Project Acronym DUC3PV
Project Title Disposable ultra-cheap printed paper photovoltaics
Project Start Date 01/03/2013
Project Duration 24 Months
Project Website http://duc.pppv.de
Partners’ names and countries Technische Universität Chemnitz (PMTUC), Germany
Johannes Kepler Universität Linz (LIOS), Austria
Institute of Organic Chemistry, Polish Academy of Science (IOC PAS), Poland
ALTANA AG, Germany

Project Coordinator:

Name: Arved Carl Hübler

Organization: Technische Universität Chemnitz

E-mail: pmhuebler@mb.tu-chemnitz.de

The main project idea of DUC3PV is the design and synthesis of dyes, which possess, in addition to basic properties, also the ability to be transformed into flat, non-soluble analogues. That is strongly related to the efficiency of the charge transfer, usually supported by π-π-stacking interactions between the molecules. Moreover, the capability to form self-organized structures will strengthen this phenomenon.

These materials should be integrated into the new developed printable solar cell stack on paper substrate ((3PV). Therefore the performance of the 3PVV-stack should be investigated and the efficiency of the electrode contact should be enhanced with the help of standard polymeric semiconductors. In a following step the transfer of the enhanced polymeric 3PVV-stack to R2R-printinng technology should be investigated. In a last step the new developed dye can be integrated in this R2R printed 3PV-stack.

To enhance the lifetime performance of the new developed solar cell also, in a second track the concept of cheap encapsulation layers are under investigation.

As a first class off materials porphyrinoids were under investigation. At these molecules the desired solubility can be easily achieved by introducing proper aryl-substituents into their mezzo-positions. It was found, that β-alkynyl substituted porphyrins can be transformed with temperature around 200°C which is too high for flexible R2R-Proccessing.

Following the general aim of the proposal, rather than specific structures we studied photo-oxidation of bis-coumarins. This reaction transforms well-soluble compounds into completely flat pentacene analogs. Photo-cyclization undergoes efficiently in solution but reaction in the this films (i.e. in the solid state) is problematic. New derivatives with tailored properties are under way.

To enhance the electrode layers in the 3PPV-solar cell a modifying material was integrated to optimize the workfunction of the cathode layer and enhance the charge transport from active material to the electrode. This material was first test in lab scale and later integrated to R2R-printing process.

To enhance the charge transport efficiency of the transparent top electrode different alternative materials were evaporated and from solution processed. Highest power conversion efficiencies of 4% on paper were shown in lab scale with the semiconductor PTB7:PC770BM and an evaporated MoO3/Ag/MoO3 electrode. Best candidate for liquid processing was a combination layer out of PEDOTT:PSS and Ag-nanowires. This setup has to be integrated to the R2R-printing process..

To show the functionality of the 3PV-solar cell stack a new module design with 8 solar cells in series was created and R2R-printed. With this demonstrator platform a voltage of 4 Volt is available to drive small applications.

To increase the lifetime of thee developed modules a new flexible and cheap encapsulation material out of Aluminium back sheet and transparent front sheet with integrated hot melt glue was developed and produced. Penetration tests did show that the new material achieves all requirements. For encapsulation of 3PV-module the material was applied in a developed vacuum-lamination-process.

This project has successfully enabled the exchange of samples and knowledge between experts in chemical synthesis (PAS), printing technology (PMTUC), organic photovoltaics (LIOS), and PV encapsulation (Isovoltaic). It has produced two joint publications on high efficiency OPV on paper, and on semiconductor properties of small molecules. Our efficiency and encapsulation targets are within reach, though the cost and production throughput goals are still further off. We have reported paper-based solar cells with efficiency over 4%, and expect to report significant improvements in the coming months.