A solution-processed and low threshold voltage p-type small molecule based on indolocarbazole- and benzothiophene-fused rings. (September 2017)

• Record Type: Journal Article
• Authors: Chen, Guiting; Sun, Sheng; Yang, Yong; Lan, Linfeng; Ying, Lei; Yang, Wei; Zhang, Bin; Cao, Yong
• Is Part Of: Dyes and pigments. Volume 144(2017)
• Page Start: 32
• Page End: 40
• Publication Date: 2017-09
• Subjects: Indolocarbazole -- Benzothiophene -- p-type -- Small molecules -- OFETs; Dyes and dyeing -- Periodicals; Pigments -- Periodicals; 667.2
• DOI: 10.1016/j.dyepig.2017.05.019
• Languages: English
• ISSNs: 0143-7208

Abstract

Abstract: A novel planar heteroacene, 8, 17-dihexadecyl-8, 17-dihydrobenzo[4′, 5′]thieno[2′, 3′:5, 6] indolo[3, 2- b ]benzo[4, 5]thieno[2, 3-h]carbazole (ICzDBT), was designed and synthesized. The thermal, optical, electrochemical and field-effect transistor properties were investigated systematically. The highest occupied molecular orbital energy levels ( E HOMO ) measured by cyclic voltammetry and photoelectron yield spectra were −5.15 and −5.29 eV, respectively, which are close to the work function ( WF ) of Au (∼5.2 eV). This suitable energy level alignment between the E HOMO of ICzDBT and WF of Au is favorable for hole carrier injection from the Au electrode to the ICzDBT layer. The ICzDBT showed a hole mobility as high as 0.17 cm 2 V −1 s −1 and a current on/off ratio of 1.2 × 10 6, with a very low threshold voltage of −0.8 V. Moreover, the device displayed excellent stability with little roll-off of hole mobility in air. Hence, this kind of molecule is a promising candidate for p-type organic field-effect transistors (OFETs) with high mobility and air stability. Graphical abstract: Highlights: A novel planar p-type heteroacene (ICzDBT) was designed and synthesized. The field-effect transistor properties show very low threshold voltage of −0.8 V. The ICzDBT displays highly thermal and electric stability.