Organic and Organometallic Fluorinated Materials for Electronics and Optoelectronics: A Survey on Recent Research

Conjugated organic polymers, small molecules, and transition metal organometallic complexes are used as active semiconducting materials in electronic and optoelectronic devices including organic solar cells (OSCs), organic field effect transistors (OFETS), organic light emitting diodes (OLEDs). While some of these technologies are mature and already available on the market, research is still very active in academic and industrial laboratories to gain better performances. Major drawbacks which still limit large industrial production of some of these devices are not only the non-optimized performances, but also stability issues and cost. In fact, wide applicability of organic electronic technology largely relies on the development of efficient, durable and cost-effective materials. Properties of molecular and polymeric semiconductors can be properly engineered and finely tuned by the design of the conjugated molecular structure and the selective introduction of various functional groups as substituents. Selective functionalization of the conjugated backbone with fluorine atoms and fluorinated substituents has been largely demonstrated to be an effective structural modification not only for tuning optoelectronic properties, but also to affect solid state organization and to improve stability. This review covers the most important classes of materials (conjugated polymers, small molecules, and organometallic complexes) reporting for each of these classes the applications in OSCs, OFETs, and OLEDs and highlighting the role of fluorine functionalization on the properties. The literature shows intriguing results that can be achieved by fluorine functionalization, and it also points out that this research field is still promising for future progress.