Synthesis and photovoltaic properties of copolymers with a fluoro quinoxaline unit

Abstract

Two novel accepter units, namely, difluoroquinoxaline and monofluoroquinoxaline, were prepared and used for the synthesis of the conjugated polymers containing electron donor-acceptor pairs for use in organic photovoltaics. The introduction of a fluorine atom into the quinoxaline moiety resulted in polymers with lowered highest occupied molecular orbital (HOMO) energy levels; this increased the open circuit voltage of the devices based on the synthesized polymers. The conjugated polymers containing difluoroquinoxaline and monofluoroquinoxaline, namely, thiophene and benzodithiophene, were synthesized using the Stille polymerization reaction to produce PEHBQxF2, PEHBQxF1, PEHBDTQxF2, and PEHBDTQxF1. The HOMO energy levels of PEHBQxF2, PEHBQxF1, PEHBDTQxF2, and PEHBDTQxF1 were determined to be 25. 66, 25.52, 25.54, and 25.39 eV, respectively. The device with PEHBDTQxF2/PC 71 BM (1:2, w/w) and containing diiodooctane (3 vol %) exhibited the best photovoltaic performance, with its V OC being 0.79 V, J SC being 10.44 mA/cm 2 , FF being 68%, and PCE being 5.58%. V C 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 821-830

Synthesis and properties of mono‐ and di‐fluoro‐substituted 2,3‐didodecylquinoxaline‐based polymers for polymer solar cells

“…Key intermediates (4‐hexylthiophen‐2‐yl)trimethylstannane, 1 , and 2 were synthesized according to the literature. The Stille coupling reaction of (4‐hexylthiophen‐2‐yl)trimethylstannane with each of 1 and 2 afforded compound 3 and 4 , respectively.…”

“…Monomers 2,5‐bis(trimethylstannyl)thiophene ( M3 ) were purchased from Aldrich chemicals. Whereas, compound (4‐hexylthiophen‐2‐yl)trimethylstannane, 1 and 2 were synthesized using the reported procedures. The detailed synthetic procedure to monomers M1 and M2 , and polymers P(Tt‐FQx) and P(Tt‐DFQx) are summarized below.…”

“…We have been interested to prepare alkyl‐substituted Qx‐based polymers for PSCs . The insertion of alkyl instead of aryl groups on 2nd and 3rd‐positions (Fig.…”

“…) of the Qx expected to show slightly different electron withdrawing ability and mainly increase the solubility of resulting polymers. In this instance, we prepared 6‐fluoro‐2,3‐didodecylquinoxaline (FQx) and 6,7‐difluoro‐2,3‐didodecylquinoxaline (DFQx) derivatives and polymerized with electron‐rich BDT derivative . The resulting polymers PEHBDTQxF1 and PEHBDTQxF2 exhibited comparable photovoltaic performances with that of PDBTQEH .…”

Hybrid Photocatalyst for Hydrogen Production: The Effect of Fluorine on Optoelectronic Properties of Conjugated Porous Polymers

“…So, bare PQ shows two absorption bands at around 460 and 650 nm in acetonitrile or benzene, which correspond with the triplet-triplet (T-T) absorption spectra with different lifetime depending of the solvent (i.e., 6.7 and 450 ns in acetonitrile or benzene, respectively). [33,34] Furthermore, it is known that the photophysical for PQ derivatives is heavily depending on the solvent, environment, and measurement conditions. [71] On the other hand, a remarkable enhancement of the lifetimes was observed for the hybrids compared to the bare TiO 2 monitoring at 460 nm, confirming a slow-down of the electron-hole pair recombination process (Figure 5d).…”