Doping mechanisms of N-DMBI-H for organic thermoelectrics: hydrogen removal vs. hydride transfer

Abstract

The doping mechanisms of N-DMBI-H in n-type organic semiconductors were revealed at the first-principles level.

Sequential Doping of Ladder-Type Conjugated Polymers for Thermally Stable n-Type Organic Conductors

“…After spin-coating, the films were dipped into deionized water to remove residual MSA and then thermally annealed at 110 °C for 1 h. Very low conductivity values (<1 × 10 –3 S cm –1 ) were observed for all of the coprocessing doped BBL films, regardless of the N-DMBI-to-BBL monomer unit molar ratio (3–100%). Because N-DMBI is a weak base and the n-doping process progresses via either hydrogen removal or a thermally activated hydride transfer process, 45 we ascribe the low conductivity of the coprocessed films to inefficient doping with N-DMBI in the strongly acidic MSA solution.…”

n-Type organic semiconducting polymers: stability limitations, design considerations and applications

“…N-DMBI is one of the most commonly used and best understood n-type dopants for OTE materials, likely due to the ambient stability of the native species. 66,172,173 Stability of N-DMBI and TAM as n-type dopant precursors originate from the mechanism of doping, which is via a latent hydride (formed in situ) or an initial hydrogen removal, rather than simply donating an electron, meaning requirements of the n-type dopant to have a low IP are alleviated. 154,170,172 When using N-DMBI, the resulting cation has exhibited poor miscibility with typical alkyl substituted n-type OSCs, one rationale for investigating more polar sidechains.…”

Revisiting doping mechanisms of n-type organic materials with N-DMBI for thermoelectric applications: Photo-activation, thermal activation, and air stability

“…In contrast, recent density functional theory (DFT)-supported mechanistic studies suggest that pathway II is the dominant mechanism when thermal annealing is performed on solid-state films. 21,22 Pathway II is characterized by an homolysis bond cleavage of the weak C-H bond, forming the neutral N-DMBI • radical with a singly occupied molecular orbital (SOMO) level DFT-calculated at ca. -2.4 eV 19,23 .…”