeometrical optimization for high efficiency carbon perovskite modules
2019, Solar EnergyCitation Excerpt :The poor conductivity of the FTO and carbon electrodes limits a further performance improvement for large scale C-PSC modules and requires careful design to overcome. A ‘sub-cell design’ is used with series connection of individual cells to minimise resistance related losses (Krebs et al., 2007). This ‘sub-cell’ design has to maximise the dimensions of the active area and minimizing the dimension of the non-active area, including the interconnection area, whilst still minimizing the resistive losses.