Peripherally Fluorinated Silicon Phthalocyanines: How Many Fluorine Groups Are Necessary for Air-Stable Electron Transport in Organic Thin-Film Transistors?

• DOI: 10.1021/acs.chemmater.3c01342
• Publication Date: 2023-09-28T18:24:32Z
• Authors: Benjamin King; Mário C. Vebber; Raluchukwu Ewenike; Marine Dupuy; Callum French; Jaclyn L. Brusso; Benoît H. Lessard
• Keywords: HOMO/LUMO; Fluorine; Organic semiconductor; Electron Mobility; Organic Electronics; Ultraviolet photoelectron spectroscopy

Silicon phthalocyanines (R2–SiPcs) are an emerging class of high-performance n-type semiconductors used in organic electronics, which historically have suffered from operational instability air. We report the synthesis R2–SiPcs with varying degrees peripheral fluorination, R2–FxSiPcs (x = 0, 4, or 16), and different axial phenoxy groups leading to 12 derivatives 0 26 fluorine atoms molecular structure going non-operational devices ambient conditions fully air-stable operation thin-film transistors (OTFTs). Ultraviolet photoelectron spectroscopy revealed that fluorination caused a decrease up 0.9 eV energy level lowest unoccupied orbital (LUMO). This reduction LUMO coincides threshold voltage (VT) resulting OTFT. All compounds containing 16 one four OTFTs yielded electron transport at humidity 40%. Power spectral density functions (PSDF) atomic force microscopy imaging also demonstrated for similar morphologies across series same group, larger domain size smaller grain boundaries film led higher overall mobility (μe).