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.

We report six asymmetric alkylated anthracene-based molecules with different alkyl side chain lengths for use in organic field-effect transistors (OFETs). Alkyl side chains can potentially improve the solubility and processability of anthracene derivatives. The crystallinity and charge mobility of the anthracene derivatives may be improved by optimizing the side chain length. The highest field-effect mobility of the devices prepared here was 0.55 cm(2)/(V s), for 2-(p-pentylphenylethynyl)anthracene (PPEA). The moderate side chain length appeared to be optimal for promoting self-organization among asymmetric anthracene derivatives in OFETs, and was certainly better than the short or long alkyl side chain lengths, as confirmed by X-ray diffraction measurements.

High-performance organic nonvolatile memory transistors (ONVMTs) are demonstrated, the construction of which is based on novel integration of a highly conductive polymer as a semiconductor layer, hydroxyl-free polymer as a tunneling dielectric layer, and high-resolution reduced graphene oxide (rGO) patterns as a floating gate. Finely patterned rGO, with a line width of 20-120 μm, was embedded between SiO2 and the polymer dielectric layer, which functions as a nearly isolated charge-trapping center. The resulting ONVMTs demonstrated ideal memory behavior, and the transfer characteristics promptly responded to writing and erasing the gate bias. In particular, the retention time of written/erased states tended to increase as the rGO line width was reduced, implying that the line width is a critical factor in suppressing charge release from rGO. Using a 20-μm-wide rGO pattern, a nonvolatile large memory window (>20 V) was retained for more than 5 × 10(5) s, which is 50 times longer than non-patterned rGO films.

We designed and synthesized a dithienobenzodithiophene-based molecule with a planar molecular geometry, DTBDT-TTPD. It showed low band gap, deep HOMO level and the photovoltaic characteristics included a power conversion efficiency as high as 4.48%.

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