Stretchable N-Type High-Performance Polymers Based on Asymmetric Thienylvinyl-1,1-Dicyanomethylene-3-Indanone for Plastic Electronics

The development of new electron-accepting building blocks to construct high-performance n-type semiconducting polymers is essential for various organic optoelectronic devices. Herein, we have incorporated a newly formulated thienylvinyl-1,1-dicyanomethylene-3-indanone (TIC) electron-accepting monomer into a series of n-type low-band gap polymers alongside cyclopentadithiophene (CDT) and indacenodithiophene (IDT) comonomers. Controlling the regioregularity of the asymmetric TIC has produced regioisomeric polymer structures [semi-regioregular (s-PCDT-TIC and s-PIDT-TIC) and regiorandom (r-PCDT-TIC and r-PIDT-TIC)]. We conducted comparative studies for the regiochemistry control and CDT versus IDT repeating units: (i) The CDT-containing polymers have red-shifted absorption and higher absorptivity compared to the IDT-containing analogues. (ii) The varied regioregularity affects the optical features rather than the energy levels. (iii) All the polymers show excellent n-channel field-effect transistors, with electron mobility higher than 1.0 × 10–2 cm2 V–1 s–1, despite their low-ordered crystallinity. (iv) Stretchable transistors with polymers can achieve high retention of electron mobilities under the external strain; specially, r-PCDT-TIC maintains 95% initial mobility at 100% strain. In addition, an n-type near-infrared organic phototransistor based on s-PCDT-TIC exhibits an excellent photoresponsivity, photodetectivity, and external quantum efficiency of 203 A W–1, 8.1 × 1012 Jones, and 2.42 × 104%, respectively, at a wavelength of 838 nm.