Development of supramolecular dyes with application in optoelectronics

LUIS OTERO; MIGUEL GERVALDO; JAVIER DURANTINI; MARISA SANTO; LORENA MACOR; GABRIELA MARZARI; LUCIANA FERNANDEZ; EDGARDO N. DURANTINI; DANIEL HEREDIA; FERNANDO FUNGO; KEN-TSUNG WONG; EVA M. BAREA; JUAN BISQUERT; THOMAS DITTRICH

Cartagena

Simposio; Nanotecnología para Energías en Latinoamérica.; 2012

The development of new organic materials with applications in electro-optical devices is one of the most active fields of research in the last years. The continuous growing of worldwide requirements of environmental friendly energy sources has led to a greater increment in the research for new solar energy conversion devices. In this frame, dyesensitized solar cells (DSSCs) are one of great research interested systems all around the world. A crucial issue in DSSC design is the used dye. Until now, Ru(II) polypyridyl complexes still dominated the most successful systems. However, the limited availability and environmental issues could limit the extensive applications of Ru-based DSSCs. Furthermore, Ru-based dyes are expensive and hard to purify as compared to organic sensitizers. Thus, the search of new highly efficient dyes is one of the most active research subjects in DSSCs development. Organic dyes exhibit many advantages, such as the huge diversity of molecular structures and the possibility of obtaining materials at relatively low cost. Moreover, organic dyes normally exhibit high molar extinction coefficients as compared to those of Ru dyes (< 20 000 M-1 cm-1), allowing to use thinner nano-structured oxide semiconductor films with comparable lightharvesting efficiency, a key factor in solid-state DSSC development. (1-3) On the other hand, the use of organic polymers in electronic and optoelectronic holds the advantages to obtain large area flexible devices, replacing rigid Si and glass substrates. It is expected that the use of polymers will introduce a significantly advance in the construction and application of devices for energy generation, image display, lighting systems and others. The improvement and application of flexible devices are directly associated to the development of new suitable materials and deposition processes. At present two major approaches are used to deposit optoelectronic organic materials layers: thermal evaporation and solution processing. Although thermal evaporation through the use of mask can produce well-ordered patterned films, the throughput is slow and involves expensive vacuum systems. Also, thermal evaporation demands materials with sublimation capability and excellent thermal stability, properties that are not easy to obtain in polymers. Furthermore, low-cost solution processes, as spin coating, deep coating and drop coating, usually produce nonpatterned films that cover the entire substrate. A promising technique for conducting polymer film production is the electropolymerization of electroactive monomers. The polymer films made through this way is an alternative and attractive film formation method to build highly efficient optoelectronic devices. The formation and characterization of a series of polymer films with optoelectronic properties obtained by electropolymerization will be showed. Polymers containing porphyrins, a powerful optical and redox active center, were synthesized and analyzed in our laboratory. Likewise, polymers with electron donor-acceptor moieties, linked by fluorene centre were developed and applied in electro-optical devices. (4-6)