Effect of thiophene spacers in benzodithiophene‐based polymers for organic electronics

Abstract

Poly{2,6‐bis(thiophene‐2‐yl)‐4,8‐bis(5‐dodecylthiophen‐2‐yl)benzo[1,2‐b:4,5‐b']dithiophene} [poly(Th‐bDTBDT‐Th)] was successfully synthesized through Stille coupling polymerization. The addition of the thiophene spacer groups between the benzodithiophene units resulted in improved performance in optoelectronic devices. This was attributed to the reduced lamellae stacking distance in thin film with prominent π–π stacking peak indicating close assembly of poly(Th‐bDTBDT‐Th). Spacing between the benzodithiophene units in poly(Th‐bDTBDT‐Th) helped the close packing of dodecyl chains and generated improved π stacking interaction. For poly(Th‐bDTBDT‐Th), the measured average field effect mobility was 2.32 × 10−3 cm2 V−1 s−1 and average hole mobility in vertical direction was 2.92 × 10−5 cm2 V−1 s−1. Charge transport in both directions was improved by one order of magnitude with the presence of the thiophene spacer. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 3942–3948

A Wide Bandgap Polymer Donor Composed of Benzodithiophene and Oxime-Substituted Thiophene for High-Performance Organic Solar Cells

“…Compared with the solution spectrum, these two peaks in the thin-film spectrum red-shifted by 18 and 15 nm, respectively, indicating the planarization and more extended conjugation of the polymer backbone in the solid state. 51,52 The optical bandgap calculated from the absorption onset of the polymer film is 2.03 eV, which is very similar to that (E g = 2.06 eV) 49 (see also Figure S9) of the analogous polymer PBDT-Th without the oxime side chains on the thiophene units, indicating the minimal effect of the oxime side chains on the bandgap of PBDTTO. The wide bandgap and strong absorption in the range from 400 to 610 nm of this polymer are desirable for forming complementary absorption with narrow bandgap nonfullerene acceptors (NFAs), especially Y6 that has an E g of 1.33 eV and an absorption range of 600−930 nm.…”

“…As shown in Figure a, in solution, PBDTTO showed a low-energy peak with a wavelength of 509 nm at the maximum absorption (λ max ) and a high energy peak at 350 nm, which originate from the π–π* transition of the extended conjugation of the donor backbone and the absorption by the conjugated thienyl side chains on the BDT units, respectively. ,, The existence of the vibronic absorption shoulder at 538 nm implies the occurrence of preaggregation of this polymer in solution. , In the thin film, the maximum absorption peak and the shoulder peak are located at 527 and 553 nm, respectively. Compared with the solution spectrum, these two peaks in the thin-film spectrum red-shifted by 18 and 15 nm, respectively, indicating the planarization and more extended conjugation of the polymer backbone in the solid state. , The optical bandgap calculated from the absorption onset of the polymer film is 2.03 eV, which is very similar to that ( E g = 2.06 eV) (see also Figure S9) of the analogous polymer PBDT-Th without the oxime side chains on the thiophene units, indicating the minimal effect of the oxime side chains on the bandgap of PBDTTO. The wide bandgap and strong absorption in the range from 400 to 610 nm of this polymer are desirable for forming complementary absorption with narrow bandgap nonfullerene acceptors (NFAs), especially Y6 that has an E g of 1.33 eV and an absorption range of 600–930 nm …”

“…As shown in Figure 2a, in solution, PBDTTO showed a low-energy peak with a wavelength of 509 nm at the maximum absorption (λ max ) and a high energy peak at 350 nm, which originate from the π−π* transition of the extended conjugation of the donor backbone and the absorption by the conjugated thienyl side chains on the BDT units, respectively. 49,51,52 The existence of the vibronic absorption shoulder at 538 nm implies the occurrence of preaggregation of this polymer in solution. 53,54 In the thin film, the maximum absorption peak and the shoulder peak are located at 527 and 553 nm, respectively.…”

Improved Self-Assembly of P3HT with Pyrene-Functionalized Methacrylates

“…Low manufacturing cost and the ability to make large area, flexible, and lightweight devices make organic semiconductors valuable materials. Studies based on different approaches have been reported on organic photovoltaics (OPVs), − organic field-effect transistors (OFETs), − organic light-emitting diodes (OLEDs), − organic lasers, , and memory devices. , For the fabrication of efficient organic electronic devices, tuning of the mechanical properties and charge transport of organic semiconductors has to be addressed through the development of structure–property relationships. , Organic semiconductors are highly versatile materials that can be functionalized to tune function, morphology, and optical properties. To that end, regioregular poly­(3-hexylthiophene) ( rr -P3HT) is among the extensively studied semiconducting polymers that have been tested as the active component in organic electronic applications. , …”

“…12,13 For the fabrication of efficient organic electronic devices, tuning of the mechanical properties and charge transport of organic semiconductors has to be addressed through the development of structure−property relationships. 14,15 Organic semiconductors are highly versatile materials that can be functionalized to tune function, morphology, and optical properties. To that end, regioregular poly(3-hexylthiophene) (rr-P3HT) is among the extensively studied semiconducting polymers that have been tested as the active component in organic electronic applications.…”