Intrinsically stretchable, electroactive materials featuring self-healing abilities will allow for a variety of nextgeneration stretchable electronics. Here, we synthesize diketopyrrolopyrrole-based "alternating" copolymers with urethane-containing side chains, that is, PDPP urethane copolymers, and use them as active layers in intrinsically stretchable and self-healable plastic transistors. The long-branched urethane side chains possessing moderate H-bonding strength enable sufficient solubility and excellent dynamic bonding, facilitating the stress dissipation under mechanical deformation. PDPP urethane thin films exhibit outstanding stretchability up to 100% external strain without degradation of electrical performance in the organic transistor platform. They also feature self-healing properties with the healing of cracks and the recovery of electrical properties after treatment. The structure−property relationships of PDPP urethane thin films under strain have been thoroughly investigated using a variety of characterization methods. Our results demonstrate a viable approach for the development of stretchable and self-healable plastic electronics using stretchable, semiconducting copolymers obtained via side chain engineering.

Small molecules and oligomers can be synthesized with very high purity and precise molecular weights, but they often do not form uniform thin films while processed from solution. Decreased intermolecular contacts between the small molecules are another disadvantage. To increase the intermolecular contacts in small molecules, we have chosen i-indigo, as one of the conjugated molecular units. The electron poor i-indigo has been connected with electron rich triphenylamine to synthesize a donor-acceptor-donor type small molecule. The propeller shaped triphenylamine helps to increase the solubility of the small molecule as well as isotropic charge transport. The intermolecular spacing between the molecules has been found to be low and did not vary as a function of thermal annealing. This implies that the intermolecular contacts between the small molecules are enhanced, and they do not vary as a function of thermal annealing. Organic field effect transistors (OFET) fabricated using a small molecule exhibited a hole carrier mobility (μ) of 0.3 cm(2)/(V s) before thermal annealing. A marginal increase in μ was observed upon thermal annealing at 150 °C, which has been attributed to changes in thin film morphology. The morphology of the thin films plays an important role in charge transport in addition to the intermolecular spacing that can be modulated with a judicious choice of the conjugated molecular unit.

The novel constitutional isomeric acceptors (o-F-ITIC and m-F-ITIC) are developed and they show the huge disparity of intermolecular interactions and/or arrangements with the donor polymer leading a significant variation in PCE of OSCs.

Metalloporphyrins and metal free porphyrins have been explored as active materials in field effect transistors. Amorphous forms of these porphyrins are preferred over their crystalline analogue due to the ease of solution processability. To achieve solution processability, a metalloporphyrin was anchored on a vinyl polymer by taking advantage of the supramolecular interaction between the metal and the pyridine moiety of the polymer. Non covalent bonding was preferred because it provides an opportunity to better manipulate the polymer's properties compared to its covalent bonding analogue. The binding between the porphyrin and the polymer was optimised in solution and the supramolecular complex was spun on various substrates to form thin films. The porphyrin was found to be uniformly distributed throughout the polymer films contrary to the existing approaches, wherein small molecule phase segregates in the polymer film. Field effect transistors were fabricated using the porphyrinpolymer complex and the device parameters were measured at atmospheric condition. The devices annealed at 80 C showed hole carrier mobility of 2.0 Â 10 À4 cm 2 V À1 s À1 with charge trapping at the dielectric semiconductor interface. Furthermore, the high carrier mobility observed at low temperature annealing makes this supramolecular complex an attractive candidate to explore in flexible substrates.