Elastic Semiconductor Blends with High Strain Cycling Durability Using an Oligothiophene-Based Multiblock Polyurethane Matrix

To date, the preparation of high-performance stretchable and elastic semiconductors remains challenging yet urgently demanded by the stretchable electronics field. Herein, we design a multiblock polyurethane elastomer matrix PBTTT-b-HTPB by incorporating crystalline oligothiophene and flexible polyolefin blocks to blend with conjugated polymers for high-mobility semiconductor nanofilms with enhanced stretchability and elasticity. The compatibility between the matrix and the conjugated polymer is found to play the key role in manipulating the vertical and lateral phase separation structure, hence the electrical and mechanical performance of the resulting semiconducting blend films. Though five representative p-type conjugated polymers (PCDTBT, TDPP-Se, PffBT4T-DT, PBTTT and IDTBT) all form vertical continuous structures, as confirmed by film-depth-dependent light absorption spectra, only the former four thermodynamically compatible polymers can generate well-dispersed lateral structures for improved mechanical properties without compromising electrical performance. In particular, the mobility of TDPP-Se/PBTTT-b-HTPB (1:3 by weight) nanofilms reaches 2.20 cm² V^-1 s^-1 in thin-film transistors, which is among the highest values for stretchable semiconductors characterized by conventional rigid devices so far. In addition, top mechanical performance with a fracture strain of 446 ± 35% and an elastic recovery higher than 90% in the strain range of 100-150% is realized at the same time. Notably, the excellent elasticity enabled the nanofilm’s long cycling life of up to 5000 cycles at a 100% strain, which is by far the longest cycling life at such a large strain, demonstrating its potential for practical application for wearable electronics.