Polycyclic Aromatic Hydrocarbon End Group Integrated Pyridine Flanked Diketopyrrolopyrrole Semiconductors for Organic Field Effect Transistors

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are an interesting class of organic semiconducting material (OSM) due to their notable optoelectronic properties. However, their widespread use in organic electronics is often limited by their poor solubility, vacuum processes, and high cost. Herein, we report two series of PAHs integrated OSMs (DPPPy-C10-AN, DPPPy-C10-FA, and DPPPy-C10-DPB-FA; DPPPy-C-Si-AN, DPPPy-C-Si-FA, and DPPPy-C-Si-DPB-FA) in which alkyl/siloxane-appended pyridine-flanked diketopyrrolopyrrole is π-conjugated to acenaphthene (AN), fluoranthene (FA), and diphenylbenzo-fluoranthene (DPB-FA), respectively. Although both series of PAHs integrated OSMs showed sufficient solubility in common organic solvents, the siloxane derivatives exhibited superior solubility compared to the alkyl counterparts. Upon varying the PAHs (from AN to FA and further to DPB-FA) on OSMs, only marginal variations were observed in the optical properties, band gaps, and frontier energy level values. In contrast, GIWAXS results revealed substantial changes in the crystalline properties of thin films. Importantly, AN- and FA-based molecules demonstrated enhanced crystallinity compared to DPB-FA molecules. Furthermore, DPPPy-C-Si-AN:SEBS and DPPPy-C-Si-FA:SEBS stretchable blends showed ordered orientation compared to DPPPy-C10-AN:SEBS and DPPPy-C10-FA:SEBS. DPPPy-C10-DPB-FA:SEBS and DPPPy-C-Si-DPB-FA:SEBS blends exhibited poorer orientation compared to the pristine or other molecules. Organic field-effect transistors based on DPPPy-C-Si-FA displayed the highest electron mobility of 28 × 10–3 cm2 V–1 s–1 among all the molecules and their elastomeric blends.