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

Todate, the preparation of high-performance stretchable and elasticsemiconductors remains challenging yet urgently demanded by the stretchableelectronics field. Herein, we design a multiblock polyurethane elastomermatrix PBTTT-b-HTPB by incorporating crystallineoligothiophene and flexible polyolefin blocks to blend with conjugatedpolymers for high-mobility semiconductor nanofilms with enhanced stretchabilityand elasticity. The compatibility between the matrix and the conjugatedpolymer is found to play the key role in manipulating the verticaland lateral phase separation structure, hence the electrical and mechanicalperformance of the resulting semiconducting blend films. Though fiverepresentative p-type conjugated polymers (PCDTBT, TDPP-Se, PffBT4T-DT,PBTTT and IDTBT) all form vertical continuous structures, as confirmedby film-depth-dependent light absorption spectra, only the formerfour thermodynamically compatible polymers can generate well-dispersedlateral structures for improved mechanical properties without compromisingelectrical performance. In particular, the mobility of TDPP-Se/PBTTT-b-HTPB (1:3 by weight) nanofilms reaches 2.20 cm(2) V-1 s(-1) in thin-film transistors,which is among the highest values for stretchable semiconductors characterizedby conventional rigid devices so far. In addition, top mechanicalperformance with a fracture strain of 446 & PLUSMN; 35% and an elasticrecovery higher than 90% in the strain range of 100-150% isrealized at the same time. Notably, the excellent elasticity enabledthe nanofilm's long cycling life of up to 5000 cycles at a100% strain, which is by far the longest cycling life at such a largestrain, demonstrating its potential for practical application forwearable electronics.