Bilateral Cooperation Romania – Slovenia no. 403/2010

 

            Project title: Optoelectronic Properties of Third Generation Flexible Organic Photovoltaic Cells Based on Conjugated Polymers

            Project costs: 14400 lei

            Project time: 19 months

            Project Coordinating: University of Bucharest

            Project Director: Ph.D. Professor Stefan Antohe

            Contact: tel. +4021 457 45 35

                            fax. +4021 457 44 18

                            e-mail. santohe@solid.fizica.unibuc.ro

 

            Project Summary:

            Solar cells based on inorganic semiconductors belonging to First Generation show a photovoltaic response due to the separation of the photogenerated charge carriers into the internal electric field present in a Schottky barrier. The most important inconvenient of these structures is their relatively high cost generated first of all by the large mass and the energetically processes of crystal growth.

            The solar cells from Second Generation based on thin films overcome in part this inconvenient but their power conversion efficiency is smaller associated with physical properties of thin layers.

            At the beginning of the last decade of the 20^th century an internal power conversion efficiency of 0,7 % was reported by Hiramoto and co-workers for a three-layered organic photovoltaic cells with a co-deposited interlayer between the p-type and n-type layers, which has been found to act as an efficient carrier photogeneration layer into a p-i-n structure.

            As a permanent goal to discover new organic materials for photovoltaic applications, the field of conjugated polymers reached and increased interest. It has been shown that in conjugated polymers doped with C60 molecules a photoinduced electron transfer take place and the photoconductivity increases. These observations led to the development of two-layer cells based on polymer-fullerene and to the concept of bulk heterojunction.

            In this project we plan to expand the experiments to an area of particular importance for the advancement of organic photovoltaic. The experiments will be targeted to elucidate the potential role of individual members of the blend, PCBM and P3HT on the optoelectronic properties of the blend. The characterization will include morphological investigation of organic layer surface prior to evaporation of Al, by atomic force microscopy (AFM) and X-ray diffraction (XRD). Electric transport will be characterized by current-voltage (I-V) measurements and transient photocurrent measurements. For all the structures we will use flexible substrates, PET/ITO.

            Project objectives:

1.      Preparation and structural, morphological, electrical and optical characterization of the P3HT, PCBM and P3HT:PCBM(1:1) thin films deposited by spin-coating technique on flexible and transparent substrates and the analysis of the electrical and optical behavior of the ITO/Polymer and Metal/Polymer interfaces.

2.      Preparation and electrical and optical characterization of the PET/ITO/PEDOT/P3HT or PCBM or P3HT:PCBM(1:1) photovoltaic cells.