Fig. 2: Systematic investigation of molecular design principles of iRUM semiconductors.

The obtained semiconductor film is named ‘iRUM-s-x:y’, in which ‘s’ stands for semiconductor and ‘x:y’ is the BA-to-DPPTT weight ratio. Chemical structures of different polybutadiene-based precursors a BA, b BF, c BAc, d BH, and the generated semiconductor film after blending with DPPTT followed by thermal annealing at 150 ^oC. e The free-standing elastic rubber film created by BA through azide/double bond cycloaddition. f AFM phase image and AFM-IR overlay image of iRUM-s-3:1 film. The surface roughness is obtained from the AFM height image. In the composition map, red color represents the DPPTT phase probed by IR laser at 1660 cm⁻¹ and the green color represents the BA phase probed at 1722 cm⁻¹ respectively. g Screen shot of MD simulated iRUM-s-3:1 film (simulation box length: ~5.8 nm), showing distributions of DPPTT and BA in a blend. h The extracted mobility of iRUM-s-x:y (BA/DPPTT-x:y) films, BF/DPPTT-x:y blend films, BAc/DPPTT-x:y and BH/DPPTT-x:y crosslinked films where x:y is the precursor-to-DPPTT weight ratio, characterized in bottom-gate top-contact transistors using SiO₂ (300 nm)/Si as dielectric and gate electrode. i The representative transfer curves for iRUM-s-3:1 and BH/DPPTT-3:1 films. j UV–vis spectrum for iRUM-s and BH/DPPTT films prior and after thermal crosslinking. k Schematic illustration of the stretching of the semiconductor film on a supported PDMS substrate. Optical microscope images of a neat DPPTT film and an iRUM-s-3:1 film under 100% strain. l The representative stress-strain (engineering) curves for DPPTT and iRUM-s-x:y films obtained from pseudo-free-standing tensile tests^34,35. m The extracted elastic modulus and fracture strain of iRUM-s (BA/DPPTT) films, BF/DPPTT blend films, BAc/DPPTT and BH/DPPTT crosslinked films obtained from pseudo-free-standing tensile tests (the precursor-to-DPPTT weight ratio is 1:1).