Naphthobisthiadiazole-Based Selenophene-Incorporated Quarterchalcogenophene Copolymers for Field-Effect Transistors and Polymer Solar Cells

Abstract

In this research, we developed six new selenophene-incorporated naphthobisthiadiazole-based donor−acceptor polymers PNT2Th2Se-OD, PNT2Se2Th-OD, PNT4Se-OD, PNT2Th2Se-DT, PNT2Se2Th-DT, and PNT4Se-DT. The structure−property relationships have been systematically established through the comparison of their structural variations: (1) isomeric biselenophene/bithiophene arrangement between PNT2Th2Se and PNT2Se2Th polymers, (2) biselenophene/bithiophene and quarterselenophene donor units between PNT2Th2Se/PNT2Se2Th and PNT4Se polymers, and (3) side-chain modification between the 2octyldodecylthiophene (OD)-and 2-decyltetradecyl (DT)-series polymers. The incorporation of selenophene units in the copolymers induces stronger charge transfer to improve the light-harvesting capability while maintaining the strong intermolecular interactions to preserve the intrinsic crystallinity for high carrier mobility. The organic field-effect transistor device using PNT2Th2Se-OD achieved a high hole mobility of 0.36 cm 2 V −1 s −1 with an on/off ratio of 1.9 × 10 5 . The solar cells with PNT2Th2Se-OD:PC 71 BM exhibited a power conversion efficiency of 9.47% with a V oc of 0.68 V, an fill factor of 67%, and an impressive J sc of 20.69 mA cm −2 .

Naphthobispyrazine Bisimide: A Strong Acceptor Unit for Conjugated Polymers Enabling Highly Coplanar Backbone, Short π–π Stacking, and High Electron Transport

“…Naphthobischalcogenadiazole (NXz) units, such as naphtho­[1,2- c :5,6- c ′]­bis­[1,2,5]­thiadiazole (NTz), − naphtho­[1,2- c :5,6- c ′]­bis­[1,2,5]­oxadiazole (NOz), , and their derivatives, − are emerging acceptor units for high-performance π-conjugated polymers (Figure a). Due to the large π-electron systems that can induce strong π–π intermolecular interaction, π-conjugated polymers based on these building units can give highly ordered packing structures and thus high charge carrier mobilities in OFETs. ,,,, Interestingly, whereas polymers based on NTz showed p-type characteristics, those based on NOz showed the ambipolar behavior due to the enhanced electron deficiency in NOz relative to that in NTz . We have recently reported a series of polymers based on dicyano NTz (CN-NTz), which also exhibits enhanced electron deficiency compared to NTz, and found that the polymers have ambipolar to n-type semiconducting characteristics depending on the co-monomer unit in the backbone .…”

Incorporation of Selenopheno[3,2-b]pyrrole into Benzothiadiazole-Based Small Molecules for Organic Field-Effect Transistors

“…Moreover, varying chalcogen heteroatoms of heteroaromatic systems in semiconductors have directly influenced optoelectronic properties and OFET performance. ,− Particularly, changing heteroatom from sulfur to selenium in the standard spacers of organic semiconductors, such as thiophene and thiophene-vinyl-thiophene, has improved the charge carrier mobility of the materials. − Furthermore, structurally diverse, selenophene consisting OFET materials have shown hole, , electron, − and ambipolar , type charge carrier transporting properties with good charge carrier mobilities (>0.1 cm 2 V –1 s –1 ). Selenophene containing donor and acceptor semiconducting materials have been used in organic solar cells to improve power conversion efficiencies and short-circuit current densities. − Selenophene containing conjugated polymers ,− were used in solar cells and OFETs.…”

Synthesis of side-chain regioregular and main-chain alternating poly(bichalcogenophene)s and an ABC-type periodic poly(terchalcogenophene)

“…Structurally similar to thiophene, two other ve-membered heterocycles in the chalcogenophene family-selenophene and tellurophene, featuring group-16 Se and Te elements, respectively-have attracted considerable interest because (1) Se and Te atoms are larger and have d-orbitals of higher polarizability (relative to S) to induce strong Se/Se and Te/Te attractions, potentially strengthening their interpolymer interactions, [37][38][39][40][41] and (2) as the chalcogen becomes heavier, the p-electrons in selenophene and tellurophene tend to adopt a more quinoidal character with higher coplanarity, giving rise to narrower band gaps and bathochromic shis in their absorption. [42][43][44][45][46][47][48][49][50] The homopolymers 3alkylselenophene (P3AS) 51,52 and 3-alkyltellurophene (P3ATe) 53,54 have also been prepared using the KCTP. We were interested in studying the effects of incorporating two different chalcogenophenes into a single polymer to generate a new class of poly(bichalcogenophene)s. By integrating thiophene, selenophene, and tellurophene units in a single polymer in a controlled sequence, the properties of the polymer could presumably be tailored specically.…”