Synthetic Aspects of Organic Semiconductors
- PDF / 436,822 Bytes
- 8 Pages / 612 x 792 pts (letter) Page_size
- 10 Downloads / 274 Views
through single-carbon linkages [for example, oligothiophene 1 (Scheme 2), containing six linked thiophene rings], and fused aromatics, which are joined together through multiple carbon linkages [for example, pentacene 8 (Scheme 5), containing five fused aromatic rings]. Linked aromatics are generally formed by the coupling of individual aromatic repeat units, whereas fused systems require the construction of the aromatic rings themselves, significantly complicating their preparation.
of Organic Semiconductors
John E. Anthony, Martin Heeney, and Beng S. Ong
Linked Aromatic Systems
Abstract This article discusses the importance of the choice of synthetic methodology in the purity, and therefore performance, of both small-molecule and polymeric organic semiconductors. We discuss common methodologies used in the preparation of organic semiconductors, paying particular attention to the impurities and by-products that can arise during these synthetic approaches and how they can have an impact on semiconductor performance.
Introduction Significant progress in the performance of both small-molecule and polymer organic semiconductors has been realized over the past decade, and commercial applications are beginning to appear. Because of these dramatic advances, a number of comprehensive reviews of the molecular, processing, and device aspects of these materials have been published over the past few years.1–13 However, few recent reviews have covered the chemistry of organic semiconductors. In this article, we consider the critical role of the choice of synthetic methodology in the purity, and therefore performance, of both smallmolecule and polymeric organic semiconductors. Because many synthetic organic chemists are trained in laboratories specializing in the synthesis of natural bioactive materials, it is often a significant leap for them to switch from synthesis of materials of “pharmaceutical purity” to the synthesis of materials of “electronicsgrade” purity. To illustrate the role of synthetic route in determining material purity, we focus on the more common methods used to synthesize both smallmolecule and polymeric organic semiconductor materials, with particular focus on the types of impurities and by-products to be expected from the most common synthetic approaches.
698
Synthetic Aspects of SmallMolecule Organic Semiconductors Organic semiconductors in general are more tolerant of low ( 150 kDa), the high polymer viscosity can hinder crystallization during annealing, resulting in a suboptimal mobility. A systematic study of the influence of polydispersity on charge-carrier mobility has not been reported, but high polydispersity would be expected to reduce the crystallinity of the polymer78 and, therefore, to be detrimental to device performance. Impurities resulting from the synthesis such as catalyst residues can have a deleterious impact on device performance,31,79,80 and although purification is much more complex for polymers than for sublimable small molecules, techniques such as sequestration, washing, o
Data Loading...
