Soft and conformable wearable electronics require stretchable semiconductors, but existing ones typically sacrifice charge transport mobility to achieve stretchability. We explore a concept based on the nanoconfinement of polymers to substantially improve the stretchability of polymer semiconductors, without affecting charge transport mobility. The increased polymer chain dynamics under nanoconfinement significantly reduces the modulus of the conjugated polymer and largely delays the onset of crack formation under strain. As a result, our fabricated semiconducting film can be stretched up to 100% strain without affecting mobility, retaining values comparable to that of amorphous silicon. The fully stretchable transistors exhibit high biaxial stretchability with minimal change in on current even when poked with a sharp object. We demonstrate a skinlike finger-wearable driver for a light-emitting diode.

Stretchable semiconducting polymers have been developed as a key component   to enable skin-like wearable electronics, but their electrical performance must be improved to enable more advanced functionalities. Here, we report a solution processing approach that can achieve multi-scale ordering and alignment of conjugated polymers in stretchable semiconductors to substantially improve their charge carrier mobility. Using solution shearing with a patterned microtrench coating blade, macroscale alignment of conjugated-polymer nanostructures was achieved along the charge transport direction. In conjunction, the nanoscale spatial confinement aligns chain conformation and promotes short-range π-π ordering,   significantly reducing the energetic barrier for charge carrier transport. As a result, the mobilities of stretchable conjugated-polymer films have been enhanced up to threefold and maintained under a strain up to 100%. This method may also serve as the basis for large-area manufacturing of stretchable semiconducting films, as demonstrated by the roll-to-roll coating of metre-scale films.

Poly [2,5-bis(2-decyldodecyl)pyrrolo [3,4-c]pyrrole-1,4(2H,5H)-dione-(E)-1,2-di(2,2 0 -bithiophen-5-yl) ethene] (PDPPDBTE) was successfully incorporated as a p-type hole transporting material in solid-state organicinorganic hybrid solar cells. The excellent optical and electrical properties of organo-lead halide perovskite (CH 3 NH 3 PbI 3 ) nanocrystals used as light harvesters yielded a 9.2% power conversion efficiency (PCE) for the best-performing cell that exceeded the value (7.6%) obtained from the best hole conductor yet reported (2,2 0 ,7,7 0 -tetrakis(N,N-di-p-methoxyphenyl-amine)9,9 0 -spirobifluorene, spiro-MeOTAD). The high PCE was attributed to the optimal oxidation potential (5.4 eV) and excellent charge carrier mobility of the polymer. The hydrophobicity of the polymer prevented water permeation into the porous perovskite heterojunction, and long-term aging tests over 1000 hours confirmed the enhanced stability of the PDPPDBTE-based cells. Broader contextSolid-state organic-inorganic hybrid solar cells have been extensively investigated as an alternative promising energy conversion devices to the conventional silicon-based photovoltaics. With the successful demonstration of the solar cells which utilize lead halide perovskite nanocrystals as excellent light harvesters the overall efficiencies rapidly increased during the last year, yielding over 15% of remarkable performance. Further enhancement of the efficiency could be realized by developing new hole transporting materials with high electrical properties and proper oxidation potential with respect to the energy level of perovskite. To this end, the conjugated polymers are thought to be an alternative to small molecular hole conductors since they have unique charge transport properties with tunable oxidation potential. In this work, we report an efficient stable hybrid solar cells incorporating diketopyrrolopyrrole-containing polymers (PDPPDBTE). With an appropriate oxidation potential of 5.4 eV vs. the vacuum level, the PDPPDBTE conjugated polymer is expected to function efficiently as a hole transporting material. Furthermore, the excellent long-term stability of polymer-based solar cells also guarantee their potential applications.

While high-mobility p-type conjugated polymers have been widely reported, high-mobility n-type conjugated polymers are still rare. In the present work, we designed semifluorinated alkyl side chains and introduced them into naphthalene diimide-based polymers (PNDIF-T2 and PNDIF-TVT). We found that the strong self-organization of these side chains induced a high degree of order in the attached polymer backbones by forming a superstructure composed of "backbone crystals" and "side-chain crystals". This phenomenon was shown to greatly enhance the ordering along the backbone direction, and the resulting polymers thus exhibited unipolar n-channel transport in field-effect transistors with remarkably high electron mobility values of up to 6.50 cm(2) V(-1) s(-1) and with a high on-off current ratio of 10(5).

Systematic side-chain engineering has been performed for diketopyrrolopyrrole-selenophene vinylene selenophene (DPP-SVS) polymers to determine the optimal side-chain geometries for the most efficient charge transport, and the structure-property relationship has been thoroughly investigated using a range of analyses. A series of DPP-SVS polymers, ranging from 25-DPP-SVS to 32-DPP-SVS, with branched alkyl groups containing linear spacer groups from C2 to C9 has been synthesized, and the electrical performance of these polymers is significantly dependent on both the length of the spacer group and its odd-even characteristics. Spacer groups with even numbers of carbon atoms exhibit chargecarrier mobilities that are one order of magnitude higher than those with odd numbers of carbon atoms. The optimized charge transport has been obtained from 29-DPP-SVS with C6 spacer, showing the maximum mobility of 13.9 cm 2 V −1 s −1 (V GS , V DS = −100 V) and 17.8 cm 2 V −1 s −1 (V GS , V DS = −150 V). Longer spacer groups deviate from the odd-even trend. In addition to the exceptionally high charge-carrier mobilities of the DPP-SVS polymers, the results obtained herein provide new insight into the molecular design of high-performance polymer semiconductors.