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Donor–acceptor (D–A) conjugated polymers (CPs) with various D–A pairs have been developed as thermoelectric (TE) materials because of their superior charge-carrier mobilities and Seebeck coefficient values. However, because D–A CPs alter their molecular packing structures through both the doping process and different donor and acceptor moiety chemical structures, the complex structure–property relationships of doped D–A CPs impede the understanding of the influence of the electronic structure on charge transport. Herein, the influence of the electronic structures on the TE properties of five random D–A copolymers were investigated. The diketopyrrolopyrrole-based D–A copolymers were synthesized by varying the feed ratio of two oligomeric building blocks that differed only in the introduction of a strong electron-withdrawing cyano group on the vinylene linkage flanked between two thiophene rings. The almost identical crystalline structures and film morphologies of these D–A copolymers were confirmed, even after doping with FeCl3. The charge-carrier mobility of the doped CPs increased with delocalization of the polarons with an increasing DPP-TVT composition, resulting in a superior TE performance with a maximum power factor of 79.8 μW m−1 K−2. The correlation between the charge-carrier mobilities and TE performance was further investigated using the Kang–Snyder theoretical model. This study provides an understanding of the impact of the electronic structure of donor and acceptor moieties on the TE performance, and offers useful guidelines for the selection of D–A pairs to develop excellent TE materials. [ABSTRACT FROM AUTHOR]

Conjugated polymers based on cyclopentadithiophene (CPDT) moieties are widely used in optoelectronics applications but rarely in field‐effect transistors (FETs). This is due to the steric hindrance at the tetrahedral center of the CPDT core, which is a critical problem requiring resolution without diminishing the polymer crystallinity and solubility. A bulky CPDT‐based high‐mobility copolymers are synthesized here, which shows excellent π–π stacking in the film states with good solubility. The addition of bulky ethylhexyl side chains to CPDT does not interfere with the molecular ordering and promotes the intercalation of linear alkyl chains on the co‐monomeric units. The resulting polymer forms bimodal packing structures with strong lamellar ordering and π–π interactions. Furthermore, the free volume generated by the bulky ethylhexyl side chains allows for a small amount of fullerene additive to be contained in the film state without interfering with the molecular ordering, leading to enhanced on/off ratios and hole mobilities of the resulting FETs. As a result, promising hole mobilities of up to 1.08–1.64 cm2 V−1 s−1 are achieved with the optimized FETs, which are the highest mobilities reported for CPDT‐based conjugated polymers containing branched alkyl side chains. [ABSTRACT FROM AUTHOR]

Self‐healable and stretchable energy‐harvesting materials can provide a new avenue for the realization of self‐powered wearable electronics, including electronic skins, whose main materials are required to be robust to and stable under external damage and severe mechanical stresses. However, thermoelectric (TE) materials showing both self‐healing properties and stretchability have not yet been demonstrated despite their great potential to harvest thermal energy in the human body. As most existing TE materials are either mechanically brittle or unrecoverable after being subjected to damage, a novel approach is necessary for designing such materials. Herein, self‐healable and stretchable TE materials based on all‐organic composite system wherein polymer semiconductor nanowires are p‐doped with a molecular dopant and embedded in a thermoplastic elastomer matrix are reported. The polymer nanowires are electrically percolated in the matrix, and the resulting composite materials exhibit good TE performance. The composites also exhibit both excellent self‐healing properties under mild heat and pressure conditions and good stretchability. It is believed that this work can be a cornerstone for the design of self‐healable and stretchable energy‐harvesting materials as it provides useful guidelines for imparting electrical conductivity to insulating thermoplastic elastomers, which typically possess versatile and useful mechanical properties. [ABSTRACT FROM AUTHOR]

Organic-inorganic hybrid CH 3 NH 3 PbBr 3 (MAPbBr 3 ) perovskite quantum dots (PQDs) are considered as promising and cost-effective building blocks for various optoelectronic devices. However, during centrifugation for the purification of these PQDs, commonly used polar protic and aprotic non-solvents (e.g., methanol and acetone) can destroy the nanocrystal structure of MAPbBr 3 perovskites, which will significantly reduce the production yields and degrade the optical properties of the PQDs. This study demonstrates the use of methyl acetate (MeOAc) as an effective non-solvent for purifying as-synthesized MAPbBr 3 PQDs without causing severe damage, which facilitates attainment of stable PQD solutions with high production yields. The MeOAc-washed MAPbBr 3 PQDs maintain their high photoluminescence (PL) quantum yields and crystalline structures for long periods in solution states. MeOAc undergoes a hydrolysis reaction in the presence of the PQDs, and the resulting acetate anions partially replace the original surface ligands without damaging the PQD cores. Time-resolved PL analysis reveals that the MeOAc-washed PQDs show suppressed non-radiative recombination and a longer PL lifetime than acetone-washed and methanol-washed PQDs. Finally, it is demonstrated that a composite of the MAPbBr 3 PQDs and a thermoplastic elastomer (polystyrene- block -polyisoprene- block -polystyrene) is feasible as a stretchable and self-healable green color filter for a white light-emitting diode device.