End-cap Group Engineering of a Small Molecule Non-Fullerene Acceptor: The Influence of Benzothiophene Dioxide

Abstract

In this study, a sulfonyl-containing end-capping moiety, benzothiophene dioxide, was selected to prepare the nonfullerene acceptor ITBC. ITBC has an acceptor−donor− acceptor (A-D-A) structure, with indacenodithieno[3,2-b]thiophene (IDTT) as the electron-rich core moiety. The strong electron-withdrawing sulfonyl acceptor units leads to extended UV−vis absorption into the near-IR region and relatively low frontier molecular orbital energy levels (LUMO/HOMO: −4.13 eV/−5.61 eV) with a narrow bandgap of 1.48 eV. These values compare favorably to the well-studied small molecule acceptor 2-(3-oxo-2,3-dihydroinden-1-ylidene)malononitrile end-capped indacenodithieno[3,2-b]thiophene (ITIC). A power conversion efficiency of 4.17% was achieved by fabricating organic solar cells with the fluorinated conjugated polymer FTAZ as the donor and ITBC as the acceptor. These results indicate that benzothiophene dioxide is a novel electron-withdrawing end-capping unit for ITBC, and can be used as an electron acceptor for organic solar cells.

Highly Conjugated, Fused-Ring, Quadrupolar Organic Chromophores with Large Two-Photon Absorption Cross-Sections in the Near-Infrared

“…Normalized 1PA spectra in dilute chloroform solutions (ca. 1–10 μM) for seven-ring, indacene-based compounds ITIC , ITIC3 , F7IC , and ITBC are plotted in Figure . The reported reduction potentials for films of these compounds shift to increasingly reducing (more negative) potential in the order ITIC < ITIC3 < F7IC < ITBC , suggesting that the acceptor strength of the end groups increases in the same order. Previous studies of quadrupolar A-D-A chromophores , show bathochromic shifts of the 1PA band with increasing acceptor strength; the successively bathochromically shifted 1PA and concomitantly increased M ge values in the present series, as summarized in Table , is consistent with this behavior and with the acceptor strength implied by the reduction potentials.…”

“…The compounds were synthesized according to the literature: F5-9IC , IUIC , F6-10IC , ITIC , ITIC3 , and ITBC …”

“…The compounds were synthesized according to the literature: F5-9IC, 32 IUIC, 38 F6-10IC, 33 ITIC, 31 ITIC3, 34 and ITBC. 39 Steady-State Absorption Spectroscopy. UV−vis-NIR measurements were performed on a Shimadzu UV3101-PC dual arm spectrometer using 1 cm quartz cuvettes.…”

Push–pull thiophene-based small molecules with donor and acceptor units of varying strength for photovoltaic application: beyond P3HT and PCBM

“…[14][15][16] The different nature of the D and A fragments allows modulating the shift of electron density from the D to the A moiety achieving a fine control of the optoelectronic properties such as a wider absorption range of the solar emission spectrum. [17][18][19][20][21][22] Furthermore, well-engineered molecular moieties may help in guiding the morphology of the active layer thus eliciting suitable phase separation, one of the most demanding tasks to achieve high efficiency in BHJ. 23 Over the years, different push-pull small molecules, characterized by a wide diversity in the alternation of the D and A functional units, such as D-A, D-A-A 0 , A-D-A, D-A-D sequence, have been synthesized to be employed as donors counterpart in blend with fullerene-based acceptors.…”

Pyrrolo[3,2-b]pyrrole-1,4-dione (IsoDPP) End Capped with Napthalimide or Phthalimide: Novel Small Molecular Acceptors for Organic Solar Cells

“…There are several ways to tune the properties of non-polymeric NFAs in order to boost the device performance. For example, a desired NFA core chromophore can have its properties engineered by variation of the end-capping units to achieve the desired large absorption coefficient, electron affinity, ionization potential, and electron mobility [ 6 , 10 , 11 , 12 ].…”